(PDF) Evidence of lower atmospheric influences/coupling in midlatitude long-term mesopause-region temperatures

An unique midlatitude noctunal mesopause-region temperatures resulting from 25 years of Na lidar observations at Colorado State University and Utah State University reveals influences of tropospheric and/or stratospheric forcing. These includes signals of Mt. Pinatubo eruption and El Nino Southern Oscillation, as well as altitude-dependent (wave-like structures) responses to the 11-year and 27-day solar flux variability. Though the cause for these intriguing signals is not yet known, publications in 2015 by colleagues elsewhere have also shown similar effects in temperatures from satellite data.

PEM03-01 Japan Geoscience Union Meeting 2016 Evidence of lower atmospheric influences/coupling in midlatitude long-term mesopause-region temperatures *Chiao Yao She1,2 1.Emeritus, Colorado State University, USA, 2.Visiting, National Institute of Polar Research, Japan An unique midlatitude noctunal mesopause-region temperatures resulting from 25 years of Na lidar observations at Colorado State University and Utah State University reveals influences of tropospheric and/or stratospheric forcing. These includes signals of Mt. Pinatubo eruption and El Nino Southern Oscillation, as well as altitude-dependent (wave-like structures) responses to the 11-year and 27-day solar flux variability. Though the cause for these intriguing signals is not yet known, publications in 2015 by colleagues elsewhere have also shown similar effects in temperatures from satellite data. Keywords: Mesopause temperatures, Lower atmospheric influences, 25 years Na lidar observation ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-01 - PEM03-02 Japan Geoscience Union Meeting 2016 Strong long-term cooling of the ionosphere observed by multiple incoherent scatter radars *Shunrong Zhang1, John Holt1, Phil Erickson1, Mary McCready2, Michael Nicolls2 1.MIT Haystack Observatory, 2.SRI International Compelling evidence for long-term changes in the upper atmosphere over the last several solar cycles has emergedfollowing a seminal modeling study by Roble and Dickson (1989), suggesting potential effects of increasedgreenhouse gases on the ionosphere and thermosphere. Direct measurements of the cooling trend come from in situ neutral density data available since 1960s, and from ground-based incoherent scatter radar (ISR) plasma temperature data available systematically at Millstone Hill (42.6N 288.5) since the late 1960s and elsewhere since the later years. Other observations also seem to show indirectly signs of the cooling which are not alwaysconsistent. However, the cool intensity from ISR data appear much more significant than expected from effects ofanthropogenic increases in the CO2 mixing ratio, as initially suggested by Millstone Hill data. We have now examined furth the strong cooling with additional new datasets of ISRs: the Sondrestrom (67.0N, 309.1E) ISR(1990-), which is typically located at cusp during the day, as well as Chatanika/Poker Flat (65.1N, 212.6E) ISRs(1976-) which is often considered as an aurora latitude site. New analyses of these observations continue toindicate strong ionospheric cooling, therefore imposing an important question as to what is really driving theselong-term changes in the upper atmosphere. We will make comparisons of these ISR results from mid- and highlatitudes, and discuss potential drivers for the unexpected strong cooling in the ionosphere. Keywords: long-term change, ionosphere, incoherent scatter radar ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-02 - PEM03-03 Japan Geoscience Union Meeting 2016 Behaviour of the semi-diurnal tidal modes in the MLT using the SuperDARN meteor-radar chain *Patrick Espy1,2, Nora Stray1,2, Kåre Backer-Owe1, Magnus Waalekalv1, Robert Hibbins1,2 1.Department of Physics, Norwegian University of Science and Technology, 2.Birkeland Centre for Space Science, Bergen, Norway, Atmospheric tides in the mesosphere and lower thermosphere (MLT) have been shown to couple to the ionosphere, and may themselves be enhanced by the Joule heating associated with energetic particle precipitation. However, studies have shown that the efficiency of this coupling to and from the ionosphere depends on the spatial mode of the tides. While individual stations can provide accurate information on the temporal evolution of the tides, they do not allow the different spatial modes to be separated. Similarly, satellite observations can determine the spatial modes, but alias temporal changes in tidal amplitude and structure. A method has been developed to observe the spatial structure of atmospheric tides in the northern hemisphere (50o-66o N) MLT using neutral atmosphere winds derived from meteor trail drifts observed by a longitudinal chain of Super Dual Auroral Radar Network (SuperDARN) radars. The tidal amplitudes determined at each radar station in the chain can be combined to infer the zonal wavenumber 1 and 2 structure of the tide and its temporal evolution without the spatial-temporal aliasing present in satellite observations. Details of the method applied to the meteor radar data will be presented, and the amplitudes and temporal variations of the wavenumber 1 and 2 components of the semi-diurnal tide in the MLT will be examined during stratospheric warming and particle precipitation events. Keywords: Dynamics, Tides, coupling ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-03 - PEM03-04 Japan Geoscience Union Meeting 2016 Coupling process among the mesosphere, thermosphere and ionosphere elucidated by the ISS-IMAP mission *Akinori Saito1, Atsushi Yamazaki2, Takeshi Sakanoi3, Ichiro Yoshikawa4, Yuichi Otsuka5, Yuta Hozumi1 1.Department of Geophysics, Graduate School of Science, Kyoto University, 2.Institute of Space and Astronautical Science / Japan Aerospace Exploration Agency, 3.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, 4.The University of Tokyo, 5.Nagoya University ISS-IMAP (Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping) mission was installed on the Exposed Facility of Japanese Experiment Module of the International Space Station, EF of ISS-JEM, and consisted of two sets of imagers to observe the structures in the Mesosphere, Thermosphere and Ionosphere (MTI) region. Visible-light and infrared spectrum imager (VISI) of ISS-IMAP observed the airglow of 730nm (OH, Alt. 85km), 762nm (O2, Alt. 95km), and 630nm (O, Alt. 250km) in the MTI region, and Extra ultraviolet imager (EUVI) observed the resonant scattering of 30.4nm (He+) and 83.4nm (O+) from ion in the Ionosphere and Plasmasphere. ISS-IMAP was operated from 2012 to 2015. VISI elucidated global distributions of the airglow structures whose scale size is 50-500km in he nightside. The wavy structures that are interpreted to be generated by atmospheric wave were frequently observed. Some of them showed clear relationship with tropospheric phenomena as its source. EUVI elucidated global distributions of He ion. Its seasonal distribution indicates the thermospheric wind dominates the ion distribution of the topside ionosphere and the plasmasphere. Coupling processes among the MTI region and the lower atmosphere will be discussed in the presentation. Keywords: Ionosphere, Thermosphere, airglow ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-04 - PEM03-05 Japan Geoscience Union Meeting 2016 3-years Occurrence Variability of Concentric Gravity Waves in the Mesopause Observed by IMAP/VISI *Septi Perwitasari1, Takeshi Sakanoi1, Takuji Nakamura2, Mitsumu K. Ejiri2, Masaki Tsutsumi2, Yoshihiro Tomikawa2, Yuichi Otsuka3, Atsushi Yamazaki4, Akinori Saito5 1.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, 2.National Institute of Polar Research, 3.Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan, 4.JAXA/ISAS, 5.Geophysics Department, Kyoto University, Kyoto, Japan We report the first statistical study on concentric gravity waves (CGWs) in the mesopause by using 3 years data obtained by IMAP/VISI. 235 CGWs events were found with horizontal wavelength ranging from 40 to 250 km and maximum radius of 200 to 3000 km. Occurrence of the CGWs was significantly higher during non-solstice months (February-May and August–November) than solstice months (June-July and December-January), suggesting low to moderate wind are preferable for CGWs upward propagation. The latitudinal distribution of the CGWs centers had peaks in mid latitude (40°N and 40°S) and minimum at low latitude (10°S). More events were found in the summer hemisphere mid-latitudes, with a clear transition between north and south hemisphere around equinoxes. The information of the preferable regions seen in the global distribution map and the seasonal distribution could be useful for region and seasonal selection of CGWs’ future studies. Keywords: Concentric gravity wave, O2 nightglow emission, Mesopause ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-05 - PEM03-06 Japan Geoscience Union Meeting 2016 A numerical study of the effects of migrating tides on thermosphere midnight density maximum *Jiuhou Lei1, Haibing Ruan1, Jian Du2, Wenbin Wang3 1.USTC University of Science and Technology of China, 2.Department of Physics and Astronomy, University of Louisville, USA, 3.High Altitude Observatory, National Center for Atmospheric Research, USA We employed the NCAR Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) and the extended Canadian Middle Atmosphere Model (eCMAM) to investigate the role of the migrating terdiurnal tide on the formation and variation of the thermosphere midnight temperature maximum (MTM) and midnight mass density maximum (MDM). The migrating terdiurnal tide from the eCMAM was applied at the TIEGCM’s lower boundary, along with the migrating diurnal and semidiurnal tides from the Global Scale Wave Model (GSWM). Several numerical experiments with different combinations of tidal forcing at the TIEGCM’s lower boundary were carried out to determine the contribution of each tide to MTM/MDM. We found that the interplay between diurnal, semidiurnal and terdiurnal tides determines the formation of MTM/MDM and their structure in the upper thermosphere. The decrease of thermospheric mass density after MDM reaches its maximum at ~02:00 local time is mainly controlled by the terdiurnal tide. Furthermore, we examined the generation mechanisms of the migrating terdiurnal tide in the upper thermosphere and found that they come from three sources: upward propagation from the lower thermosphere, in-situ generation via nonlinear interaction and thermal excitation. Keywords: thermosphere, midnight density maximum, migrating tides ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-06 - PEM03-07 Japan Geoscience Union Meeting 2016 Ionospheric Effects of Strong El Niño Southern Oscillation Conditions *Thomas J Immel1, Guiping Liu1, Jeffrey Forbes2, Astrid Maute4, Vu Nguyen2, Ruth Lieberman3, Katelynn Greer1 1.University of California, Berkeley, 2.University of Colorado, 3.GATS Inc., 4.High Altitude Observatory The occurrence of a very strong positive phase in the El Nino Southern Oscillation (ENSO) in late 2015 has had effects on weather around the entire planet. Furthermore, recent investigations show that ENSO-related changes in tropospheric water vapor and rainfall drive significant changes in the temperature and wind structure in the middle atmosphere, through the modification of the spectrum of atmospheric tides. Given that several components of the tidal spectrum can propagate into the thermosphere, ENSO-related changes at altitudes above the mesopause and into the ionosphere