Atmosphere

17 pages, 3420 KiB

Open AccessArticle

Occurrence and Coupling of Heat and Ozone Events and Their Relation to Mortality Rates in Berlin, Germany, between 2000 and 2014

by Alexander Krug, Daniel Fenner, Achim Holtmann and Dieter Scherer

Atmosphere 2019, 10(6), 348; https://doi.org/10.3390/atmos10060348 - 25 Jun 2019

Cited by 14 | Viewed by 4719

Abstract

Episodes of hot weather and poor air quality pose significant consequences for public health. In this study, these episodes are addressed by applying the observational data of daily air temperature and ozone concentrations in an event-based risk assessment approach in order to detect [...] Read more.

Episodes of hot weather and poor air quality pose significant consequences for public health. In this study, these episodes are addressed by applying the observational data of daily air temperature and ozone concentrations in an event-based risk assessment approach in order to detect individual heat and ozone events, as well as events of their co-occurrence in Berlin, Germany, in the years 2000 to 2014. Various threshold values are explored so as to identify these events and to search for the appropriate regressions between the threshold exceedances and mortality rates. The events are further analyzed in terms of their event-specific mortality rates and their temporal occurrences. The results reveal that at least 40% of all heat events during the study period are accompanied by increased ozone concentrations in Berlin, particularly the most intense and longest heat events. While ozone events alone are only weakly associated with increased mortality rates, elevated ozone concentrations during heat events are found to amplify mortality rates. We conclude that elevated air temperatures during heat events are one major driver for increased mortality rates in Berlin, but simultaneously occurring elevated ozone concentrations act as an additional stressor, leading to an increased risk for the regional population. Full article

(This article belongs to the Section Biometeorology and Bioclimatology)

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Study area and locations of observation sites of air temperature (Tempelhof) and ozone concentrations (Wedding, urban station #1; Neukölln, urban station #2; Marienfelde, suburban station #1; Grunewald, suburban station #2; Buch, suburban station #3; Friedrichshagen, suburban station #4; and Frohnau, suburban station #5) in Berlin. Land cover based on CORINE 2012, v18.5. The black line marks the administrative border of the city. Full article ">Figure 2
Schematic overview of possible threshold (Thr) exceedances (top row). The resulting heat events (HE) and ozone events (OE) are labeled. The classified event types that were used in the analyses were defined as single heat events (HEs), single ozone events (OEs), coupled heat events (HEc), and coupled ozone events (OEc). Full article ">Figure 3
Regressions between the mean mortality rates (MR; y-axis) during HE from 2000 to 2014 in Berlin, and event magnitudes (x-axis) for selected thresholds values. (a) Tmean > 20 °C (five lag days); (b) Tmean > 22 °C (four lag days); (c) Tmean > 24 °C (six lag days). Full article ">Figure 4
Comparison of the explained variance (r2) for all of the statistically highly significant (p < 0.01) regression models and for different ozone observation sites. The x-axis displays the model-specific threshold values. Full article ">Figure 5
Regressions between mean mortality rates (MRs; y-axis) during OE from 2000 to 2014 in Berlin, and event magnitudes (x-axis) for selected thresholds, based on observations at site Wedding (urban station #1). (a) Maximum daily eight-hourly average ozone concentration (MDA8) > 90 µg m−3 (zero lag days); (b) MDA8 > 100 µg m−3 (zero lag days); (c) MDA8 > 105 µg m−3 (one lag day). Full article ">Figure 6
Comparison of HEs (yellow bars) and HEc (purple bars) with Tmean as the predictor variable (x-axis) for daily mortality rates (y-axis) for different threshold combinations ((a) Tmean > 20 °C, MDA8 >90 µg m−3; (b) Tmean > 20 °C, MDA8 > 100 µg m−3; (c) Tmean > 20 °C, MDA8 > 105 µg m−3; (d) Tmean > 22 °C, MDA8 > 90 µg m−3; (e) Tmean > 22 °C, MDA8 > 100 µg m−3; (f) Tmean > 22 °C, MDA8 > 105 µg m−3; (g) Tmean > 24 °C, MDA8 > 90 µg m−3; (h) Tmean > 24 °C, MDA8 > 100 µg m−3; (i) Tmean > 24 °C, MDA8 > 105 µg m−3). Separate regression lines (based on individual events) for HEs and HEc are shown if significant (p < 0.05). Events are grouped into classes of similar event magnitudes (boxes, top x-axis). The edges of each box reflect the 25th and 75th percentile, median values are given as solid lines, and whiskers are the minimum and maximum values, respectively. Less than five events per class are shown as dots. The number of events (n) is displayed above each box. Significant different means (Mann–Whitney U-test) between HEs and HEc are signed at p < 0.05 per class for n ≥ 5; n. s. denotes not significant differences. Full article ">Figure 7
Comparison of OEs (green bars) and OEc (purple bars) with MDA8 as a predictor variable (x-axis) for the daily mortality rates (y-axis) for different threshold combinations ((a) Tmean > 20 °C, MDA8 > 90 µg m−3; (b) Tmean > 20 °C, MDA8 > 100 µg m−3; (c) Tmean > 20 °C, MDA8 > 105 µg m−3; (d) Tmean > 22 °C, MDA8 > 90 µg m−3; (e) Tmean > 22 °C, MDA8 > 100 µg m−3; (f) Tmean > 22 °C, MDA8 > 105 µg m−3; (g) Tmean > 24 °C, MDA8 > 90 µg m−3; (h) Tmean > 24 °C, MDA8 > 100 µg m−3; (i) Tmean > 24 °C, MDA8 > 105 µg m−3). Separate regression lines (based on individual events) for OEs and OEc are shown if significant (p < 0.05). Events are grouped into classes of similar event magnitudes (boxes, top x-axis). The edges of each box reflect the 25th and 75th percentile, median values are given as solid lines, and whiskers are the minimum and maximum values, respectively. Less than five events per class are shown as dots. The number of events (n) is displayed above each box. Significant different means (Mann–Whitney U-test) between OEs and OEc are signed as p < 0.05 per class for n ≥ 5; n. s. denotes not significant differences. Full article ">Figure 8
Temporal occurrences of HEs (Tmean > 22 °C, orange), OEs (MDA8 > 100 µg m−3, green), and corresponding coupled events (HEc/OEc, purple) in Berlin from 2000 to 2014. Overlapping days of HEs and OEs that are not classified as coupled events are marked in olive-green. Full article ">Figure 9
Stacked bars for the number of events per length of HEs (Tmean > 22 °C, orange), OEs (MDA8 > 100 µg m−3, green), and corresponding coupled events (HEc/OEc, purple) in Berlin from 2000 to 2014. Full article ">

25 pages, 967 KiB

Open AccessArticle

Accurate Characterization of Land Cover in Urban Environments: Determining the Importance of Including Obscured Impervious Surfaces in Urban Heat Island Models

by Paul Coseo and Larissa Larsen

Atmosphere 2019, 10(6), 347; https://doi.org/10.3390/atmos10060347 - 25 Jun 2019

Cited by 19 | Viewed by 3845

Abstract

Urban heat islands (UHI) increase summer temperatures and can threaten human well-being during extreme heat events. Since urbanization plays a key role in UHI development, accurate quantification of land cover types is critical to their identification. This study examines how quantifying land cover [...] Read more.

