The Tibetan Plateau and nearby surrounding area (the Third Pole area) dramatically impacts the wo... more The Tibetan Plateau and nearby surrounding area (the Third Pole area) dramatically impacts the world’s environment and especially controls climatic and environmental changes in China, Asia and even in the Northern Hemisphere. Supported by the Chinese Academy of Sciences (CAS) and some international organizations, the Third Pole Environment (TPE) Programme is now under way. First, the background of the establishment of the TPE, the establishment and monitoring plans on long-term for the TPE and six comprehensive observation and study stations are introduced. Then the preliminary observational analysis results on atmosphere−land interaction are presented. The study on the regional distribution of land surface heat fluxes is of paramount importance over the heterogeneous landscape of the Third Pole area. A parameterization methodology based on satellite and in situ data is described and tested for deriving the regional surface heat fluxes (net radiation flux, soil heat flux, sensible h...
The Tibetan Plateau (TP) has become a focus of strong scientific interest due to its role in the ... more The Tibetan Plateau (TP) has become a focus of strong scientific interest due to its role in the global water cycle and its reaction to climate change. Regional flux estimates of sensible and latent heat are important variables for linking the energy and hydrological cycles at the TP’s surface. Within this framework, a 3-year dataset (2008–2010) of eddy covariance measured turbulent fluxes was compiled from four stations on the TP into a standardised workflow: corrections and quality tests were applied using an internationally comparable software package. Second, the energy balance closure (CEB) was determined and two different closure corrections applied. The four stations (Qomolangma, Linzhi, NamCo and Nagqu) represent different locations and typical land surface types on the TP (high altitude alpine steppe with sparse vegetation, a densely vegetated alpine meadow, and bare soil/gravel, respectively). We show that the CEB differs between each surface and undergoes seasonal changes...
Quarterly Journal of the Royal Meteorological Society, 2014
ABSTRACT Wind profile data were measured by a wind profiler at QOMS (The Qomolangma Station for A... more ABSTRACT Wind profile data were measured by a wind profiler at QOMS (The Qomolangma Station for Atmospheric Environmental Observation and Research, Chinese Academy of Sciences) and in, separate experiments, GPS radiosondes were used at Shiquanhe Station and Litang Station on the Tibetan Plateau (TP). All three stations are located in the most rugged areas of the TP. QOMS is surrounded by the Himalaya, Shiquanhe Station by the Transhimalaya and Litang station is near the Hengduan Mountains. Using observational wind profile data, effective aerodynamic roughness length and zero-plane displacement height d0 are determined using the neutral logarithmic wind profile law. The results show that the values of derived from the wind profiles can be considerably larger than the small-scale aerodynamic roughness lengths of the land surface around the three stations. Subsequently, several parameterization schemes which use land surface characteristics to estimate and d0, such as roughness obstacle height and density, were assessed. The result indicates that of all the methods available, that proposed by Grant and Mason, where the drag coefficient D=0.5, gives the best estimate of . The interim European Center for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset underestimates effective aerodynamic roughness length in mountainous areas of the TP due to its use of a smaller drag coefficient of D=0.4. For estimating d0, the method of Kutzbach performs well when the density of roughness obstacles (λ) is low, whereas the method of Raupach et al gives a more reliable estimate when λ is high. Although this analysis has some limitations, it can feasibly account for form drag being exerted by an unresolved topography in the mountainous areas of the TP.
ABSTRACT The REFLEX 2012 campaign was initiated as part of a training course on the organization ... more ABSTRACT The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.
In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was meas... more In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was measured during a regional radiosonde observation campaign in 2008 and found to be deeper than indicated by previously measurements. Results indicate that during fair weather conditions on winter days, the top of the mixed layers can be up to 5 km above the ground (9.4 km above sea level). Measurements also show that the depth of the ABL is quite distinct for three different periods (winter, monsoon-onset, and monsoon seasons). Turbulence at the top of a deep mixing layer can rise up to the upper troposphere. As a consequence, as confirmed by trajectory analysis, interaction occurs between deep ABLs and the low tropopause during winter over the Tibetan Plateau.