may be expected. Based upon historical events in 1997 and 1998, we will show the ionospheric and thermospheric variations one may expect for El Ni\~no and La Ni\~na conditions. We will also show middle atmosphere conditions measured by the NASA TIMED SABER instrument for the 2015-2016 event. These efforts are enabled in part by modeling capabilities developed for the upcoming NASA Ionospheric Connection Explorer mission. Keywords: El Niño, Atmospheric physics, ionosphere, thermosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-07 - PEM03-08 Japan Geoscience Union Meeting 2016 Impact of tidal variability on the mean state of the ionosphere and thermosphere during sudden stratosphere warmings *Nicholas M Pedatella1, Astrid Maute2, Hanli Liu2, Arth Richmond2 1.COSMIC Program Office, University Corporation for Atmospheric Research, 2.High Altitude Observatory, National Center for Atmospheric Research Observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites reveal a global reduction in the zonal and diurnal mean F-region peak electron density (NmF2) during sudden stratosphere warmings (SSWs). In the present study we investigate the source of the global NmF2 decrease using Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) and Thermosphere-Ionosphere-Electrodynamics Global Circulation Model (TIE-GCM) simulations. The TIME-GCM simulations demonstrate that the reduction in the mean NmF2 coincides with an [O]/[N2] decrease, indicating that changes in thermosphere composition during SSWs drive the decrease in NmF2. To understand the source of the [O]/[N2] variability, we perform numerical experiments in the TIE-GCM using different forcing conditions at the model lower boundary (~97 km). The numerical experiments illustrate that variability in the migrating semidiurnal solar tide (SW2) during SSWs drives the changes in thermosphere composition. In particular, the enhancement of the SW2 during SSWs appears to alter the mean circulation in the MLT, leading to a reduction in atomic oxygen throughout the thermosphere. The results demonstrate that, in addition to modulating the low latitude electrodynamics, tidal variability during SSWs significantly impacts the mean state of the ionosphere and thermosphere. Keywords: sudden stratosphere warming, ionosphere variability, thermosphere composition ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-08 - PEM03-09 Japan Geoscience Union Meeting 2016 Global Responses of Gravity Waves to Planetary Wave Variations during SSWs Observed by SABER *Chihoko Cullens1, Scott England1, Thomas Immel1 1.University of California Berkeley This study describes the global responses of observed gravity waves (GWs) to winter planetary wave (PW) variations during stratospheric sudden warmings (SSWs) using TIMED-SABER temperature measurements. Previous studies have shown responses of atmospheric temperature and parameterized GW drag to SSWs; however, the responses of actual global GW observations to SSWs have not been presented before. The responses are shown by calculating correlations between vertical components of Eliassen-Palm (EP) fluxes in the winter polar stratosphere and global GW temperature amplitudes derived from SABER observations. Consistent with previous ground-based and satellite observations, winter EP fluxes show positive correlations with GWs in the winter hemisphere. More interestingly, winter stratospheric EP fluxes are positively correlated with GWs in the tropics and in the summer mesosphere, indicating global variations of GWs in response to PW variations in the winter hemisphere. To study the mechanism of GW response to SSWs, global wind simulations from SD-WACCM are used. Zonal wind anomalies (differences in the wind before and during SSWs) extend from the winter stratosphere to the summer mesosphere. By comparing anomalies in background winds to the observed patterns in the correlations between GWs and winter EP fluxes, we find that regions of positive correlation follow changes in background winds and zero-wind lines. The results indicate that responses of SABER GWs in the summer hemisphere to winter PW variations during SSWs are likely caused by changes in GW propagation due to the changes in winds and atmospheric circulation. These observed changes in global GWs during SSWs can affect the ionosphere and thermosphere, and studying global GW variation during SSWs is important for understanding mechanisms of vertical coupling. Keywords: Inter-hemispheric Coupling, Gravity Wave, Stratospheric Sudden Warming ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-09 - PEM03-10 Japan Geoscience Union Meeting 2016 Tidal variabilities and their effects on the upper atmosphere during stratospheric sudden warmings studied with a long-term whole atmosphere-ionosphere simulation *Hidekatsu Jin1, Yasunobu Miyoshi2, Hitoshi Fujiwara3, Hiroyuki Shinagawa1 1.National Institude of Information and Communications Technology, 2.Kyushu University, 3.Seikei University Recent studies have revealed that large-scale phenomena in the lower atmosphere have significant impacts on the upper atmosphere. For example, during the period of a prominent stratospheric sudden warming (SSW) in January 2009, the low latitude ionosphere was observed to perturb significantly. In previous study, we have simulated the event using a whole atmosphere-ionosphere coupled model called GAIA which implemented the meteorological reanalysis data in order to examine the effects of realistic lower atmospheric forcing. The model can reproduce overall main features in the middle and upper atmospheric variations during the SSW event, and the analysis suggests that the upward propagating planetary wave in the polar region can change not only global zonal wind distribution but also propagation of atmospheric tides, which leads to the perturbation of low latitude ionosphere [Jin et al., JGR, 2012]. In this study, we have carried out a longer run from 1996 to 2014, and analyzed statistically the effects of stratospheric sudden warmings on the upper atmosphere. We especially discuss the role of migrating tides in detail. Keywords: stratospheric sudden warming, atmospheric tide, ionosphere, thermosphere, simulation, modeling ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-10 - PEM03-11 Japan Geoscience Union Meeting 2016 Quasi Two Day Wave Response in the Ionosphere Using TIME-GCM Nudged with NOGAPS-ALPHA *Jack C. Wang1, Loren C. Chang1, Yue Jia2, Wenbin Wang3, David E. Siskind4 1.Graduate Institute of Space Science, National Central University, Taoyuan, Taiwan, 2.Department of Atmospheric and Planetary Sciences, Hampton University, Hampton, VA, USA, 3.High Altitude Observatory, National Center for Atmospheric Research, Boulder, Colorado, USA, 4.Space Science Division, Naval Research Laboratory, Washington, District of Columbia, USA The quasi two day wave (QTDW) is a planetary wave that can be enhanced rapidly to extremely large amplitudes in the mesosphere and lower thermosphere (MLT) region during the northern winter post-solstice period. The dissipation of the planetary wave can change the background dynamics and the composition of MLT. This feature can also drive robust variability of the ionosphere system, for example, the total electron content (TEC). In this study, we present five January case studies of QTDW events (2005, 2006, 2008, 2009, 2010) by using the Thermosphere-Ionosphere-Mesosphere Electrodynamics-General Circulation Model(TIME-GCM) nudged with the Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS-ALPHA) Weather Forecast Model. With NOGAPS-ALPHA introducing a more realistic lower atmospheric forcing in TIME-GCM, we can investigate ionosphere system coupling with the MLT region when dramatic features associated with the QTDW occur in middle atmosphere. This work opens a new method to evaluate the physical mechanism of ionospheric coupling from below during QTDW events. Keywords: Data Assimilation, Quasi Two Day Wave, TIME-GCM, NOGAPS-ALPHA, Ionosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-11 - PEM03-12 Japan Geoscience Union Meeting 2016 Mesospheric, thermospheric, and ionospheric responses to acoustic and gravity waves at large amplitudes and small scales *Jonathan B Snively1, Matthew D. Zettergren1 1.Embry-Riddle Aeronautical University Acoustic and gravity waves (AGWs) are routinely observed in the Earth's mesosphere, lower thermosphere, and ionosphere (MLTI) from ground and space based platforms via remote sensing of mesospheric airglow intensity and ionospheric total electron content (TEC). Recent data from imagers and GPS receivers provide key insight into wave disturbances to the MLTI at high resolution above their respective sources, which include natural hazard events, orographic forcing, and tropospheric convection [e.g., Galvan et al., RS, 47(4), 2012; Nishioka et al., GRL, 40(21), 2013; Fritts et al., BAMS, 2015; Miller et al., PNAS, 112(49), 2015]. Gravity waves with short periods (~minutes) and small scales (~tens to hundreds of kilometers) may carry sufficient momentum to have very strong and localized effects on the state of the MLTI [Fritts et al., JGR, 119(24), 2014]. Evidence also suggests nonlinear impacts of acoustic waves (with periods ~minutes) in the ionosphere and thermosphere, for example as indicated by measured TEC depletions following the Tohoku 2011 earthquake [e.g., Kakinami et al., GRL, 39(13), 2012]; simulations by Zettergren and Snively [AGU FM, NH32C-02, 2015] also support this interpretation. We investigate the observable features of acoustic and gravity waves at large amplitudes that can strongly perturb multiple layers of the MLTI system. New high-resolution, nonlinear, compressible, atmospheric dynamics models are used to drive airglow photochemical and ionospheric models [e.g., Snively, GRL, 40(20), 2013; Zettergren and Snively, JGR, 120(9), 2015]. Results elucidate the underlying dynamics of nonlinear short-period wave disturbances, in addition to the responses of both the mesospheric airglow and thermosphere-ionosphere systems to enable direct comparisons with data (airglow imagery and TEC). Modeling also reveals that apparently coherent AGWs, at large amplitudes consistent with observations, may have strong localized impacts that may (or may not) be readily observable. Observations and modeling of dynamics spanning multiple layers in the MLTI system may provide new insight into wave coupling processes, the evolutions of broad wave spectra, and wave effects over short time scales. Keywords: Acoustic and Gravity Waves, Airglow, Ionosphere, Mesosphere and Lower Thermosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-12 - PEM03-13 Japan Geoscience Union Meeting 2016 Relationship between ionospheric and atmospheric perturbations associated with typhoons Shinichiro Hirabayashi1, *Hiroyuki Nakata1, Toshiaki Takano1, Ichiro Tomizawa2, Hiromichi Nagao3 1.Graduate School of Engineering, Chiba University, 2.Center for Space Science and Radio Engineering, The University of Electro-Communications, 3.Earthquake Research Institute,The University of Tokyo It is known that ionospheric disturbances are caused by extreme weather conditions, such as tornadoes and typhoons. In this study, we have examined the relationship between ionospheric and atmospheric disturbances caused by typhoons, using HF doppler (HFD) and a microbarometer. HFD observation system used in this study is maintained by The University of Electro-Communications (UEC). The receiver is located at Sugadaira, Nagano Prefecture and the transmitters are located at Chofu Campus of UEC and Nagara, Chiba Prefecture. The microbarometer