Urban heat islands (UHI) increase summer temperatures and can threaten human well-being during extreme heat events. Since urbanization plays a key role in UHI development, accurate quantification of land cover types is critical to their identification. This study examines how quantifying land cover types using both two- and three-dimensional approaches to land cover quantification affects an UHI model’s explanatory power. Two-dimensional approaches treat tree canopies as a land cover, whereas three-dimensional approaches document the land cover areas obscured under tree canopies. We compare how accurately the two approaches explain elevated air temperatures in Chicago, Illinois. Our results show on average 14.1% of impervious surface areas went undocumented using a two-dimensional approach. The most common concealed impervious surfaces were sidewalks, driveways, and parking lots (+6.2%), followed by roads (+6.1%). Yet, the three-dimensional approach did not improve the explanatory power of a UHI model substantially. At 2 a.m., the adjusted R² increased from 0.64 for a two-dimensional analysis to 0.68 for a three-dimensional analysis. We found that the less time consuming two-dimensional quantification of land covers was sufficient to predict neighborhood UHIs. As climate change exacerbates UHI, more cities will map urban hotspots and this research increases our understanding of alternative approaches. Full article

(This article belongs to the Special Issue Effects of Urban Areas on Climate Change Conditions)

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17 pages, 7803 KiB

Open AccessArticle

Assessing the Potential Highest Storm Tide Hazard in Taiwan Based on 40-Year Historical Typhoon Surge Hindcasting

by Yi-Chiang Yu, Hongey Chen, Hung-Ju Shih, Chih-Hsin Chang, Shih-Chun Hsiao, Wei-Bo Chen, Yung-Ming Chen, Wen-Ray Su and Lee-Yaw Lin

Atmosphere 2019, 10(6), 346; https://doi.org/10.3390/atmos10060346 - 25 Jun 2019

Cited by 35 | Viewed by 5167

Abstract

Typhoon-induced storm surges are catastrophic disasters in coastal areas worldwide, although typhoon surges are not extremely high in Taiwan. However, the rising water level around an estuary could be a block that obstructs the flow of water away from the estuary and indirectly [...] Read more.

Typhoon-induced storm surges are catastrophic disasters in coastal areas worldwide, although typhoon surges are not extremely high in Taiwan. However, the rising water level around an estuary could be a block that obstructs the flow of water away from the estuary and indirectly forms an overflow in the middle or lower reaches of a river if the occurrence of the highest storm surge (HSS) coincides with the highest astronomical tide (HAT). Therefore, assessing the highest storm tide (HST, a combination of the HSS and HAT) hazard level along the coast of Taiwan is particularly important to an early warning of riverine inundation. This study hindcasted the storm surges of 122 historical typhoon events from 1979 to 2018 using a high-resolution, unstructured-grid, surge-wave fully coupled model and a hybrid typhoon wind model. The long-term recording measurements at 28 tide-measuring stations around Taiwan were used to analyze the HAT characteristics. The hindcasted HSSs of each typhoon category (the Central Weather Bureau of Taiwan classified typhoon events into nine categories according to the typhoon’s track) were extracted and superposed on the HATs to produce the individual potential HST hazard maps. Each map was classified into six hazard levels (I to VI). Finally, a comprehensive potential HST hazard map was created based on the superposition of the HSSs from 122 typhoon events and HATs. Full article

(This article belongs to the Special Issue Storm Surge Modeling – Capturing the Wind)

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17 pages, 4155 KiB

Open AccessArticle

Transport Pathways and Potential Source Regions of PM_2.5 on the West Coast of Bohai Bay during 2009–2018

by Tianyi Hao, Ziying Cai, Shucheng Chen, Suqin Han, Qing Yao and Wenyan Fan

Atmosphere 2019, 10(6), 345; https://doi.org/10.3390/atmos10060345 - 25 Jun 2019

Cited by 26 | Viewed by 3897

Abstract

Mass concentration data for particulate matter with an aerodynamic diameter less than or equal to 2.50 μm (PM_2.5) combined with backward trajectory cluster analysis, potential source contribution function (PSCF), and concentration weighted trajectory (CWT) methods were used to investigate the transport [...] Read more.

Mass concentration data for particulate matter with an aerodynamic diameter less than or equal to 2.50 μm (PM_2.5) combined with backward trajectory cluster analysis, potential source contribution function (PSCF), and concentration weighted trajectory (CWT) methods were used to investigate the transport pathways and potential source regions of PM_2.5 on the west coast of Bohai Bay from 2009 to 2018. Two pathways responsible for the transportation of high PM_2.5 levels were identified, namely a southerly pathway and a northwesterly pathway. The southerly pathway represented the major transport pathway of PM_2.5 for all seasons. As a regional transport pathway, it had the greatest impact in winter, followed by autumn. The southerly transport pathway passed over the Shandong and Hebei provinces before reaching Tianjin: Air masses were transported within the boundary layer (below 925 hPa), representing a slow-moving air flow. The northwesterly pathway mostly occurred in winter and autumn and passed over desert and semidesert regions in Outer Mongolia, the sand lands of Inner Mongolia, and Hebei. The air masses associated with the northwesterly pathway represented fast-moving airflows responsible for long-range transportation of PM_2.5. Two potential source regions that contributed to high PM_2.5 loadings on the west coast of Bohai Bay were identified, “southerly source regions” and “northwesterly source regions”. The southerly source regions, with weighted CWT (WCWT) values in winter greater than 140.00 μg/m³, were anthropogenic source regions, including southern Hebei, western Shandong, eastern Henan, northern Anhui, and northern Jiangsu. The northwesterly source regions, with WCWT values in winter of 80.00–140.00 μg/m³, were natural source regions, encompassing central Inner Mongolia and southern Mongolia. In addition, the southerly transport pathway passed though anthropogenic source regions, while the northwesterly transport pathway passed though natural source regions. The impacts of anthropogenic source regions on PM_2.5 loadings on the west coast of Bohai Bay were greater than those of natural source regions. Full article

(This article belongs to the Section Air Quality)

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25 pages, 9844 KiB

Open AccessArticle

Development and Evaluation of a WRF-Based Mesoscale Numerical Weather Prediction System in Northwestern China

by Tiejun Zhang, Yaohui Li, Haixia Duan, Yuanpu Liu, Dingwen Zeng, Cailing Zhao, Chongshui Gong, Ganlin Zhou, Linlin Song and Pengcheng Yan

Atmosphere 2019, 10(6), 344; https://doi.org/10.3390/atmos10060344 - 25 Jun 2019

Cited by 7 | Viewed by 5041

Abstract

Based on the U.S. Weather Research and Forecasting (WRF) numerical model, this study has developed the Northwest Mesoscale Numerical Prediction Service and Experimental System (NW-MNPS). Surface and sounding data assimilation has been introduced for this system. Effects of model vertical layers and land-use [...] Read more.

Based on the U.S. Weather Research and Forecasting (WRF) numerical model, this study has developed the Northwest Mesoscale Numerical Prediction Service and Experimental System (NW-MNPS). Surface and sounding data assimilation has been introduced for this system. Effects of model vertical layers and land-use data replacement have been assessed. A year-long forecast validation and analysis have been performed. The following results have been obtained: (1) Data assimilation can improve the performance of regional numerical forecasting. (2) Compared to simulations with 40 vertical layers, simulations with 55 vertical layers are more accurate. The average absolute error and root-mean-square error of the 48 h surface element forecast decrease. The analysis of threat score (TS) and equitable threat score (ETS) shows that there are higher TS and ETS values for various precipitation intense levels, in particular for heavy rainfall when comparing a 55-vertical-layer test with a 40-vertical-layer test. (3) Updating the database to include vegetation coverage can more accurately reflect actual surface conditions. The updated land-use data reduce prediction errors in all domains of the NW-MNPS. Full article

(This article belongs to the Section Meteorology)

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20 pages, 4996 KiB

Open AccessArticle

The Linkage of the Precipitation in the Selenga River Basin to Midsummer Atmospheric Blocking

by Olga Yu. Antokhina, Pavel N. Antokhin, Yuliya V. Martynova and Vladimir I. Mordvinov

Atmosphere 2019, 10(6), 343; https://doi.org/10.3390/atmos10060343 - 24 Jun 2019

Cited by 6 | Viewed by 3625

Abstract

The linkage between atmospheric blocking (blocking frequency, BF) and total monthly July precipitation in the Selenga River Basin, the main tributary of Lake Baikal, for the period 1979–2016 was investigated. Based on empirical orthogonal functions (EOF) analysis, two dominant modes of precipitation over [...] Read more.