The Tibetan Plateau and nearby surrounding area (the Third Pole area) dramatically impacts the wo... more The Tibetan Plateau and nearby surrounding area (the Third Pole area) dramatically impacts the world’s environment and especially controls climatic and environmental changes in China, Asia and even in the Northern Hemisphere. Supported by the Chinese Academy of Sciences (CAS) and some international organizations, the Third Pole Environment (TPE) Programme is now under way. First, the background of the establishment of the TPE, the establishment and monitoring plans on long-term for the TPE and six comprehensive observation and study stations are introduced. Then the preliminary observational analysis results on atmosphere−land interaction are presented. The study on the regional distribution of land surface heat fluxes is of paramount importance over the heterogeneous landscape of the Third Pole area. A parameterization methodology based on satellite and in situ data is described and tested for deriving the regional surface heat fluxes (net radiation flux, soil heat flux, sensible h...
The Tibetan Plateau (TP) has become a focus of strong scientific interest due to its role in the ... more The Tibetan Plateau (TP) has become a focus of strong scientific interest due to its role in the global water cycle and its reaction to climate change. Regional flux estimates of sensible and latent heat are important variables for linking the energy and hydrological cycles at the TP’s surface. Within this framework, a 3-year dataset (2008–2010) of eddy covariance measured turbulent fluxes was compiled from four stations on the TP into a standardised workflow: corrections and quality tests were applied using an internationally comparable software package. Second, the energy balance closure (CEB) was determined and two different closure corrections applied. The four stations (Qomolangma, Linzhi, NamCo and Nagqu) represent different locations and typical land surface types on the TP (high altitude alpine steppe with sparse vegetation, a densely vegetated alpine meadow, and bare soil/gravel, respectively). We show that the CEB differs between each surface and undergoes seasonal changes...
Quarterly Journal of the Royal Meteorological Society, 2014
ABSTRACT Wind profile data were measured by a wind profiler at QOMS (The Qomolangma Station for A... more ABSTRACT Wind profile data were measured by a wind profiler at QOMS (The Qomolangma Station for Atmospheric Environmental Observation and Research, Chinese Academy of Sciences) and in, separate experiments, GPS radiosondes were used at Shiquanhe Station and Litang Station on the Tibetan Plateau (TP). All three stations are located in the most rugged areas of the TP. QOMS is surrounded by the Himalaya, Shiquanhe Station by the Transhimalaya and Litang station is near the Hengduan Mountains. Using observational wind profile data, effective aerodynamic roughness length and zero-plane displacement height d0 are determined using the neutral logarithmic wind profile law. The results show that the values of derived from the wind profiles can be considerably larger than the small-scale aerodynamic roughness lengths of the land surface around the three stations. Subsequently, several parameterization schemes which use land surface characteristics to estimate and d0, such as roughness obstacle height and density, were assessed. The result indicates that of all the methods available, that proposed by Grant and Mason, where the drag coefficient D=0.5, gives the best estimate of . The interim European Center for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) dataset underestimates effective aerodynamic roughness length in mountainous areas of the TP due to its use of a smaller drag coefficient of D=0.4. For estimating d0, the method of Kutzbach performs well when the density of roughness obstacles (λ) is low, whereas the method of Raupach et al gives a more reliable estimate when λ is high. Although this analysis has some limitations, it can feasibly account for form drag being exerted by an unresolved topography in the mountainous areas of the TP.
ABSTRACT The REFLEX 2012 campaign was initiated as part of a training course on the organization ... more ABSTRACT The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.
In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was meas... more In this study the depth of the atmospheric boundary layer (ABL) over the Tibetan Plateau was measured during a regional radiosonde observation campaign in 2008 and found to be deeper than indicated by previously measurements. Results indicate that during fair weather conditions on winter days, the top of the mixed layers can be up to 5 km above the ground (9.4 km above sea level). Measurements also show that the depth of the ABL is quite distinct for three different periods (winter, monsoon-onset, and monsoon seasons). Turbulence at the top of a deep mixing layer can rise up to the upper troposphere. As a consequence, as confirmed by trajectory analysis, interaction occurs between deep ABLs and the low tropopause during winter over the Tibetan Plateau.
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