is also located at Sugadaira, Nagano Prefecture. In examining typhoons which came closer to Japan since 2004, we have found ionospheric perturbations associated with 8 typhoons. In almost events, the amplitude of the doppler shift is about several hertz, which is much less than the cases for earthquakes. By dynamic spectral analyses, it is found that spectral intensity of both of ionospheric and atmospheric perturbations at frequency from 5 mHz to 50 mHz were enhanced. These results imply that the effect of the typhoon to the ionosphere is quite smaller and that the atmospheric waves propagated to the ionosphere drive the ionospheric perturbations. In this study, as a typical example, the perturbations asssociated with Typhoon WIPHA (No.18 in 2013) at 30 mHz are examined in detail. This is because the wind direction in the transmitter (Chofu), the receiver (Sugadaira), and the middle point (Chofu) is quite stable (eastward) when Typhoon WIPHA was closest to Japan for several tens of hours. The temporal variation of the spectral intensity of ionospheric perturbation is almost the same as the wind speed at Sugadaira, where is the windward of Chofu. This result shows that the ionospheric perturbations associated with typhoons is affected by the atmospheric perturbations windwardly below the ionosphere. Keywords: Ionospheric perturbation, Atmospheric perturbation, Typhoon, HF Doppler, Microbarometer ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-13 - PEM03-14 Japan Geoscience Union Meeting 2016 Behavior of Gravity waves in the thermosphere simulated by high resolution GAIA *Yasunobu Miyoshi1, Hidekatsu Jin2, Hitoshi Fujiwara3, Hiroyuki Shinagawa2 1.Kyushu University, 2.NICT, 3.Seikei University It has been recognized that gravity waves play an important role on the momentum and energy balance in the thermosphere. The effects of upward propagating gravity waves on the general circulation of the thermosphere are studied using a whole atmosphere-ionosphere coupled model (GAIA). The GAIA contains the region from the ground surface to the upper thermosphere (about 500km altitude), so that we can simulate excitation of gravity waves in the lower atmosphere and their upward propagation to the thermosphere. The high horizontal resolution of the neutral atmospheric part of GAIA is about 0.5 degree longitude by 0.5 degree latitude, and this model can simulate wide ranges of gravity waves in their thermosphere. In this study, we focus our attention on gravity wave activity in the winter thermosphere. Our simulation result indicates that some of gravity waves in the winter thermosphere is originated from the polar night jet in the stratosphere/mesosphere. Moreover, the impacts of thermospheric gravity waves on variability in the ionosphere are investigated. Keywords: vertical coupling processes, atmospheric waves ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-14 - PEM03-15 Japan Geoscience Union Meeting 2016 An analysis on the momentum budget in the MLT region based on satellite and whole atmosphere model data *Ryosuke Yasui1, Kaoru Sato1, Yasunobu Miyoshi2 1.Graduate School of Science, The University of Tokyo, 2.Faculty of science, Kyushu University In the middle atmosphere, gravity waves (GWs), tides (TWs) and Rossby waves (RWs) are dominant. By interacting with the mean flow, these waves maintain the thermal structure considerably different from that expected from a radiative balance. However, the momentum budget of the middle atmosphere has not thoroughly examined particularly for the mesosphere and lower thermosphere (MLT). In this study, the momentum budget in the MLT including piecewise contribution by each wave is examined by analyzing a satellite data and a whole atmosphere model data. An interplay of RWs and GWs is also focused on for the formation of barotropic (BT) /baroclinic (BC) instability. The analysis of the present study is mainly performed for climatology fields for each month in the zonal mean meridional cross-section. Used data are temperature and geopotential heights from Aura MLS observations as the satellite data (MLS data) and the neutral atmosphere data which was obtained by simulation using the GAIA model, which include a coupled neutral and ionized atmospheres from ground to lower thermosphere (LT) as the whole atmospheric model (GAIA data). The analyzed period is about 11 years from 8 August 2004–19 June 2015. First, MLS data are analyzed. Magnitude of potential vorticity (PV) maximizes in low and middle (high) latitudes in the summer (winter) mesosphere. In the poleward side of these maxima, meridional gradient of PV (PVy) is negative, which is a necessary condition of BT/BC instability. EP flux (EPF) is strongly upward and EPF divergence (EPFD) is positive slightly poleward and above the PV maximum (PVM) in the summer mesosphere. Moreover the distribution of the occurrence frequency of positive EPFD accords well with that of negative PVy. These features suggest that RWs are radiated upward from the mesospheric PVM. Second, the momentum budget is analyzed using GAIA data. EPF is divided into TW, RW and GW components. For the RW component, EPFD is significantly positive in the region where PVy is negative in the summer mesosphere. Strong upward EPF above the positive EPFD region is extended up to 0.0001 hPa in the LT. From a spectral analysis in this upward EPF region, it is seen that westward propagating waves having a 1.8 day period and s = 2–4 are dominant. This feature is similar to that of quasi-two day waves detected by previous observations. Moreover the feature that strong upward and equatorward EPF is observed above the negative PVy region suggests that these waves are generated through BT/BC instability. Next, the GW component is examined. GW EPFD is generally positive (negative) in summer hemisphere (SH) (winter hemisphere (WH)) in the MLT. It is seen from the direction of EPF that eastward (westward) waves are dominant in the SH (WH). The downward EPF (i.e. dominance of eastward waves) is particularly strong above the negative PVy region in the SH MLT, suggesting that GWs are generation there. The Richardson number in this region is frequently lower than 1/4, suggesting that the eastward GWs are generated by shear instability. EPFD due to all wave components is mainly positive (negative) in SH (WH) in the MLT. Among these, the GW component is most dominant. The forcing of subgrid-scale GWs (GWFP) is parameterized in the GAIA model. The GWFP maximizes around ~90 km in the upper mesosphere of the both hemispheres. The GWFP is comparable to the EPFD due to all resolved waves although the vertical distribution is different. Last, the relation between GWFP distribution and negative PVy region is examined. GWFP is positive (negative) in low and high latitudes (all latitudes) of the SH (WH) mesosphere, and these maxima correspond to the location of the PVM. It is shown that the PVM is mainly contributed to by N2 in ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-15 - PEM03-15 Japan Geoscience Union Meeting 2016 WH and by both N2 and relative vorticity in SH. In addition, the rate of change of PV due to GWFP is directly estimated. The result indicates that the GWFP is likely responsible for the formation of PVM. Keywords: Middle atmosphere, Rossby wave, Gravity wave, Barotropic / baroclinic instability, Momentum budget ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-15 - PEM03-16 Japan Geoscience Union Meeting 2016 Terahertz Limb Sounder for Lower Thermosphere Wind, Temperature, and Atomic Oxygen Density Measurements *JengHwa Yee1, Dong Wu2, Imran Mehdi3, Erich Schlecht3 1.Applied Physics Laboratory, Johns Hopkins University, 2.NASA Goddard Space Flight Center, 3.NASA Jet Propulsion Laboratory, In this paper, we present the concept of a high-sensitivity heterodyne spectrometer operating at 2.0 Terahertz (THz) for global lower thermospheric neutral wind, temperature and atomic oxygen density measurements from a low earth orbit. The instrument, THz Limb Sounder (TLS) is aimed to provide, for the first time, global neutral wind/temperature/density profile measurements globally during day and night, with focus at altitudes of 100-150 km where most of the ion-neutral energy/momentum couplings take place. TLS is an ambient-temperature Schottky diode based all solid-state heterodyne spectrometer designed to extend the limb sounding technique employed by Microwave Limb Sounder for density/temperature/wind measurements by measuring the Doppler line shape of atomic oxygen (OI) fine structure emission at 2.06THz. This atomic oxygen line emission is very bright and distributed nearly uniformly globally (at all latitudes including highly spatially structured aurora particle precipitation regions) and temporally (at all local times during both day, night, and twilight), thus ideal for thermospheric remote sensing. The instrument concept, measurement methodology, receiver performance, and the expected measurement capability will be presented and discussed in this paper. Keywords: Lower Thermosphere Wind, Temperature, and Density, Remote Sensing Technique and Instrument, TeraHz Spectrometer ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-16 - PEM03-17 Japan Geoscience Union Meeting 2016 A review on recent upper atmosphere atomic oxygen measurements *Martin Kaufmann1, Yajun Zhu2, Manfred Ern1, Martin Riese1 1. Research Centre Julich, Institute for Energy and Climate Research, 2. Research Centre Julich and University of Wuppertal Atomic oxygen is a key player in upper mesosphere and lower thermosphere chemistry, energy balance, and vertical as well as global coupling. In recent years, a few new global datasets of this species have been presented. They are based on airglow measurements from low earth orbit satellites. Surprisingly, the atomic oxygen abundance differs by 30-50% for similar atmospheric conditions. This paper gives an overview on the various atomic oxygen datasets available so far and presents most recent results obtained from measurements of the SCIAMACHY instrument on Envisat. Differences between the datasets are discussed. Keywords: atomic oxygen, mesosphere, thermosphere, coupling, energy balance ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-17 - PEM03-18 Japan Geoscience Union Meeting 2016 Double Crests of Peak Height in the Equatorial Ionospheric F2 Layer Observed by COSMIC *Xiaoli Luan1 1.University of Science and Technology of China For the first time, we report daytime double crests of peak height (hmF2) in the F2 layer based on the COSMIC observations during 2007-2014. Evident double crests of hmF2 occurred at around ±10° geomagnetic latitude (MLAT) with a trough over the magnetic equator at low solar activity and at March equinox. This phenomenon is referred to as an Equatorial Height Anomaly (EHA) of the ionospheric F2 layer. The double crests became less obvious at September equinox and disappeared at solstices. At solstices only one crest was observed in the summer hemisphere, which is probably associated with trans-equatorial neutral winds. In addition, the double EHA crests generally take place during 10:00-14:00 local times. Our results indicate that the EHA favors the conditions of strong vertical plasma drifts and weak trans-equatorial neutral winds during low solar activity. The EHA feature is reproduced by the TIEGCM at March equinox and low solar activity. Keywords: F2 layer peak height, Latitudinal variation, Equatorial anomaly, Ionospheric ceiling ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-18 - PEM03-19 Japan Geoscience Union Meeting 2016 Local time evolution