The linkage between atmospheric blocking (blocking frequency, BF) and total monthly July precipitation in the Selenga River Basin, the main tributary of Lake Baikal, for the period 1979–2016 was investigated. Based on empirical orthogonal functions (EOF) analysis, two dominant modes of precipitation over the Selenga River Basin were extracted. The first EOF mode (EOF 1) is related to precipitation fluctuations mainly in the Mongolian part of Selenga; the second EOF mode (EOF 2)—in the Russian part of Selenga. Based on two different modes obtained, the total amount of precipitation individually for the Russian and Mongolian part of Selenga was calculated. Correlation analysis has demonstrated that precipitation over the Mongolian part of the Selenga Basin is positively correlated to blocking over Eastern Siberia/Mongolia (80–120° E, ESM-BF). Precipitation over the Russian part of the Selenga Basin is positively correlated to blocking over the Urals-Western Siberia (50–80° E, UWS-BF) and European blocking (0–50° E, E-BF). However, the linkage is not stable, and after the mid-1990s, the obtained positive correlation became insignificant. The analysis has shown that the dominance of E or ESM-blocking in July was the primary driver of the existence of two precipitation modes over the Selenga River Basin. During 1996–2016, the negative trend of time coefficients of EOF 1 and 2 for precipitation in Selenga had been observed, which was characterized by displacement of positive precipitation anomalies outside the basin. At the same time, there was a weakening of the linkage between precipitation in the Selenga Basin and blocking frequency. We have revealed two wave-like modes over Northern Eurasia and the subtropical part of Eurasia corresponding to E, ESM-blocks in 1979–1995 and 1996–2016. The change of the Northern and subtropical wave modes is one of the causes for the weakening of the linkage between atmospheric blocking and precipitation in the Selenga Basin and as a consequence decreased precipitation in the Russian and Mongolian part of Selenga during 1979–2016. Full article

(This article belongs to the Special Issue Atmospheric and Ocean Optics: Atmospheric Physics)

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12 pages, 4715 KiB

Open AccessArticle

Broad-Band Transmission Characteristics of Polarizations in Foggy Environments

by Tianwei Hu, Fei Shen, Kaipeng Wang, Kai Guo, Xiao Liu, Feng Wang, Zhiyong Peng, Yuemeng Cui, Rui Sun, Zhizhong Ding, Jun Gao and Zhongyi Guo

Atmosphere 2019, 10(6), 342; https://doi.org/10.3390/atmos10060342 - 24 Jun 2019

Cited by 23 | Viewed by 3912

Abstract

Based on the Monte Carlo (MC) algorithm, we simulate the evolutions of different types of the polarized lights in the broad-band range from visible to infrared in foggy environments. Here, we have constructed two scattering systems to simulate the transmission characteristics of the [...] Read more.

Based on the Monte Carlo (MC) algorithm, we simulate the evolutions of different types of the polarized lights in the broad-band range from visible to infrared in foggy environments. Here, we have constructed two scattering systems to simulate the transmission characteristics of the polarized lights: (1) A monodisperse system based on five types of particles with the sizes of 0.5, 1.0, 2.5, 4, and 5 µm, respectively; (2) a polydisperse system based on scattering particles with a mean value (size) of 2.0 μm. Our simulation results show that linearly polarized light (LPL) and circularly polarized light (CPL) exhibit different advantages in different wavelengths and different scattering systems. The polarization maintenances (PM) of the degree of circular polarizations (DoCPs) are better than those of the degree of linear polarizations (DoLPs) for most incident wavelengths. CPL is not superior to LPL in the strong-absorption wavelengths of 3.0µm, 6.0µm, and long infrared. Here, when the wavelength is closer to the particle sizes in a system, the influence on propagating polarizations will be more obvious. However, the difference in the degree of polarization (DoP) between the resulting CPL and LPL is positive at these points, which means the penetrating ability of CPL is superior to that of LPL in these scattering systems. We have also simulated the extinction efficiency Q_ext and the scattering index ratio Q_ratio as functions of both wavelength and particle size for analyzing polarization’s transmission characteristics. Our work paves the way of selecting the optimal incident wavelengths and polarizations for concrete scattering systems. Full article

(This article belongs to the Section Aerosols)

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20 pages, 5029 KiB

Open AccessArticle

Using eXtreme Gradient BOOSTing to Predict Changes in Tropical Cyclone Intensity over the Western North Pacific

by Qingwen Jin, Xiangtao Fan, Jian Liu, Zhuxin Xue and Hongdeng Jian

Atmosphere 2019, 10(6), 341; https://doi.org/10.3390/atmos10060341 - 22 Jun 2019

Cited by 20 | Viewed by 3847

Abstract

Coastal cities in China are frequently hit by tropical cyclones (TCs), which result in tremendous loss of life and property. Even though the capability of numerical weather prediction models to forecast and track TCs has considerably improved in recent years, forecasting the intensity [...] Read more.

Coastal cities in China are frequently hit by tropical cyclones (TCs), which result in tremendous loss of life and property. Even though the capability of numerical weather prediction models to forecast and track TCs has considerably improved in recent years, forecasting the intensity of a TC is still very difficult; thus, it is necessary to improve the accuracy of TC intensity prediction. To this end, we established a series of predictors using the Best Track TC dataset to predict the intensity of TCs in the Western North Pacific with an eXtreme Gradient BOOSTing (XGBOOST) model. The climatology and persistence factors, environmental factors, brainstorm features, intensity categories, and TC months are considered inputs for the models while the output is the TC intensity. The performance of the XGBOOST model was tested for very strong TCs such as Hato (2017), Rammasum (2014), Mujiage (2015), and Hagupit (2014). The results obtained show that the combination of inputs chosen were the optimal predictors for TC intensification with lead times of 6, 12, 18, and 24 h. Furthermore, the mean absolute error (MAE) of the XGBOOST model was much smaller than the MAEs of a back propagation neural network (BPNN) used to predict TC intensity. The MAEs of the forecasts with 6, 12, 18, and 24 h lead times for the test samples used were 1.61, 2.44, 3.10, and 3.70 m/s, respectively, for the XGBOOST model. The results indicate that the XGBOOST model developed in this study can be used to improve TC intensity forecast accuracy and can be considered a better alternative to conventional operational forecast models for TC intensity prediction. Full article

(This article belongs to the Section Meteorology)

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21 pages, 7088 KiB

Open AccessArticle

Spatiotemporal Variability of Actual Evapotranspiration and the Dominant Climatic Factors in the Pearl River Basin, China

by Weizhi Gao, Zhaoli Wang and Guoru Huang

Atmosphere 2019, 10(6), 340; https://doi.org/10.3390/atmos10060340 - 22 Jun 2019

Cited by 9 | Viewed by 3184

Abstract

Evapotranspiration is a vital component of the land surface process, thus, a more accurate estimate of evapotranspiration is of great significance to agricultural production, research on climate change, and other activities. In order to explore the spatiotemporal variation of evapotranspiration under global climate [...] Read more.

Evapotranspiration is a vital component of the land surface process, thus, a more accurate estimate of evapotranspiration is of great significance to agricultural production, research on climate change, and other activities. In order to explore the spatiotemporal variation of evapotranspiration under global climate change in the Pearl River Basin (PRB), in China, this study conducted a simulation of actual evapotranspiration (ETa) during 1960–2014 based on the variable infiltration capacity (VIC) model with a high spatial resolution of 0.05°. The nonparametric Mann–Kendall (M–K) test and partial correlation analysis were used to examine the trends of ETa. The dominant climatic factors impacting on ETa were also examined. The results reveal that the annual ETa across the whole basin exhibited a slight but not significant increasing trend during the 1960–2014 period, whereas a significant decreasing trend was found during the 1960–1992 period. At the seasonal scale, the ETa showed a significant upward trend in summer and a significant downward trend in autumn. At the spatial scale, the ETa generally showed a decreasing, but not significant, trend in the middle and upper stream of the PRB, while in the downstream areas, especially in the Pearl River Delta and Dongjiang River Basin, it exhibited a significant increasing trend. The variation of the ETa was mainly associated with sunshine hours and average air pressure. The negative trend of the ETa in the PRB before 1992 may be due to the significant decrease in sunshine hours, while the increasing trend of the ETa after 1992 may be due to the recovery of sunshine hours and the significant decrease of air pressure. Additionally, we found that the “paradox” phenomenon detected by ETa mainly existed in the middle-upper area of the PRB during the period of 1960–1992. Full article

(This article belongs to the Special Issue Evapotranspiration Observation and Prediction: Uncertainty Analysis)

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Figure 1
General location of the Pearl River Basin and the sub-regions. Notes: 1: Nanpan River; 2: Beipan River; 3: Hongshui River; 4: Liujiang River; 5: Youjiang River; 6: Zuojiang River and the main stream of the Yujiang River; 7: Hegui River; 8: Qianxun River and Xijiang River; 9: Upstream of the Dakengkou sub-region in the Beijiang River; 10: Downstream of the Dakengkou sub-region in the Beijiang River; 11: Upstream of the Qiujiangkou sub-region in the Dongjiang River; 12: Downstream of the Qiujiangkou sub-region in the Dongjiang River; 13: Pearl River Delta. Full article ">Figure 2
Calibration and validation results of the VIC model. Full article ">Figure 3
Annual ETa of the Pearl River Basin during 1960–2014 (α = 0.05). Full article ">Figure 4
Distribution of the annual average ETa in the Pearl River Basin during 1960–2014. The name of the sub-regions refer to those in <a href="#atmosphere-10-00340-f001" class="html-fig">Figure 1</a>. Full article ">Figure 5
The M–K test results of the annual ETa during 1960–2014 in the Pearl River Basin. UF represents the statistics of forward sequence, UB the statistics of backward sequence. Full article ">Figure 6
Spatial distribution of the trends of the annual ETa identified by the M–K test. (a) M–K values; (b) Change rate of the ETa. The name of the sub-regions refers to those in <a href="#atmosphere-10-00340-f001" class="html-fig">Figure 1</a>. Full article ">Figure 7
Variation trends (α = 0.05) of the ten climatic factors in the Pearl River Basin. Full article ">

14 pages, 3776 KiB

Open AccessArticle

Hurricane Boundary Layer Height Relative to Storm Motion from GPS Dropsonde Composites

by Yifang Ren, Jun A. Zhang, Stephen R. Guimond and Xiang Wang

Atmosphere 2019, 10(6), 339; https://doi.org/10.3390/atmos10060339 - 21 Jun 2019

Cited by 14 | Viewed by 4176

Abstract

This study investigates the asymmetric distribution of hurricane boundary layer height scales in a storm-motion-relative framework using global positioning system (GPS) dropsonde observations. Data from a total of 1916 dropsondes collected within four times the radius of maximum wind speed of 37 named [...] Read more.

This study investigates the asymmetric distribution of hurricane boundary layer height scales in a storm-motion-relative framework using global positioning system (GPS) dropsonde observations. Data from a total of 1916 dropsondes collected within four times the radius of maximum wind speed of 37 named hurricanes over the Atlantic basin from 1998 to 2015 are analyzed in the composite framework. Motion-relative quadrant mean composite analyses show that both the kinematic and thermodynamic boundary layer height scales tend to increase with increasing radius in all four motion-relative quadrants. It is also found that the thermodynamic mixed layer depth and height of maximum tangential wind speed are within the inflow layer in all motion-relative quadrants. The inflow layer depth and height of the maximum tangential wind are both found to be deeper in the two front quadrants, and they are largest in the right-front quadrant. The difference in the thermodynamic mixed layer depth between the front and back quadrants is smaller than that in the kinematic boundary layer height. The thermodynamic mixed layer is shallowest in the right-rear quadrant, which may be due to the cold wake phenomena. The boundary layer height derived using the critical Richardson number (

R_{i c}

) method shows a similar front-back asymmetry as the kinematic boundary layer height. Full article

(This article belongs to the Special Issue Lower Atmosphere Meteorology)

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17 pages, 4995 KiB

Open AccessArticle

Analysis of a Haze Event over Nanjing, China Based on Multi-Source Data

by Yiyang Zhang, Jing Wang and Lingbing Bu

Atmosphere 2019, 10(6), 338; https://doi.org/10.3390/atmos10060338 - 20 Jun 2019

Cited by 11 | Viewed by 3179

Abstract

We analyzed a June 2018 Nanjing, China haze event using ground-based and spaceborne sensors, combined with sounding and HYSPLIT backward trajectory data, with the ground-based and spaceborne sensor data exhibiting good consistency. Water vapor content showed significant positive correlation with AOD (aerosol optical [...] Read more.

We analyzed a June 2018 Nanjing, China haze event using ground-based and spaceborne sensors, combined with sounding and HYSPLIT backward trajectory data, with the ground-based and spaceborne sensor data exhibiting good consistency. Water vapor content showed significant positive correlation with AOD (aerosol optical depth), and AOD measured in urban and industrial areas was much higher compared to other similar zones. The afternoon convection caused the aerosol uplift during the haze event. Higher aerosol concentration was detected below 2 km. Due to the summer afternoon convective movement, pollutants at high altitude were dominated by small particles, while the overall pollutant mix was dominated by mixed aerosols. During a stable period over June 11–18, a single, near-surface inversion layer, and occasional two inversion layers, stopped pollutant dispersal, with only very stable ocean air mass transport in the southeast direction available. The Air Quality Index drop which took place during June 28–30 was caused by two inversion layers, combined with the immigration of pollutants from inland air masses. Full article

(This article belongs to the Special Issue Remote Sensing of Aerosols)

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17 pages, 7828 KiB

Open AccessArticle

A NOx Emission Model Incorporating Temperature for Heavy-Duty Diesel Vehicles with Urea-SCR Systems Based on Field Operating Modes

by Xin Wang, Guohua Song, Yizheng Wu, Lei Yu and Zhiqiang Zhai

Atmosphere 2019, 10(6), 337; https://doi.org/10.3390/atmos10060337 - 20 Jun 2019

Cited by 21 | Viewed by 5352

Abstract

The selective catalytic reduction (SCR) is the most commonly used technique for decreasing the emissions of nitrogen oxides (NOx) from heavy-duty diesel vehicles (HDDVs). However, the same injection strategy in the SCR system shows significant variations in NOx emissions even at the same [...] Read more.

The selective catalytic reduction (SCR) is the most commonly used technique for decreasing the emissions of nitrogen oxides (NOx) from heavy-duty diesel vehicles (HDDVs). However, the same injection strategy in the SCR system shows significant variations in NOx emissions even at the same operating mode. This kind of heterogeneity poses challenges to the development of emission inventories and to the assessment of emission reductions. Existing studies indicate that these differences are related to the exhaust temperature. In this study, an emission model is established for different source types of HDDVs based on the real-time data of operating modes. Firstly, the initial NOx emission rates (ERs) model is established using the field vehicle emission data. Secondly, a temperature model of the vehicle exhaust based on the vehicle specific power (VSP) and the heat loss coefficient is established by analyzing the influencing factors of the NOx conversion efficiency. Thirdly, the models of NOx emissions and the urea consumption are developed based on the chemical reaction in the SCR system. Finally, the NOx emissions are compared with the real-world emissions and the estimations by the proposed model and the Motor Vehicle Emission Simulator (MOVES). This indicates that the relative error by the proposed method is 12.5% lower than those calculated by MOVES. The characteristics of NOx emissions under different operating modes are analyzed through the proposed model. The results indicate that the NOx conversion rate of heavy-duty diesel trucks (HDDTs) is 39.2% higher than that of urban diesel transit buses (UDTBs). Full article

(This article belongs to the Special Issue Traffic-Related Emissions)

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15 pages, 2496 KiB

Open AccessArticle

Multifractal Detrended Fluctuation Analysis of Temperature Reanalysis Data over Greece

by Kostas Philippopoulos, Nikolaos Kalamaras, Chris G. Tzanis, Despina Deligiorgi and Ioannis Koutsogiannis

Atmosphere 2019, 10(6), 336; https://doi.org/10.3390/atmos10060336 - 20 Jun 2019

Cited by 25 | Viewed by 4949

Abstract

The Multifractal Detrended Fluctuation Analysis (MF-DFA) is used to examine the scaling behavior and the multifractal characteristics of the mean daily temperature time series of the ERA-Interim reanalysis data for a domain centered over Greece. The results showed that the time series from [...] Read more.