and longitudinal difference of equatorial ionization anomaly in the low-latitude topside ionosphere *Yiding Chen1, Libo Liu1, Huijun Le1, Weixing Wan1 1.Institute of Geology and Geophysics, Chinese Academy of Sciences The latitudinal structure of topside ion density (Ni) was investigated in detail based on the Ni observations of the ROCSAT-1 and DMSP satellites. EIA double-peak structure can exist at 600 km, depending on longitude, local time, season, and solar activity, while it cannot extend up to 840 km even in the case of the strong fountain effect at solar maximum sunset. The complete local time evolution of the EIA at 600 km was presented. The double-peak structure begins to appear at noontime, being later than the appearance of the EIA in F2-peak region. The pronounced EIA induced by the strong prereversal enhancement at solar maximum begins to appear at 19:00 LT and can last to pre-midnight; and EIA crest-to-trough ratio (CTR) reaches a maximum at 20:00 LT, with the largest (lowest) CTR at March equinox (June solstice). EIA structure shows evident longitudinal difference. Pronounced EIA exists around about 100°E at 13:00 LT at the two equinoxes and June solstice, while it exists at more extensive longitudes (about 90°E to 240°E) at December solstice. The trans-equator plasma transport induced by neutral winds can weaken the double-peak structure in the topside ionosphere. The longitudinal difference in the EIA structure at 600 km is related to the longitudinal variations of equatorial upward plasma drift and geomagnetic declination. Keywords: Low-latitude Ionosphere, Topside Ionosphere, Equatorial Ionization Anomaly ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-19 - PEM03-20 Japan Geoscience Union Meeting 2016 Realtime 3D tomography of the ionosphere based on GEONET GPS-TEC *Mamoru Yamamoto1, Syota Suzuki1, Susumu Saito2, Chia-Hung Chen3, Akinori Saito4 1.Research Institute for Sustainable Humanosphere, Kyoto University, 2.Electronic Navigation Research Institute, 3.National Cheng Kung University, 4.Department of Geophysics, Kyoto University Measurement of ionospheric total electron content (TEC) by using the ground-based GPS receivers is now widely used. We refer to it as GPS-TEC. As there are always several GPS satellites available for the measurement, it is a very good tool for constant monitoring of the ionosphere. One of the most dense and wide network of the GPS network is GEONET operated by Geospatial Information Authority of Japan (GSI). This is the network of more than 1200 points over Japan. We have been developing 3D tomography of the ionospheric plasma density from the GEONET data. This tomography technique uses a constrained least squares fit to reconstruct the electron density distributions. Recently we further develop the software system to conduct the GPS-TEC analysis in the realtime basis. In this system we collect “every second” GPS data from GEONET, estimate satellite and receiver biases for true TEC measurement, and obtain 3D tomography reconstruction of the ionosphere every 15 minutes with 10 minutes latency. We will show current status of the 3D tomography analysis and the realtime system. Keywords: 3D tomography, GPS TEC, GEONET, Realtime ionosphere monitoring ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-20 - PEM03-21 Japan Geoscience Union Meeting 2016 Extremely large longitudinal variation of ionospheric bubble generation and its possible relationship with ITCZ *Guozhu Li1, Yuichi Otsuka2, M. A. Abdu3, Mamoru Yamamoto4, Prayitno Abadi5 1.Institute of Geology and Geophysics, Chinese Academy of Sciences, 2.Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan, 3.Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP, Brazil, 4.Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan, 5.Space Science Center, the Indonesian National Institute of Aeronautics and Space (LAPAN), Bandung, Jawa Barat, Indonesia A close link between the atmospheric inter-tropical convergence zone (ITCZ) and ionospheric plasma bubble has been proposed since the last century. But this relationship has often appeared to be less than convincing due to the simultaneous roles played by several other factors, most importantly by the evening pre-reversal enhancement of eastward electric field (PRE) and its associated velocity shear, in shaping the global distribution of ionospheric bubbles. From simultaneous collaborative radar multi-beam steering measurements at Kototabang (0.2°S, 100.3°E) and Sanya (18.4°N, 109.6°E), conducted during September–October of 2012 and 2013, we find that there exists extremely large longitudinal variation in bubble generation but not in bubble occurrence. The total numbers of nights with bubble (i.e., occurrence rates) over the two stations are comparable, but the total number of nights with locally generated bubble (i.e., generation rate) over Kototabang is clearly more than that over Sanya. Further analysis reveals that a more active ITCZ is situated around the longitude of Kototabang. Considering that the two stations are separated only by 9.3° in longitude where the magnetic declination and the magnetic equator offset from the geographic equator are almost the same, the enhanced ionospheric bubble generation over Kototabang may be explained by upward propagating gravity waves (GWs) which could be generated frequently in the more active ITCZ and provide the seeding source for bubble development. Keywords: ionospheric plasma bubble, atmospheric inter-tropical convergence zone, gravity wave ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-21 - PEM03-22 Japan Geoscience Union Meeting 2016 Equinoctial asymmetry in the east-west distribution of scintillation occurrence observed by GPS receivers in Indonesia *Prayitno Abadi1,2, Yuichi Otsuka1, Kazuo Shiokawa1, Shin Suzuki3, Susumu Saito4, Hermann Luehr5, Jaeheung Park6, Huixin Liu7 1.Institute for Space-Earth Environmental Research (ISEE) , Nagoya University, Japan, 2.Space Science Center, Indonesian National Institute of Aeronautics and Space (LAPAN), Indonesia, 3.Faculty of Regional Policy, Aichi University, Japan, 4.Electronic Navigation Research Institute, Tokyo, Japan, 5.Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, 6.Korea Astronomy and Space Science Institute, 7.Earth and Planetary Science Division, Kyushu University SERC, Kyushu University We used GPS receivers installed in Pontianak (0.02°S, 109.3°E; 9.8°S mag. Lat.) and Bandung (6.9°S, 107.6°E; 16.7°S mag. Lat), Indonesia to observe azimuthal dependence of GPS-L1 scintillation occurrence rate. Crest of the equatorial anomaly region is located between both sites. We focus on analyzing east-west distribution of scintillation occurrences in equinox months. We collected scintillation data as indicated by S4 index from those receivers for March and September from 2011 to 2015. Our findings statistically emphasized that scintillation occurrence rate is higher in the westward direction than that in eastward direction in March equinox. This east-west difference of scintillation occurrence is more distinct in March equinox than September equinox. In September equinox, the occurrence rate is almost comparable between westward and eastward direction. We can speculate that the equinoctial asymmetry in east-west distribution of scintillation occurrence could be likely caused by westward tilt of plasma bubble extending to higher altitudes/latitude, and that the plasma bubbles are more tilted westward in March equinox than in September equinox. We have analyzed zonal irregularity drift velocity observed by closely-spaced GPS receivers at Kototabang (0.2°S, 100.3°E; 9.9°S mag. Lat.), Indonesia for the same observation period. The results showed that eastward drift velocity decreases with increasing magnetic latitudes, and that the latitudinal gradient of eastward drift in March equinox is larger than in September equinox. Additionally, we used in-situ measurement of zonal wind velocity at ~400 km of altitude by CHAMP satellite in March and September from 2001 to 2005 for longitude 95-105°E. We found that latitudinal eastward wind velocity also show decrease of the magnitude with the increasing magnetic latitudes. The latitudinal gradient of eastward wind in March is larger than the latitudinal gradient in September. Thus, in March equinox, the large latitudinal gradient of irregularity drift and eastward wind velocity could be responsible for further westward tilt of plasma bubble extending to higher altitudes/latitudes. Consequently, the equinoctial asymmetry of east-west distribution of scintillation could be caused by the equinoctial asymmetry of tilted westward structure of plasma bubble. Keywords: equatorial ionosphere, plasma bubble, irregularity, scintillation, equinoctial asymmetry, coupling neutral-plasma ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-22 - PEM03-23 Japan Geoscience Union Meeting 2016 Multiple excitation of large-scale traveling atmospheric disturbances (TADs) by solar wind fluctuations *Jianpeng Guo1 1.National Space Science Center, Chinese Academy of Sciences Fluctuations on timescales of minutes to hours are common in the solar wind. When the fluctuations encounter the Earth, they could excite gravity waves in the auroral regions. These gravity waves, particularly large-scale (> ~1000 km) gravity waves, will give rise to traveling atmospheric disturbances (TADs) with typical amplitudes of 20~40% in the upper thermosphere. We report here the detection of multiple excitation of large-scale TADs by Alfvén waves embedded in high-speed solar wind streams, and also by interacting coronal mass ejections. Keywords: solar wind fluctuations, gravity waves, thermosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-23 - PEM03-24 Japan Geoscience Union Meeting 2016 A link between high-speed solar wind streams and extratropical cyclones *Paul Prikryl1,2, Koki Iwao3, Takumi Tsukijihara4, Donald B. Muldrew5, Vojto Rušin6, Milan Rybanský7 , Robert Bruntz8 1.Geomagnetic Laboratory, Natural Resources Canada, Ottawa, ON, Canada, 2.Physics Department, University of New Brunswick, Fredericton, NB, Canada, 3.National College of Technology, Kumamoto College, Yatsushiro, Japan, 4.Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan, 5.Emeritus, Communications Research Centre, Ottawa, ON, Canada, 6.Astronomical Institute, Slovak Academy of Sciences, Tatranská Lomnica, Slovakia, 7.Slovak Central Observatory, Hurbanovo, Slovakia, 8.Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA Databases of extratropical-cyclone tracks obtained from two meteorological reanalysis datasets are used in superposed epoch analysis of time series of solar wind plasma parameters and green-coronal emission line intensity. The time series are keyed to times of maximum growth of explosively developing extratropical cyclones during northern and southern winters. The new statistical evidence corroborates the previously published results (Prikryl et al., Ann. Geophys., 27, 1-30, 2009). This evidence shows that explosive extratropical cyclones tend to occur after arrivals of solar wind disturbances such as high-speed solar wind streams from coronal holes when large amplitude magneto-hydrodynamic waves couple to the magnetosphere-ionosphere system. These MHD waves modulate Joule heating and/or Lorentz forcing of the high-latitude thermosphere generating medium-scale atmospheric gravity waves. Ray tracing of aurorally-generated gravity waves show that the gravity waves propagate upward and downward through the atmosphere. Simulations of gravity wave propagation in a model atmosphere using the Transfer Function Model (TFM) (Mayr et al., Space Sci. Rev., 54, 297–375, 1990) show that propagating waves originating in the thermosphere can excite a spectrum of gravity waves in the lower atmosphere. At the tropospheric level, in spite of significantly reduced amplitudes, they can provide a lift of unstable air to release the moist symmetric instability thus initiating slantwise convection and forming cloud/precipitation bands (Prikryl et al., Ann. Geophys., 27, 31-57, 2009). The release of latent heat is known to provide energy for rapid development and intensification of extratropical cyclones. Since 2009, Japan Meteorological Agency has archived detailed annual reports on calamitous severe weather events occurring nation-wide (http://www.jma.go.jp/jma/menu/menureport.html). The starting dates of the events attributed to low pressure systems are used as key times in the superposed epoch analysis of solar wind plasma parameters and green solar corona intensity. It is observed that the events of heavy rain or snow, strong wind and high ocean waves caused by low pressure storms, particularly in winter, tend to follow arrivals of high-speed solar wind. This is consistent with the statistical evidence based on the study of explosive extratropical cyclones in relation to solar wind. Keywords: High-speed solar wind streams, Atmospheric gravity waves, Extratropical cyclones ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-24 - PEM03-25 Japan Geoscience Union Meeting 2016 Characteristics of mesosphere echoes over Antarctica obtained using PANSY and MF radars *Masaki Tsutsumi1,4, Kaoru Sato2, Toru Sato3, Takuji Nakamura1,4, Koji Nishimura1,4, Yoshihiro Tomikawa1,4, Masashi Kohma2 1.National Institute of Polar Research, 2.1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 3.Department of Communications and Computer Engineering Graduate School of Informatics, Kyoto University, 4.The Graduate University for Advanced Studies In the polar region characteristic radar echoes are observed from the mesosphere by using a VHF system. The nature of the echoes is distinctively different between summer and winter and those echoes are called Polar Mesosphere Summer Echoes (PMSEs) and Polar Mesosphere Winter Echoes (PMWEs), respectively. Since the PMSEs are usually very strong and can be easily measured with a small radar system, their nature is relatively well understood. On the other hand PMWEs are much weaker and they are still only poorly understood. The PANSY radar (47MHz) at Syowa station (69S) is the only large aperture atmospheric radar in the Antarctic, and can continuously survey the dynamics of the middle atmosphere with high time and height resolutions [Sato et al., 2014]. Nishiyama et al [2014] reported the first study of PMWEs using PANSY radar and showed a seasonal and local time dependence of these echoes. An MF radar system (2.4MHz) is co-located at Syowa, and has been operating for mesosphere and lower thermosphere observations. Although the MF radar has only a much poorer height resolution and is incapable of vertical wind measurement, it can almost continuously measure mesosphere day and night. In this study the nature of the mesosphere echoes, mainly PMWEs, are being studied using the two radars based on the observation made in 2015. These radars are operated using largely different radio frequencies and can provide complementary information with each other such as wind velocities and also echo scattering mechanisms. Horizontal wind velocities have been compared between the two radars with a great care mostly in the MF radar winds in order to avoid possible biases inherent in the correlation analysis technique employed for the MF radar wind measurement. A careful analysis has shown that the horizontal wind velocities agree well between the two systems with a high correlation coefficient around 0.8 throughout the height region of 65-85km. Aspect sensitivities estimated using the MF radar data indicate that the winter time MF echoes in the lower mesosphere are more isotropic in winter than in summer, suggesting that the winter echoes are scattered by isotropic turbulences. A candidate that generates such isotropic structures is thought to be gravity waves, whose activity in the Antarctic mesosphere is maximized in winter [Dowdy et al., 2007; Yasui et al., 2016]. The height region of the low aspect sensitivity mostly corresponds to that of PMWEs, and this further suggests a possible connection between PMWEs and gravity wave activity. Aspect sensitivities based on the PANSY data are also to be analyzed and presented. Keywords: Antarctic, PMWEs, MST radar, atmospheric gravity waves ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-25 - PEM03-26 Japan Geoscience Union Meeting 2016 Gravity Wave Instability Dynamics in Mesospheric Stratification and Shear Environments *Tyler Mixa1,2, David Fritts2, Brian Laughman2, Ling Wang2, Lakshmi Kantha1 1.University of Colorado Boulder, Boulder, CO, USA, 2.GATS-inc, Boulder, CO, USA An anelastic numerical model is used to explore gravity wave instability dynamics in variable stratification and shear environments in the mesosphere and lower thermosphere (MLT). Recent computational advances facilitate the characterization of localized gravity wave packets in a deep atmosphere, enabling realistic amplitude evolution and enhanced sensitivity to transient nonlinear dynamics. The results reveal that gravity wave packets impinging on a sheet of high stratification and shear enable local Kelvin-Helmholtz instabilities (KHI) where gravity wave vertical displacements approach their maxima and mean and gravity wave shears combine. The KHI arise at smaller scales and evolve to larger scales with time, as seen in lidar, radar, and airglow observations. Such events tend to be highly localized and thus yield local energy and momentum deposition expected to have strong influences throughout the mesosphere, thermosphere, and ionosphere (MTI) region. These simulations illuminate one of the major mechanisms driving turbulence and mixing in the MLT at scales that are challenging or impossible to describe quantitatively with existing measurement capabilities. Keywords: Atmospheric Gravity Waves, Gravity Wave Instability Dynamics ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-26 - PEM03-P01 Japan Geoscience Union Meeting 2016 Equatorial Atmospheric Kelvin Waves during 2014-2016 El Niño episodes andtheir effect on Stratospheric QBO *Chen-Jeih Pan1, S.S. Yang1, Uma Das1 1.Institute of Space Science, National Central University Equatorial atmospheric Kelvin waves are investigated during positive El Niño Southern Oscillation (ENSO) episodes using temperature data retrieved from GPS Radio Occultation (RO) observations of FORMOSAT-3/COSMIC 5 during the period from August 2006 to April 2016. Enhanced Kelvin wave activity is observed during the El Niño episodes of 2010 and 2014-2016 and it is also observed that the Kelvin wave amplitudes correlate with the Niño 3.4 index and also with outgoing longwave radiation and trade wind index. This study indicates that the enhanced equatorial atmospheric Kelvin wave activity might be produced by geophysical processes that were involved in the onset and development of the El Niño episode. Further, easterly winds above the tropopause during this period favoured the vertically upward propagation of these waves that induced a fast descending westerly regime by the end of 2010 but showing different behaviors during 2014-2016 period.The current study presents observational evidence of enhanced Kelvin wave activity during El Niño that has affected the stratospheric quasi-biennial oscillation (QBO) through wave-mean flow interactions. Detailed comparison between the ENSO episodes of 2010 and 2014-2016 will be investigated in this study. Keywords: El Niño Southern Oscillation , quasi-biennial oscillation (QBO) ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P01 - PEM03-P02 Japan Geoscience Union Meeting 2016 Analysis of the Distribution and Controlling Factors in the Atmospheric Gravity Wave Potential Energy *Shih-Sian Yang1, Chen-Jeih Pan1, Uma Das1, H. C. Lai2 1.Institute of Space Science, National Central University, Taiwan, 2.Department of Engineering & Management of Advanced Technology, Chang Jung Christian University, Taiwan In the past years, global morphology and climatology of gravity waves have been widely studied and the effects of topography and convection systems have been evaluated, but the complete gravity wave distribution could not be explained by these effects. To find the missing controlling factors, a series of synoptic scale analyses is performed in the present study to investigate relationships between synoptic scale factors and potential energy (Ep) associated with gravity waves. Global distribution of Ep during a 12-year period from 2002 to 2013 is derived using temperature profiles retrieved from observations of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. Synoptic scale factors obtained from ECMWF Interim reanalysis data are employed to investigate the correlation between synoptic systems and Ep. It is found that Ep values are high around extratropical cyclones over mid-latitudes (30° –60°) and around the Intertropical Convergence Zone (ITCZ) over low-latitudes (10° –30°). Ep values are low around subtropical highs over both mid- and low-latitudes. This is the first time that a synoptic scale analysis of Ep distribution is performed, and the influence of synoptic scale factors on Ep confirmed. Keywords: gravity waves, potential energy, synoptic scale factors, TIMED/SABER ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P02 - PEM03-P03 Japan Geoscience Union Meeting 2016 Study of vertical / seasonal variation of gravity wave in the height range of 15-70km over Syowa Station in Antarctica using Rayleigh/Raman lidar *Masaru Kogure1, Takuji Nakamura1,2, Mitsumu K. Ejiri1,2, Takanori Nishiyama1,2, Yoshihiro Tomikawa1,2 , Masaki Tsutsumi1,2 1.The Graduate University for Advanced Studies, 2.National Institute of Polar Research The gravity waves are generated in the lower atmosphere, propagate upward and transfer momentum and energy to the middle atmosphere. It has been found that the gravity waves induce large scale meridional circulation and drive the middle atmosphere away from radiative equilibrium [Lindzen, 1981; Holton, 1982; Matsuno, 1982]. However, we have not completely known the quantification of gravity wave roles in the middle atmospheric circulation. A Rayleigh/Raman(RR) lidar was installed in January 2011 at Syowa Station, Antarctica (69°S,40°E). The lidar has measured temperature profiles between 5 and 80 km for more than 350 nights (before the end of October in 2014). In this study, we investigated monthly mean gravity wave potential energy (Ep) in the height range of 15-70 km from May 2011 to October 2013. Above 35km altitude, Ep was maximized during winter. The seasonal dependence of Ep over Syowa was similar to Ep observed at Davis(69°S,79°E) [Alexander et al., 2011]. Below 35 km altitude, Ep was enhanced in around May, and did not decrease in September. Almost all monthly mean profiles have constant slope above 30 km altitude. Ep increases exponentially with height (increasing rate is approximately exp(z/H); H~7 km is scale height). Furthermore, almost all Ep profiles have a local minimum around 25 km altitude and a local maximum around 20 km altitude. In October 2012, Ep is significantly different from the other Ep profiles. As a result of comparison between the Ep profiles and zonal wind in the NASA MERRA reanalysis data, the reason was probably that weak zonal