The Multifractal Detrended Fluctuation Analysis (MF-DFA) is used to examine the scaling behavior and the multifractal characteristics of the mean daily temperature time series of the ERA-Interim reanalysis data for a domain centered over Greece. The results showed that the time series from all grid points exhibit the same behavior: they have a positive long-term correlation and their multifractal structure is insensitive to local fluctuations with a large magnitude. Special emphasis was given to the spatial distribution of the main characteristics of the multifractal spectrum: the value of the Hölder exponent, the spectral width, the asymmetry, and the truncation type of the spectra. The most interesting finding is that the spatial distribution of almost all spectral parameters is decisively determined by the land–sea distribution. The results could be useful in climate research for examining the reproducibility of the nonlinear dynamics of reanalysis datasets and model outputs. Full article

(This article belongs to the Section Meteorology)

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The area of study and the ERA-Interim reanalysis grid points. Full article ">Figure 2
Original time series (a), deseasonalized time series (b), log-log plot of Fq(s) versus s (c), multifractal spectrum f(α) versus α for the nearest grid point to Athens (38.25° N, 24.00° E) (d) and generalized Hurst exponent h(q) versus q plot (e) Full article ">Figure 3
Original time series (a), deseasonalized time series (b), log-log plot of Fq(s) versus s (c), multifractal spectrum f(α) versus α for the nearest grid point to Kastoria (40.50° N, 21.00° E) (d) and generalized Hurst exponent h(q) versus q plot (e). Full article ">Figure 4
Log-log plots of F2(s) for two grid points located over land (Land1: 39.75° N, 21.75° E, Land2: 37.50° N, 22.50°E) and for two points located over sea (Sea1: 35.25° N, 27.75° E, Sea2: 36.75° N, 21.00° E) along with the linear fit equations and the corresponding coefficient of determination R2 values. Full article ">Figure 5
Multifractal spectral parameters distributions for a0 (a), spectral width (b), asymmetry parameter (c), and truncation type (d). Full article ">Figure 6
Multifractal spectra for the original (right) and for the shuffled (left) time series. The plots are for the closest to Thessaloniki grid point (40.50° N, 23.25° E). Full article ">Figure 7
Spatial distribution of a0 (a), spectral width (b), asymmetry parameter (c), truncation type (d) where (LL: green squares, L: orange squares, S: blue squares, and R: red squares), and h(2) (e). Full article ">

21 pages, 6195 KiB

Open AccessArticle

SST Indexes in the Tropical South Atlantic for Forecasting Rainy Seasons in Northeast Brazil

by Gbèkpo Aubains Hounsou-Gbo, Jacques Servain, Moacyr Araujo, Guy Caniaux, Bernard Bourlès, Diogenes Fontenele and Eduardo Sávio P. R. Martins

Atmosphere 2019, 10(6), 335; https://doi.org/10.3390/atmos10060335 - 19 Jun 2019

Cited by 12 | Viewed by 5596

Abstract

May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the [...] Read more.

May-to-July and February-to-April represent peak rainy seasons in two sub-regions of Northeast Brazil (NEB): Eastern NEB and Northern NEB respectively. In this paper, we identify key oceanic indexes in the tropical South Atlantic for driving these two rainy seasons. In Eastern NEB, the May-to-July rainfall anomalies present a positive relationship with the previous boreal winter sea surface temperature anomalies (SSTA) in the southeast tropical Atlantic (20°–10° S; 10° W–5° E). This positive relationship, which spread westward along the southern branch of the South Equatorial Current, is associated with northwesterly surface wind anomalies. A warmer sea surface temperature in the southwestern Atlantic warm pool increases the moisture flux convergence, as well as its ascending motion and, hence, the rainfall along the adjacent coastal region. For the Northern NEB, another positive relationship is observed between the February-to-April rainfall anomalies and the SSTA of the previous boreal summer in the Atlantic Niño region (3° S–3° N; 20° W–0°). The negative remote relationship noticeable between the Northern NEB rainfall and the concomitant Pacific Niño/Niña follows cold/warm events occurring during the previous boreal summer in the eastern equatorial Atlantic. The southeastern tropical Atlantic and Atlantic Niño SSTA indexes may, then, be useful to predict seasonal rainfall over the Eastern and Northern NEB, respectively, for about a 6 month leading period. The ability of both southeastern tropical Atlantic and Atlantic Niño SSTA indexes to forecast the Eastern and Northern NEB rainfall, with about a 6 month lead time, is improved when these indexes are respectively combined with the Niño3 (5° S–5° N; 150°–90° W) and the northeast subtropical Atlantic (20° N–35° N, 45° W–20° W), mainly from the 1970’s climate shift. Full article

(This article belongs to the Special Issue Tropical Atlantic Variability)

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Climatologies (2000–2015) of surface wind convergence (from Quick Scatterometer (QuikSCAT) and Advanced Scatterometer (ASCAT), 10−6 s−1, shaded) and sea surface temperature (SST; from Objectively Analyzed Air-Sea Fluxes Project- OAFlux, °C, contour) in (a) February-to-April (FMA) and (b) May-to-July (MJJ), which respectively, correspond to the Northern Northeast Brazil (Northern NEB; black box in (a)) and Eastern Northeast Brazil (Eastern NEB; black box in (b)) rainy seasons. The oceanic red box in (b) corresponds to the region used to define the southern intertropical convergence zone (SITCZ) index. (c) Climatological evolution of Northern NEB (red line; 2°–8° S; 37°–50° W) and Eastern NEB (blue line; 5°–11° S; 34.5°–37° W) rainfall (from Global Precipitation Climatology Centre (GPCC), mm month−1); ITCZ position at 30° W (2° S–12° N; red dotted line) and SITCZ index (10−6 s−1; blue dotted line; 3°–10° S; 25°–35° W) for the period of 2000-2015. ITCZ position and SITCZ have been estimated using the high horizontal resolution (0.25 °) QuikSCAT and ASCAT winds data. Full article ">Figure 2
Distributions of the lagged linear correlation/regression (mm month−1/°C) of the gridded SST (from OAFlux) anomalies in (a) November-December-January(−1) (NDJ(−1)) and (b) MJJ(0) with the rainfall anomalies in Eastern NEB (magenta box) during MJJ(0) for the period 1960–2015. The vectors represent the linear regression (mm month−1/m s−1) of the surface wind vectors (u and v; from NCEP) anomalies, with the rainfall anomalies in Eastern NEB. The correlations that are significant at the 95% confidence level, according to the t-test, are plotted for both SST and wind. Contours indicate regions of correlation higher than +0.5 (solid black line) for SSTA. The diagonal band in <a href="#atmosphere-10-00335-f002" class="html-fig">Figure 2</a>a indicates the pathway of the northwestward propagation of SSTA. Longitude–time diagrams of the composites of standardized SSTA for: (c) WET years, (d) DRY years and (e) difference WET–DRY years for the period 1960–2015. The SSTA are averaged along the latitude of the diagonal band in <a href="#atmosphere-10-00335-f002" class="html-fig">Figure 2</a>a. Contours represent values significant at a 95% confidence level using the t-test. The vertical black lines (at 35° W) in (b–d) indicate the eastern limit of the Eastern NEB. Full article ">Figure 3
(a–c) the Same as in <a href="#atmosphere-10-00335-f002" class="html-fig">Figure 2</a> (c–e), but for the gridded vertically integrated moisture flux convergence (MFC) anomalies (mm month−1/106 kg m−2 s−1). Full article ">Figure 4
Distribution of the lagged linear correlation/regression of the gridded (a) SST (shaded; °C/°C) and surface wind (vectors; m s−1/°C) anomalies (b) 500 hPa vertical velocity (shaded; Pa s−1/°C; negative values indicate upward motion) and the sea level pressure (contours, significant correlation only) anomalies within the entire tropical Atlantic in MJJ with SSTA inside southeastern tropical Atlantic (SETA; 10° S–20° S, 10° W–5° E; oceanic black box) in NDJ for all the years (56 years) from 1960 to 2015. Only the correlations that are significant at a 95% confidence level, according to the t-test, are plotted for all variables. Contours in (a) indicate regions of correlation higher than +0.5 for SSTA. Full article ">Figure 5
Distributions of lagged linear correlation/regression (mm month−1/°C) of the gridded SSTA in: (a) JAS(−1) and (b) FMA(0) with rainfall anomalies in Northern NEB (red box) during FMA(0) for the period 1960–2015. The vectors represent the linear regression (mm month−1/m s−1) of the gridded surface wind vectors (u and v) with rainfall anomalies in Northern NEB. The significant correlations at a 95% confidence level, according to the t-test, are plotted for both SST and wind. Contours indicate regions of correlation higher than +0.5 (solid black line) and lower than −0.5 (solid gray line). Longitude–time diagrams of the composites of standardized SSTA for: (c) WET years, (d) DRY years, and (e) difference WET–DRY years for the period 1960–2015. The SSTA are averaged between 60° W–15° E. Values in <a href="#atmosphere-10-00335-f005" class="html-fig">Figure 5</a>d are shown where the difference is significant at a 95% confidence level using the t-test. (f) Running correlation of 25 year (centered) windows between JAS(−1) Atlantic Niño (ATL3) SSTA and FMA(0) Northern NEB rainfall anomalies. Dots indicate correlation significant at a 95% confidence level according to the t-test. Full article ">Figure 6
Latitude–time diagram of lagged linear correlation/regression between the rainfall anomalies in Northern NEB during FMA(0) and (a) SSTA (mm month−1/°C) (b) surface wind speed anomalies (mm month−1/m s−1) for the period 1980–2015. The SST and wind speed anomalies are averaged between 60° W–15° E. Values shown are significant at the 95% confidence level using the t-test. Contours indicate regions of correlation higher than +0.5 (solid line) and lower than −0.5 (dotted line) for (a,b). Full article ">Figure 7
Distribution of the lagged linear correlation/regression of the gridded (a) SST (°C/°C, shaded) and surface wind (u and v, m s−1/°C, vectors) anomalies (b) velocity potential at 200 hPa (shaded) and stream function at 200 hPa (contours) anomalies over the global ocean in FMA(0) with SSTA inside ATL3 (oceanic black box) in JAS(−1) for all the years (36 years) during 1980–2015. The correlations that are significant at a 95% confidence level, according to the t-test, are plotted for both SST and wind. Contours indicate regions of correlation higher than +0.5 for SST (a). The continental black box indicates the Northern NEB region. Full article ">Figure 8
Seasonal evolution of the lagged linear correlation coefficient between (a) MJJ rainfall anomalies in Eastern NEB and the SETA (red line), the NINO3 (green line), the tropical South Atlantic (TSA, 20° S–0°; 40° W–15° E, red dashed line), and the tropical North Atlantic (TNA, 0°–20° N; 60°–15° W, blue dashed line) SSTA for the period 1980–2015, (b) FMA rainfall anomalies in Northern NEB and the ATL3 (red line), the NINO3 (green line), the Atlantic dipole (blue line; tropical North Atlantic—tropical South Atlantic (TNA-TSA)), the TSA (red dashed line), and the TNA (blue dashed line) SSTA for the period 1980–2015. Correlations higher than ± 0.32 are significant at a 95% confidence level, according to the t-test, for (a,b). Full article ">

19 pages, 5767 KiB

Open AccessArticle

A New Approach for Generating Human Biometeorological Information Based on Gridded High-Resolution Data (Basic Data of Test-Reference-Years)

by Irmela C. Schlegel and Andreas Matzarakis

Atmosphere 2019, 10(6), 334; https://doi.org/10.3390/atmos10060334 - 19 Jun 2019

Cited by 2 | Viewed by 3216

Abstract

The assessment of human-biometeorological information requires appropriate preparation of data and suitable visualisation of results. Human-biometeorological information can be valuable for tourists and visitors, but also for citizens looking for information about their neighbourhood or a new residence. Cities or health resorts can [...] Read more.

The assessment of human-biometeorological information requires appropriate preparation of data and suitable visualisation of results. Human-biometeorological information can be valuable for tourists and visitors, but also for citizens looking for information about their neighbourhood or a new residence. Cities or health resorts can also promote their climate conditions for health rehabilitation. To derive this human-biometeorological information in a unified, comprehensive, and comprehensible form, a tool was developed. The input information contains the coordinates of a place and/or area of interest, and the time period of data chosen by the user. For meteorological data, the basic dataset of Test-Reference-Years from the German Meteorological Service is used, containing hourly meteorological data for the time period from 1995 to 2012, covering Germany with a spatial resolution of 1 km². Based on the Perceived Temperature as a thermal index, days with heat stress and cold stimulus are identified. In this process, the effects of short-term human acclimatisation on the thermal environment are considered by using a variable threshold value based on the thermal conditions of the last 30 days. The results of the tool’s application consist of several frequency diagrams, the Climate-Tourism/Transfer-Information-Scheme, a diagram of heat waves, and maps of the area of interest, displaying the spatial distribution of heat stress and cold stimulus. As an example, the (bio-)meteorological conditions of the region of southern Baden around Freiburg and the Black Forest, including the health resort, Hinterzarten, are analysed. Full article

(This article belongs to the Special Issue Natural Hazards―Lessons from The Past and Contemporary Challenges)

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14 pages, 3190 KiB

Open AccessArticle

MODIS Cloud Detection Evaluation Using CALIOP over Polluted Eastern China

by Saichun Tan, Xiao Zhang and Guangyu Shi

Atmosphere 2019, 10(6), 333; https://doi.org/10.3390/atmos10060333 - 19 Jun 2019

Cited by 7 | Viewed by 3455

Abstract

Haze pollution has frequently occurred in winter over Eastern China in recent years. Over Eastern China, Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection data were compared with the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) for three years (2013–2016) for three kinds of underlying [...] Read more.