wind layer in 2012 descends earlier than the other years. Keywords: gravity wave, middle atmosphere, lidar ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P03 - PEM03-P04 Japan Geoscience Union Meeting 2016 Evaluation of Global Mean Temperature Cooling in lower thermosphere just after Stratospheric Sudden Warming due to Tidal wave’s vertical thermal advection using GAIA model *Kenshi Goya1, Huixin Liu2, Yasunobu Miyoshi2, Saburo Miyahara3 1.Graduate School of Science, Kyushu University ICSWSE, 2.Graduate School of Science, Kyushu University, 3.Kyushu University Saburo MIYAHARA and Ying-Wen CHEN reported that Kyushu-GCM data analysis showed Variation of Global Mean Temperature connected with Stratospheric Sudden Warming (SSW) at 2015 Spring conference of the Meteorological Society of Japan. The report concludes that vertical thermal advection of semi-diurnal tide ( zonal wave number = 2 ) causes about 50 % of Global Mean Temperature Cooling in the lower thermosphere. Kyushu-GCM can express meteorological phenomena from the ground to 150 km height. In order to verify its conclusion of Kyushu-GCM case in higher atmosphere than 150 km, GAIA ( 75 layers ) model is used. It can describe meteorological states up to 500 km height and then the analysis has been done about the Global Mean Temperature Cooling in the lower thermosphere just after SSW caused by tidal wave’s vertical thermal advection. Therefore it has been confirmed that the semi-diurnal tide (zonal wave number = 2) disturbance dominantly contributes to the cooling as same as the case of Kyushu-GCM up to about 200 km height. The semi-diurnal tide works cooling higher than 200 km, but diurnal tide ( zonal wave number =1 ) works strongly warming and net migrating tide disturbance also works warming. Then in this case the global mean temperature cooling in the lower thermosphere cannot be explained due to the vertical thermal advection of tidal wave disturbance. All non-migrating tide almost does not only work cooling but also warming. Waltersheid (1981) proved theoretically that vertical thermal advection of internal gravity wave disturbance caused cooling in lower thermosphere. Thus this research result may suggest that many internal gravity waves are dominant and work cooling in the lower thermosphere. Vertical resolution of GAIA(75 layers) is much lower than Kyushu-GCM( 250 layers ). The analyses of GAIA(150 layers) will be also shown at the conference hall. Keywords: Stratospheric Sudden Warming, Atmospheric Tidal Wave, GAIA model ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P04 - PEM03-P05 Japan Geoscience Union Meeting 2016 Measurement of momentum flux Using two meteor radars in Indonesia Naoki Matsumoto1, Atsuki Shinbori1, Dennis M Riggin2, *Toshitaka Tsuda1 1.Research Institute for Sustainable Humanosphere (RISH), Kyoto University, 2.GATS, Inc. Two nearly identical meteor radars were operated at Koto Tabang (0.20oS, 100.32oE), western Sumatra, and Biak (1.17oS, 136,10oE), western Papua in Indonesia, separated by approximately 4,000 km in longitude on the equator. The zonal and meridional momentum flux, u’w’ and v’w’ , where u, v and w are the eastward, northward and vertical wind velocity components, respectively, were estimated at 86 to 94 km altitudes using the meteor radar data by applying a method proposed by Hocking [2005]. The observed u’w’ at the two sites agreed reasonably well at 86, 90 and 94 km during the observation periods when the data acquisition rate was sufficiently large enough. Variations of v’w’ was consistent between 86, 90 and 94 km altitudes at both sites. The climatological variation of the monthly averaged u’w’ and v’w’ was investigated using the long-term radar data at Koto Tabang from November 2002 to November 2013. The seasonal variations of u’w’ and v’w’ showed a repeatable semiannual and annual cycles, respectively. u’w’ showed eastward values in February-April and July-September, and v’w’ was northward in June to August at 90-94 km, which were generally anti-phase with the mean zonal and meridional winds, having the same periodicity. Our results suggest the usefulness of the Hocking method. Keywords: Meteor radar, Momentum flux, Mesosphere and lower thermosphere, Hocking method, Equator, Semi-annual variation ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P05 - PEM03-P06 Japan Geoscience Union Meeting 2016 Tidal modulation of mesospheric gravity waves observed with MF radar at Poker Flat, and Tromsø *Yasuhiro Murayama1, Takenari Kinoshita1, Seiji Kawamura1, Satonori Nozawa2, Chris Hall3 1.National Institute of Information and Communications Technology, 2.Nagoya University, 3.The Arctic University of Norway The neutral wind velocity data from mesosphere to lower thermosphere observed by MF radars at Poker Flat in Alaska and at Tromso in Norway has been observed since the late 1990s. The present study examines the relation between short-period mesospheric gravity wave activities and the background state including diurnal and semidiurnal tides using these MF radars' data for 10 years of 1999~2008. Observed wind velocities having the 1~4 hour period components are analyzed as short-period gravity waves and those having harmonic components with periods of 48, 24, 12, and 8 hours are calculated every 30 minutes. The previous study in IUGG2015 showed that the maximum of GW-KE occurs at Poker Flat when zonal wind is easterly from November to December and zonal wind transitions from easterly to westerly from January to February and from May to August from climatological 1-day composite plots of 12 hour components of zonal wind and GW-KE. The results of Tromso showed that the maximum of GW-KE occurs at local time when zonal wind is westerly from November to February and easterly from May to September. Next, considering the physical mechanisms under these relations, we confirmed that these relations can be explained by the critical level filtering of gravity waves except for summer cases at Poker Flat. We plan to investigate the summer relation at Poker Flat in more detail and discuss another physical mechanism. Keywords: Atmospheric Gravity Wave, Atmospheric Tide, Mesosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P06 - PEM03-P07 Japan Geoscience Union Meeting 2016 Recent Progress on Advanced Ionospheric Probe Onboard FORMOSAT-5 Satellite *Chi-Kuang Chao1, Zai-Wun Lin1, Ya-Chih Mao1 1.Graduate Institute of Space Science, National Central University Advanced Ionospheric Probe (AIP) is a piggyback science payload developed by National Central University for FORMOSAT-5 satellite since 12 January 2012. The AIP is an all-in-one plasma sensor to measure ionospheric plasma concentrations, velocities, or temperatures in a time-sharing way. Meanwhile, the AIP is capable of measuring ionospheric plasma irregularities with sampling rate up to 8,192 Hz over a wide range of spatial scales. Electroformed gold grids used in the AIP can reduce quasi-hysteresis effect on current-voltage curves in a plasma injection test and approximate ideal electrical potential surfaces for accurate data available in the future. The AIP flight model has passed through preliminary and critical design review, functional and environmental tests, and then was delivered to the NSPO on 8 October 2013. It is scheduled to launch into a low Earth orbit on a Falcon 9 rocket manufactured by Space Exploration Technologies Corp. from Vandenberg Air Force Base in the 2nd quarter 2016 to carry out a two-year scientific mission on space weather and seismic precursors. At the beginning the AIP will be routinely operated within ±75° latitude in the night-side sector to meet a 5-W limit in average power per orbit due to high power consumption and a heat dissipation issue. Up to 1.5 gigabits per day in data storage, the AIP is capable to perform 8,192 electric current readings per second with duty cycle under 10% to resolve fine structure of equatorial ionospheric plasma irregularities within ±18° latitude. Keywords: AIP, FORMOSAT-5, Ionosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P07 - PEM03-P08 Japan Geoscience Union Meeting 2016 Conjugate observations of low-latitude travelling ionospheric disturbances by a 630-nm airglow imager at Indonesia and the CHAMP satellite *Aysegul Ceren Moral1, Kazuo Shiokawa1, Shin Suzuki2, Huixin Liu3, Yuichi Otsuka1, Clara Yono Yatini4 1.Institute for Space-Earth Enviromental Research, Nagoya University, 2.Faculty of Regional Policy, Aichi University, 3.Dept. of Earth and Planetary Science, Faculty of Science, Kyushu University, 4.Space Science Center, the Indonesian National Institute of Aeronautics and Space (LAPAN) We report the first comparison of ground and satellite measurements of equatorial travelling ionospheric disturbances (TIDs) by using a 630-nm airglow imager and the CHAMP satellite. The airglow images are obtained at Kototabang (KTB), Indonesia (geographic coordinates: 0.2S, 100.3E, geomagnetic latitude: 10.6S), during a 7-year period from October 2002 to October 2009. Only three TID events with ground and satellite conjugate measurements are found on April 30, 2006 (event 1), September 28, 2006 (event 2) and April 12, 2004 (event 3). All three events were southward-moving structures in 630-nm airglow images. The events 1 and 2 are single pulse with horizontal scales of ~500-1000 km. The event 3 show three wave fronts with horizontal scale size of 500-700 km. For event 2, the neutral density shows in-phase variations with the airglow intensity. However for events 1 and 3, they are out of phase. The relation between electron density and airglow intensity is out of phase for event 1, while their relationship are unclear for event 2 and 3, suggesting that ionospheric plasma variation is not the cause of the observed TID. If the TIDs are caused by gravity waves in the thermosphere, in and out of phase relationships between neutral density at an altitude of 400 km at CHAMP and airglow layer at 250 km, should depend on the vertical wavelength of the gravity wave, which is highly affected by background wind. We estimate possible vertical wavelengths for those events to explain the observed phase relationships between neutral density and airglow intensity. Keywords: Travelling Ionospheric Disturbances, CHAMP, Airglow Imager ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P08 - PEM03-P09 Japan Geoscience Union Meeting 2016 The Occultation TEC Assimilated to NCAR/TIE-GCM to Simulate the Ionosphere During the Storm Time *Ming-Quey Chen1 1.Graduate Institute of Space Science, National Central University We will construct a data assimilation model with the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) for the ionosphere by assimilating the FORMOSAT-3 occultation total electron contents (OTEC). The TIE-GCM was developed by NCAR/HAO is a self-consistently electrodynamics coupled thermosphere and ionosphere model subjected by a few parameters with the lower and upper boundary conditions to describe the dynamics of the ionosphere and the thermosphere. The measured occultation total electron contents (OTEC) along the light path from GPS to LEO satellites could be assimilated with the TIE-GCM as a realistic model for the space weather in the ionosphere. We assimilated the FORMOSAT-3 OTEC data with TIE-GCM to optimize the parameters for atmospheric tides at lower boundary used in the model that improved the simulation of the electron density distribution in geomagnetic quiet days. The assimilated OTEC data during the geomagnetic storm time will optimize the sensitive physical control parameters of the model such as hemispheric particle participation power (HP), polar cap potential drop (CP). We simulate the ionosphere in storm time in the day Sep. 09, 2011 with the assimilated data with 3 hours per cycle. The optimized time dependent parameters, HP and CP, used in TIE-GCM will be compared with the values in the geophysical indices database (GPI). ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P09 - PEM03-P10 Japan Geoscience Union Meeting 2016 Time and height variability of temparature in Mesosphere and Lower Thermosphere region based on resonance scattering lidar measurement at NIPR (36°N, 140°E) *Takanori Nishiyama1,2, Mitsumu K. Ejiri1,2, Takuo T. Tsuda3, Katsuhiko Tsuno1,6, Makoto Abo4, Takuya Kawahara5, Takayo Ogawa6, Satoshi Wada6, Takuji Nakamura1,2 1.National Institute of Polar Research, 2.SOKENDAI (The Graduate University for Advanced Studies), 3.The University of Electro-Communications, 4.Graduate School of System Design, Tokyo Metropolitan University, 5.Faculty of Engineering, Shinshu University, 6.RIKEN The National Institute of Polar Research (NIPR) is leading a six year prioritized project of the Antarctic research observations since 2010. One of the sub-projects is entitled ‘the global environmental change revealed through the Antarctic middle and upper atmosphere’. As a part of the sub-project, a Rayleigh/Raman lidar (RR lidar) was installed at Syowa, Antarctica (69S, 39E) in January, 2011. The operation has been conducted since February 2011 and the RR lidar has kept measuring temperature profiles continuously between approximately 10 and 80 km for almost 3 years. In order to extend the height coverage to include mesosphere and lower thermosphere region, a new resonance scattering lidar system with tunable wavelengths is developed at NIPR in Tachikawa (35.7N, 139.4E). The lidar transmitter is based on injection-seeded, pulsed alexandrite laser for 768-788 nm (fundamental wavelengths) and a second- harmonic generation (SHG) unit for 384-394 nm (second harmonic wavelengths). The laser wavelengths are tuned into the resonance wavelengths by a wavemeter that is calibrated and validated using a wavelength-stabilized He-Ne laser and a potassium vapor cell for doppler-free spectroscopy. This lidar has capabilities to measure density variations of minor constituents such as atomic iron (Fe, 386 nm), atomic potassium (K, 770 nm), calcium ion (Ca+, 393 nm), and nitrogen ion (N2+, 390, 391 nm) and temperature profiles in the mesosphere and lower thermosphere (MLT) region. It can also estimate temperature profiles from the upper Storatosphere to the lower mesosphere using signals of Rayleigh scattering. In this presentation, we will presnet time and height variability of temparature in the MLT region based on campaign observation in winter 2015-2016 focusing on Sudden Stratospheric Warming (SSW) impact on dyanmics in the MLT region. In addition, the obtained temperature profiles are validated by comparisons to those obatined from satellites data such as Aura/MLS. In addition, dynamical and/or chemical response to SSW and sporadic E-layer in MLT region are discussed using neutral Fe atom density data. Keywords: the Mesosphere and Lower Theremosphere, Temperature, Sudden Stratospheric Warming ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P10 - PEM03-P11 Japan Geoscience Union Meeting 2016 Fine structures in the E-region plasma density of the ionosphere observed by a Ca+ resonance scattering lidar observation *Mitsumu K. Ejiri1, Takanori Nishiyama1, Takuo T. Tsuda2, Makoto Abo3, Katsuhiko Tsuno4, Satoshi Wada4, Takayo Ogawa4, Takuya Kawahara5, Takuji Nakamura1 1.National Institute of Polar Research, 2.The University of Electro-Communications, 3.Graduate School of System Design, Tokyo Metropolitan University, 4.RIKEN, 5.Faculty of Engineering, Shinshu University The National Institute of Polar Research (NIPR) is developing a new resonance scattering lidar with multiple wavelengths to install and operate it at Syowa, Antarctica. The lidar will observe temperature profiles and variations of minor constituents such as Fe, K, Ca+, and aurorally excited N2+ in the mesosphere and lower thermosphere. In August 2014, it received the first light from Ca+ in a sporadic E layer. After that, we increase the resolution of the Ca+ observation and have succeeded in getting the Ca+ profile with time/height resolution of 5 sec/15 m. As a result of the high resolution observations, fine structures in a sporadic E layer with a vertical width of only 1 –2 km have become detectable clearly. In this presentation, we will show the observed fine structures and discuss atmospheric instabilities in the E-region plasma. Keywords: resonance scattering lidar, Ca+, fine structure, Sporadic E layer, interaction of neutral and plasma atmospheres ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P11 - PEM03-P12 Japan Geoscience Union Meeting 2016 First nadir imaging of medium-scale traveling ionospheric disturbances by the spectrographic imager on International Space Station *Michi Nishioka1, Akinori Saito2, Tatsuhiro Yokoyama1, Takuya Tsugawa1, Takeshi Sakanoi3, Yusuke Akiya2, Yuichi Otsuka4, Mamoru Ishii1 1.National Institute of Information and Communications Technology, 2.Graduate School of Science, Kyoto University, 3.Graduate School of Science, Tohoku University, 4.Nagoya University, Institute for Space-Earth Environmental Research Medium-scale traveling ionospheric disturbances (MSTIDs) at mid-latitudes are wave-like structures of the ionosphere, which has been mainly observed by ground-based instruments. It is more challenging to observe MSTIDs from the space while it can clarify spatiotemporal characteristics of MSTIDs. In this presentation, we show the first result of nadir imaging of MSTIDs by the Visible and near-Infrared Spectral Imager (VISI). VISI is one of the instruments of the ISS-IMAP (International Space Station-Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping) mission, which is designed to measure three nightglow emissions; O (630nm), OH Meinel band (730 nm), and O2 atmospheric band (762 nm), with two field of views (+/-45 deg. to nadir). Using 630-nm airglow data of an ionospheric observation mode, MSTIDs structures were successfully detected on May 22, 2014. Horizontal wavelengths of the MSTIDs were 200-500km, which agreed with those observed by ground-based instruments. The peak-to-peak amplitude of MSTIDs observed by the forward (backward) field of views were about 40% (60%) of the background. The difference of the ratios indicates the geomagnetic field-aligned structure of the MSTIDs. Keywords: nadir imaging, 630nm airglow, medium scale traveling ionospheric disturbance ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P12 - PEM03-P13 Japan Geoscience Union Meeting 2016 Coseismic ionospheric disturbances at different altitudes observed with HF Doppler Kazuto Takaboshi1, *Hiroyuki Nakata1, Toshiaki Takano1, Ichiro Tomizawa2 1.Graduate School of Engineering, Chiba University, 2.Center for Space Science and Radio Engineering, The University of Electro-Communications Many studies have reported that ionospheric disturbances occur after large earthquakes. One of the main causes for these disturbances is acoustic wave excited by Rayleigh wave propagated on the ground from the epicenter. The acoustic wave perturbes ionospheric electron density in propagating the ionosphere. Several observations, such as GPS, HF Doppler, the ionogram, observed the ionospheric perturbations at appropriate altitudes for each observations. However, there are few reports for the direct demonstration of vertical propagation of acoustic waves using the single observation. Here, we have observed ionospheric disturbances at the different altitude simultaneously using HF Doppler system (HFD). In this system, radio waves at four different frequencies are observed, implying that the ionospheric perturbations at up to four different altitudes are observed by this system. In examining earthquakes occurred around Japan since 2003, we have found 3 events in which the ionospheric perturbations were observed with the multiple frequencies. From their wave forms, the higher components of the perturbations decay as the altitude is higher. In conjunction with the seismometer data observed below the reflection point of the HFD radio waves, the amplification ratio of the atmospheric wave from ground to the ionosphere have calculated in 3 bands (10.0-25.6, 25.6-45.5, and 45.5-76.9 mHz). Theoretical amplification ratio were also calculated based on energy conservation law, considering absorption by viscosity, thermal conductivity, and relaxation losses of atmosphere (Chum et al., 2012). In comparison of the theoretical amplification ratio, that determined by HFD is rather smaller. However, their height profiles are qualitatively consistent each other; higher frequency components are more greatly damped in at high altitude. There might be the reasons for this difference; attenuations of wave energy that is not considered, differences between model parameters and real values, and lesser conversion efficiency when ground motions excite infrasound waves. Keywords: Ionospheric perturbation, earthquake, HF Doppler, acoustic wave ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P13 - PEM03-P14 Japan Geoscience Union Meeting 2016 Plasma Depletion Bays in the Equatorial Ionosphere Observed by TIMED and FORMOSAT3/COSMIC during 2007-2015 *FUYUAN CHANG1, Jann-Yenq Liu1 1.Graduate Institute of Space Science, National Central University, Taiwan An interesting new feature of three Northern (one Southern) ionospheric plasma depletion bays over the magnetic equator is for the first time found in airglow emissions of 135.6 nm by TIMED/GUVI in May (January) of 2007. Electron density profiles derived from FORMOSAT3/COSMIC are further used to study diurnal, altitude, seasonal, longitudinal, and solar activity variations of the plasma depletion bays. Results show that the plasma depletion bays become the most prominent at 250-300 km altitude around the midnight during the low solar activity year. The three (one) bays appear between 60W-180E (80W-150W) during April-September, especially May (October-March). Model simulations suggest that the trans-equatorial neutral wind in the thermosphere should play an important role. Keywords: FORMOSAT3/COSMIC, TIMED/GUVI, IONOSPHERE ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P14 - PEM03-P15 Japan Geoscience Union Meeting 2016 Seasonal variation of the equatorial wind jet at 250 km and 400 km: GOCE and CHAMP observations *Huixin Liu1, J. Nakashima1, Eelco Doornbos2 1.Earth and Planetary Science Division, Kyushu University , 2.Technical University of Delft, the Netherland By using long-term in-situ wind observations from the GOCE satellite at 250 km, and the CHAMP satellite at ~400 km, this study examine the seasonal variation of the equatorial wind jet previously reported using short-term CHAMP and DE-2 satellite observations. The results show that the wind jet exists at both altitudes, and experiences similar seasonal variations. The wind jet is found to be strongest around the September equinox, and disappears around the June solstice at both altitudes. The jet shows little solar cycle and geomagnetic activity dependence. These seasonal variations are interpreted in the framework of ion-neutral interaction. Keywords: wind jet, thermosphere wind, ion-neutral coupling ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P15 - PEM03-P16 Japan Geoscience Union Meeting 2016 Long-term variation of ionospheric electric fields as seen in the amplitude of geomagnetic solar quiet daily variation *Atsuki Shinbori1, Yukinobu Koyama2, Masahito Nose3, Tomoaki Hori4, Yuichi Otsuka4 1.Research Institute for Sustainable Humanosphere (RISH), Kyoto University, 2.Research Organization of Information and Systems (ROIS), 3.World Data Center for Geomagnetism, Kyoto University, 4.Institute for Space-Earth Environment Research (ISEE), Nagoya University Geomagnetic solar quiet (Sq) daily variation is generated by the large-scale ionospheric currents flowing in the E-region of the ionosphere. The ionospheric currents produce positive and negative variations of the H-component of geomagnetic field around the noon in the equatorial and middle-latitude regions, respectively. According to Ohm’s law, the dependent variables of the Sq amplitude consist of ionospheric conductivity, polarization electric field and dynamo field. Therefore, to investigate the long-term variation of the Sq amplitude is important for understanding the long-term variation in the ionosphere and upper atmosphere. Many researches of the long-term variation of the Sq amplitude on the basis of global observation and model have been made so far. However, characteristics of the long-term variation of global ionospheric Sq electric field remain unknown due to the shortage of long-term ionospheric conductivity analysis at many geomagnetic stations. In this study, we investigate the characteristics of long-term variation of global Sq ionospheric electric field using the geomagnetic field and ionospheric conductivity data from 1958 to 2015, and clarify the mechanism of long-term variation in the ionosphere and upper atmosphere. In the present analysis, we used geomagnetic Kp index and 1-hour geomagnetic field data archived in the database of WDC for Geomagnetism, Kyoto University. In order to investigate the solar activity dependence of the Sq ionospheric electric field, we referred to the monthly-mean solar F10.7 index. We also used two-dimensional ionospheric conductivities integrated in the height range of 85-140 km. We first selected geomagnetic field data corresponding to the solar quiet day when the Kp index is less than 4. Then, we identified the Sq variation as a deviation from the value at midnight in both the X and Y components of the selected geomagnetic field data. Finally, we obtained the Sq ionospheric electric fields by solving Ohm’s equation with the monthly-mean height-integrated ionospheric conductivity and Sq variation of geomagnetic field. As a result, the long-term variation of the Sq variation and ionospheric conductivities at Guam and Memanbetsu around the noon showed a clear seasonal variation and 11-year solar activity dependence during 1958-2015. Both the Sq variation and ionospheric conductivities tended to increase during each high solar activity. The pattern of the seasonal variation of the Sq field was different from the different component of geomagnetic field, indicating that the X component becomes maximum in March equinox while the Y-component becomes maximum in September equinox. This feature could not be seen in the seasonal variation of ionospheric conductivities. The Sq ionospheric zonal and meridional electric fields also showed a clear seasonal variation and 11-year solar activity dependence. The zonal electric field was positively correlated with the F10.7 index at Guam near the equatorial region while it was negatively correlated at Menambetsu in the middle-latitude region. This result implies that the solar activity dependence of zonal electric field is different from different latitude. In order to check if this relationship can be seen at all geomagnetic stations, we analyzed the Sq zonal electric field at 83 geomagnetic stations. As a result, the global distribution of correlation coefficient between the F10.7 index and zonal electric field with no lag showed positive and negative values in the equatorial and middle-latitude regions, respectively, without depending on the geographical longitude. Therefore, it can be concluded that the solar activity dependence of the Sq zonal electric field around the noon is globally different ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P16 - PEM03-P16 Japan Geoscience Union Meeting 2016 between the equatorial and middle-latitude regions. In future study, we investigate the solar activity dependence of the zonal electric field at all local times, and clarify a cause of the electric field depression during the high solar activity. Keywords: Geomagnetic solar quiet daily variation, Solar activity, Ionospheric electric field, Seasonal variation, Upper atmosphere, Equatorial region ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P16 - PEM03-P17 Japan Geoscience Union Meeting 2016 Coherent seasonal, annual, and quasi-biennial variations in ionospheric tidal/SPW amplitudes *Loren Chang1, Yan-Yi Sun1, Jia Yue2, Jack Chieh Wang1, Shih-Han Chien1 1.Institute of Space Science, National Central University, Jhongli, Taoyuan City, Taiwan, 2.Center for Atmospheric Science, Hampton University, Virginia, USA In this study, we examine the coherent spatial and temporal modes dominating the variation of selected ionospheric tidal and stationary planetary wave signatures from 2007 - 2013 FORMOSAT-3/COSMIC total electron content observations using Multi-dimensional Ensemble Empirical Mode Decomposition (MEEMD) from the Hilbert-Huang Transform. We examine the DW1, SW2, DE3, and SPW4 components, which are driven by a variety of in-situ and vertical coupling sources. The intrinsic mode functions (IMFs) resolved by MEEMD analysis allows for the isolation of the dominant modes of variability for prominent ionospheric tidal / SPW signatures in a manner not previously used, allowing the effects of specific drivers to be examined individually. The time scales of the individual IMFs isolated for all tidal/SPW signatures correspond to a semiannual variation at EIA latitudes maximizing at the equinoxes, as well as annual oscillations at the EIA crests and troughs. All tidal / SPW signatures show one IMF isolating an ionospheric quasi-biennial oscillation (QBO) in the equatorial latitudes maximizing around January of odd numbered years. This TEC QBO variation is in phase with a similar QBO variation isolated in both the GUVI zonal mean column O/N2 density ratio as well as the F10.7 solar radio flux index around solar maximum, while showing temporal variation more similar to that of GUVI O/N2 during the time around the 2008/2009 extended solar minimum. These results point to both quasi-biennial variations in solar irradiance as well as thermosphere / ionosphere composition as a generation mechanism for the ionospheric QBO. Keywords: Thermosphere, Ionosphere, Tides, QBO ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P17 - PEM03-P18 Japan Geoscience Union Meeting 2016 The ionospheric characteristics over the northern equatorial anomaly crest during the prolonged solar minimum period *Yu-Jung Chuo1 1.Department of Information Technology, Ling Tung University In this study we have analyzed the diurnal, monthly, seasonal, and annual variation in NmF2, hmF2, foE, B0, scale height at F2 layer peak height (Hm), total electron content (TEC), and ionospheric equivalent slab thickness (tau symbol) over the northern crest equatorial anomaly area at solar minimum during 1995-1996 and 2008-2009. We collected the data from an ionosode station located at Chung-Li Observation (121.1.oE, 25.0oN) and GPS receiver (TWTF) located at Tao-Yuan (121.09oE, 24.57oN). The result shows the first maximum value for NmF2 and TEC occurred a time delay in 2008 comparison with values in 1995. The result of foE depicts a lower value during 2008-2009 than variation in 1995-1996. The variation of hmF2 in 2008-2009 was lower than values in 1995-1996. The ionospheric equivalent slab thickness during 0600-1200 LT was higher in 2008-2009 than values in 1995-1996, particularly in summer season. Furthermore, a comprehensive discussion of the physics processes for the variation of ionosphere during the prolonged low solar activity period. Keywords: ionospheric physics, solar activity, ionospheric dynamics ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P18 - PEM03-P19 Japan Geoscience Union Meeting 2016 D-region ionospheric disturbances after the 2011 off the Pacific coast of Tohoku Earthquake using LF transmitter signals *Hiroyo Ohya1, Yuta Takishita2, Fuminori Tsuchiya3, Hiroyuki Nakata1, Kazuo Shiokawa4, Yoshizumi Miyoshi4, Takahiro Obara3, Hiroaki Misawa3 1.Graduate School of Engineering, Chiba University, 2.Faculty of Engineering, Chiba University, 3.PPARC, Graduate School of Science, Tohoku University, 4.Institute for Space-Earth Environmental Research, Nagoya University So far, a lot of studies for the F-region ionosphere associated with earthquakes have been reported, although few studies for the D-region ionosphere have reported. It is difficult to observe the D-region electron density because of high collision frequency between plasma and the neutral atmosphere. In this study, we investigate the D-region disturbances associated with the 2011 off the Pacific coast of Tohoku Earthquake using intensity and phase of LF transmitter signals. The phase was converted to reflection height based on Earth-ionosphere waveguide mode theory. The reflection height corresponds to electron density in the D-region. The propagation paths are Saga-Rikubetsu (RKB) and BPC(China)-RKB. As a result, clear oscillations of the intensity over both propagation paths were simultaneously observed about 6 minutes and 12 seconds after the earthquake onset. The both periods of the intensity and reflection height oscillations were about 100 s. The one-to-one corresponding between the intensity and reflection height was not seen clearly. The changes of the intensity and reflection height for the oscillations were about 0.1 dB and 50 - 65 m, respectively. The time difference between the earthquake onset and the oscillations was consistent with the propagation time of the Rayleigh waves (seismic waves) propagating from the epicenter to the LF propagation paths along the Earth surface, plus the propagation time of acoustic waves propagating from the ground to 70 km altitude vertically. Thus, the LF oscillations may be caused by the acoustic waves excited by the Rayleigh waves. ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P19 - PEM03-P20 Japan Geoscience Union Meeting 2016 The photochemical model of atomic oxygen ions retrieving from ground-based observation of airglow *Yi Duann1, Yi Chung Chiou1, Loren C. Chang1 1.National Central University To study the chemistry and composition of the upper atmosphere, we can utilize airglow emissions from the photochemical reactions of the ions in this region. When the atomic oxygen ions, which are distributed in the ionospheric F region, experience an energy level transition, visible light with a wavelength of 630 nm is released. We used the photometer system built by our team to perform ground-based observations of airglow over the sky of Taiwan at The Lulin Observatory (23°28′07″N, 120°52′25″E) during nighttime. We combined the mean values of our observations every 10 minutes with a photo chemistry model based on the formula derived from the theory of R. Link and L. L. Cogger. With this method, we can estimate how the density of oxygen atomic ions varies with time and altitude. This system will be used for long term observations to study the seasonal variation of upper atmosphere composition. Keywords: photochemical, airglow, ionosphere ©2016. Japan Geoscience Union. All Right Reserved. - PEM03-P20 -

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