Haze pollution has frequently occurred in winter over Eastern China in recent years. Over Eastern China, Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection data were compared with the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) for three years (2013–2016) for three kinds of underlying surface types (dark, bright, and water). We found that MODIS and CALIOP agree most of the time (82% on average), but discrepancies occurred at low CALIOP cloud optical thickness (COT < 0.4) and low MODIS cloud top height (CTH < 1.5 km). In spring and summer, the CALIOP cloud fraction was higher by more than 0.1 than MODIS due to MODIS’s incapability of observing clouds with a lower COT. The discrepancy increased significantly with a decrease in MODIS CTH and an increase in aerosol optical depth (AOD, about 2–4 times), and MODIS observed more clouds that were undetected by CALIOP over PM_2.5 > 75 μg m⁻³ regions in autumn and particularly in winter, suggesting that polluted weather over Eastern China may contaminate MODIS cloud detections because MODIS will misclassify a heavy aerosol layer as cloudy under intense haze conditions. Besides aerosols, the high solar zenith angle (SZA) in winter also affects MODIS cloud detection, and the ratio of MODIS cloud pixel numbers to CALIOP cloud-free pixel numbers at a high SZA increased a great deal (about 4–21 times) relative to that at low SZA for the three surfaces. As a result of the effects of aerosol and SZA, MODIS cloud fraction was 0.08 higher than CALIOP, and MODIS CTH was more than 2 km lower than CALIOP CTH in winter. As for the cloud phases and types, the results showed that most of the discrepancies could be attributed to water clouds and low clouds (cumulus and stratocumulus), which is consistent with most of the discrepancies at low MODIS CTH. Full article

(This article belongs to the Special Issue Advances in Atmospheric Lidar Remote Sensing)

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14 pages, 5449 KiB

Open AccessArticle

Emissions Characteristics of Hazardous Air Pollutants from the Incineration of Sacrificial Offerings

by Shihao Zhang, Lianhong Zhong, Xi Chen, Yanan Liu, Xiaoman Zhai, Yifeng Xue, Wei Wang, Jie Liu and Kangli Xu

Atmosphere 2019, 10(6), 332; https://doi.org/10.3390/atmos10060332 - 18 Jun 2019

Cited by 10 | Viewed by 4477

Abstract

The incineration of sacrificial offerings generates numerous hazardous air pollutants, including particulate matter (PM), CO, SO₂, NOx and non-methane hydrocarbons (NMHC), which has significant effects on the environment and human health. However, due to the concealment of sacrificial offerings incineration, [...] Read more.

The incineration of sacrificial offerings generates numerous hazardous air pollutants, including particulate matter (PM), CO, SO₂, NOx and non-methane hydrocarbons (NMHC), which has significant effects on the environment and human health. However, due to the concealment of sacrificial offerings incineration, the emission of such pollutants has not received sufficient attention. Relevant quantification of the emission, emission factors and pollution control measures for this pollution source are lacking. To address these problems, herein, we quantified the particulate matter and its chemical composition and the emission levels of gaseous pollutants, including SO₂, NOx, NMHC and CO, by performing incineration experiments of four typical sacrificial offerings (Joss paper, Funeral wreath, Taoist paper art and Yuanbao paper), and obtained the emission factors and emission characteristics for the incineration of sacrificial offerings. Therefore, this study lays the foundation and provides support for establishing an emission inventory of the air pollutants from the incineration of sacrificial offerings and introducing corresponding pollution control measures. The results show that the emission concentrations of CO and total suspended particulate (TSP) from the incineration of sacrificial offerings greatly exceed the emission standard, with averages of 621.4 mg m⁻³ and 142.9 mg m⁻³ at 11% oxygen content, respectively. The average emission factors of SO₂, NOx, NMHC, CO, PM₁₀ and PM_2.5 for the incineration of the four offerings are (0.47 ± 0.17) kg t⁻¹, (2.46 ± 0.35) kg t⁻¹, (5.78 ± 2.41) kg t⁻¹, (32.40 ± 8.80) kg t⁻¹, (4.23 ± 0.71) kg t⁻¹ and (2.62 ± 0.48) kg t⁻¹, respectively, among which the emission intensities of NMHC and CO are relatively high. Among the different types of sacrificial offerings, the overall average emission factor of air pollutants generated from the incineration of Yuanbao paper is the highest, which is mainly due to the low burning efficiency and the coating material. For the chemical composition of the particulate matters, ions, OC, EC and metal elements account for proportions of the PM_2.5 at (23.55 ± 10.37) %, (29.74 ± 9.95) %, (14.83 ± 6.55) % and (13.45 ± 4.88) %, respectively, indicating that the organic pollution is severe Full article

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Graphical abstract

Graphical abstract
Full article ">Figure 1
Sites of the incinerator for sacrificial offerings. Full article ">Figure 2
Four types of sacrificial offerings used in the experiment. Full article ">Figure 3
Pollutant-monitoring platform for the incineration of sacrificial offerings. Full article ">Figure 4
Emission concentration variations of the gaseous pollutants from the incineration of the four sacrificial offerings: (a) Joss paper; (b) Funeral wreath; (c) Taoist paper art; (d) Yuanbao paper. Full article ">Figure 5
Average emission concentrations of pollutants from the incineration of the four sacrificial offerings. Full article ">Figure 6
Emission factors of hazardous air pollutants from the incineration of sacrificial offerings. Full article ">Figure 7
Percentages of chemical components in PM2.5 generated from the incineration of sacrificial offerings: (a) Joss paper; (b) Funeral wreath; (c) Taoist paper art; (d) Yuanbao paper. Full article ">Figure 8
Concentrations of EC and OC in PM2.5 generated from the incineration of sacrificial offerings. Full article ">Figure 9
Concentrations and percentages of water-soluble ions in PM2.5 generated from the incineration of sacrificial offerings. Full article ">Figure 10
Concentrations of elements in the PM2.5 generated from the incineration of sacrificial offerings. Full article ">

11 pages, 1187 KiB

Open AccessArticle

Assessing the Wet Deposition Mechanism of Benzo(a)pyrene in the Atmosphere by MF-DCCA

by Chunqiong Liu, Kai Shi, Jian Liang and Hongliang Huang

Atmosphere 2019, 10(6), 331; https://doi.org/10.3390/atmos10060331 - 18 Jun 2019

Cited by 4 | Viewed by 2498

Abstract

Based on the 19 year observation from 1998 to 2016 at the Tsuan Wan and Central/Western District monitoring stations in Hong Kong, the aim of this paper was to assess the wet deposition pathway of Benzo(a)pyrene (BaP) on a large time-scale. In order [...] Read more.

Based on the 19 year observation from 1998 to 2016 at the Tsuan Wan and Central/Western District monitoring stations in Hong Kong, the aim of this paper was to assess the wet deposition pathway of Benzo(a)pyrene (BaP) on a large time-scale. In order to achieve this goal, multi-fractal detrended cross-correlation analysis (MF-DCCA) was used to characterize the long-term cross-correlations behaviors and multi-fractal temporal scaling properties between BaP (or PM_2.5) and precipitation. The results showed that the relationships between BaP and precipitation (or PM_2.5) displayed long-term cross-correlation at the time-scale ranging from one month to one year; no cross-correlation between each other was observed in longer temporal scaling regimes (greater than one year). These results correspond to the atmospheric circulation of the Asian monsoon system and are explained in detail. Similar dynamic processes of the wet deposition of BaP and PM_2.5 suggested that the main removal process of atmospheric BaP was rainfall deposits of PM_2.5-bound BaP. Furthermore, cross-correlations between BaP (or PM_2.5) and precipitation at the long time-scale have a multi-fractal nature and long-term persistent power-law decaying behavior. The temporal evolutions of the multi-fractality were investigated by the approach of a sliding window. Based on the evolution curves of multi-fractal parameters, the wet deposition pathway of PM_2.5-bound BaP is discussed. Finally, the contribution degree of wet deposition to PM_2.5-bound BaP was derived from the coefficient of determination. It was demonstrated that about 45% and 60% of atmospheric BaP removal can be attributed to the wet deposition pathway of PM_2.5-bound BaP for the Tsuan Wan and Central/Western District areas, respectively. The findings in this paper are of great significance for further study on the removal mechanism of atmospheric BaP in the future. The MF-DCCA method provides a novel approach to assessing the geochemical cycle dynamics of BaP. Full article

(This article belongs to the Section Air Quality)

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17 pages, 3270 KiB

Open AccessArticle

Pollution Events at the High-Altitude Mountain Site Zugspitze-Schneefernerhaus (2670 m a.s.l.), Germany

by Homa Ghasemifard, Felix R. Vogel, Ye Yuan, Marvin Luepke, Jia Chen, Ludwig Ries, Michael Leuchner, Christian Schunk, Sanam Noreen Vardag and Annette Menzel

Atmosphere 2019, 10(6), 330; https://doi.org/10.3390/atmos10060330 - 18 Jun 2019

Cited by 12 | Viewed by 5021

Abstract

Within the CO₂ time series measured at the Environmental Research Station Schneefernerhaus (UFS), Germany, as part of the Global Atmospheric Watch (GAW) program, pollution episodes are traced back to local and regional emissions, identified by δ¹³C(CO₂) as well [...] Read more.

Within the CO₂ time series measured at the Environmental Research Station Schneefernerhaus (UFS), Germany, as part of the Global Atmospheric Watch (GAW) program, pollution episodes are traced back to local and regional emissions, identified by δ¹³C(CO₂) as well as ratios of CO and CH₄ to CO₂ mixing ratios. Seven episodes of sudden enhancements in the tropospheric CO₂ mixing ratio are identified in the measurements of mixing/isotopic ratios during five winter months from October 2012 to February 2013. The short-term CO₂ variations are closely correlated with changes in CO and CH₄ mixing ratios, achieving mean values of 6.0 ± 0.2 ppb/ppm for CO/CO₂ and 6.0 ± 0.1 ppb/ppm for CH₄/CO₂. The estimated isotopic signature of CO₂ sources (δ_s) ranges between −35‰ and −24‰, with higher values indicating contributions from coal combustion or wood burning, and lower values being the result of natural gas or gasoline. Moving Keeling plots with site-specific data selection criteria are applied to detect these pollution events. Furthermore, the HYSPLIT trajectory model is utilized to identify the trajectories during periods with CO₂ peak events. Short trajectories are found covering Western and Central Europe, while clean air masses flow from the Atlantic Ocean and the Arctic Ocean. Full article

(This article belongs to the Special Issue High Altitude Site Observations of the Atmospheric Chemical Composition)

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Source signature determination using the Keeling plot. (a) The CO2 mixing ratio (solid line) and δ13C (dashed line) of event E7, and (b) the Keeling plot for the entire event as shown in (a). The y-intercept and coefficient of determination R2 of the fitted linear regressions following Equation (3) are given in (b). Full article ">Figure 2
Temporal variation of the mixing ratios of CO2, CO, and CH4, as well as the stable carbon isotope ratio of atmospheric CO2 (δ13C), for five months at the Environmental Research Station Schneefernerhaus (UFS). The arrows point to the studied episodes labeled E1–E7. The shaded areas indicate distinct pollution events (the first event actually contains separate two events, but due to the short period between them the shaded area is shown as a single event). Full article ">Figure 3
Intercepts of Keeling plots (δs) during the individual pollution events. (a) Results of the classical Keeling plot method. Black circles indicate the intercept and the error bars show the error of the intercept. (b) Results of moving the Keeling plot method depicted as box plots. The whiskers of the boxplots indicate the minimum and maximum values, the lower and upper boundaries of the boxes are the 25th- and 75th-percentiles, and the horizontal lines inside boxes represent medians. Full article ">Figure 4
Linear regressions of the hourly mean mixing ratios of CO and CO2 for the five pollution events E3–E7 (CO data not available for E1 and E2). The slope and coefficient of determination R2 are given. The shaded areas around the regression lines represent the range in which the true regression line lies at a certain level of confidence (95% in the plot). The slope of the regressions corresponds to CO/CO2 emission ratios. Full article ">Figure 5
Linear regressions of hourly mean mixing ratios of CH4 and CO2 for four pollution events (CH4 data not available for E1, E2, and E6). The slope and coefficient of determination R2 are given. The shaded areas around the regressions line represent the range in which the true regression line lies at a certain level of confidence (95% in the plot). The slope of the regressions corresponds to CH4/CO2 emission ratios. Full article ">Figure 6
HYSPLIT backward trajectories (1-h interval) of air masses reaching the UFS during pollution events E1 and E2. The three plots are 24 h before the events (left panel), E1 and E2 combined during the events (middle panel), and 24 h after the events (right panel). The color of the trajectories shows the respective height above ground level (m). Full article ">Figure 7
Potential source contribution function (PSCF) plot of CO2. The color of the maps shows the respective probabilities. For each event (E3 to E7), three plots are shown including 24 h before the event, during the event, and 24 h after the event (left, center, and right, respectively). Blue to purple colors (0 ≤ Pij ≤ 1) identify regions from which elevated CO2 potentially originated. Black circles show the position of the UFS study site. Full article ">

2 pages, 143 KiB

Open AccessEditorial

Large-Scale Atmospheric Circulation Variability and Its Climate Impacts

by Bin Yu and Anthony R. Lupo

Atmosphere 2019, 10(6), 329; https://doi.org/10.3390/atmos10060329 - 18 Jun 2019

Cited by 6 | Viewed by 2977

Abstract

This special issue collects original and review articles on large-scale atmospheric circulation variability and its climate impacts [...] Full article

(This article belongs to the Special Issue Large-Scale Atmospheric Circulation Variability and Its Climate Impacts)

15 pages, 3554 KiB

Open AccessArticle

Feasibility of the Inverse-Dispersion Model for Quantifying Drydock Emissions

by Bhaskar Kura and Abhinay Jilla

Atmosphere 2019, 10(6), 328; https://doi.org/10.3390/atmos10060328 - 17 Jun 2019

Cited by 4 | Viewed by 2923

Abstract

Important processes within the shipbuilding and ship repair industry include metal cutting, welding, surface preparation, and painting. When dealing with ship repair, ships are brought into drydocks to carry out necessary repairs. Typical repairs include but are not limited to dry or wet [...] Read more.

Important processes within the shipbuilding and ship repair industry include metal cutting, welding, surface preparation, and painting. When dealing with ship repair, ships are brought into drydocks to carry out necessary repairs. Typical repairs include but are not limited to dry or wet abrasive blasting for removing the old paint and rust followed by repainting of the external hull. Also, the painting of superstructure is carried out as necessary. Additionally, many metal cutting and welding operations are carried out. Air pollutant emissions generated from repair operations carried out within drydock are challenging to quantify, particularly if some of these repair activities do not have reliable emission factors. This paper investigates the feasibility of the inverse dispersion model for quantifying drydock emissions in a shipyard environment. The authors use a well-established Gaussian dispersion model that is used as a regulatory model in the United States and many other countries in a two-step process using a code developed in MATLAB: (1) Source-to-Receptor modeling to compute ambient concentrations using assumed emissions from various sources and meteorological conditions, and (2) The utilization of the computed ambient concentrations at various receptors to compute emissions at those sources (assumed in the first step) using the inverse Gaussian code developed. Full article

(This article belongs to the Section Air Quality)

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15 pages, 4017 KiB

Open AccessArticle

Atmospheric Forcing of Coastal Upwelling in the Southern Baltic Sea Basin

by Ewa Bednorz, Marek Półrolniczak, Bartosz Czernecki and Arkadiusz M. Tomczyk

Atmosphere 2019, 10(6), 327; https://doi.org/10.3390/atmos10060327 - 17 Jun 2019

Cited by 9 | Viewed by 2962

Abstract

This study analyzes the atmospheric forcing of upwelling occurrence along differently oriented coastlines of the southern Baltic Sea basin. The mean daily sea surface temperature (SST) data from the summer seasons (June–August) of the years 1982–2017 made the basis for the detection of [...] Read more.

This study analyzes the atmospheric forcing of upwelling occurrence along differently oriented coastlines of the southern Baltic Sea basin. The mean daily sea surface temperature (SST) data from the summer seasons (June–August) of the years 1982–2017 made the basis for the detection of upwelling cases. For the atmospheric part of the analysis, monthly indices of four macroscale circulation patterns were used: North Atlantic Oscillation (NAO), Scandinavian (SCAND), East Atlantic (EA) and East Atlantic/Western Russia (EATL/WRUS). In order to identify the local airflows and wind conditions, zonal and meridional regional circulation indices were constructed and introduced to the analysis. Within the southern Baltic Sea basin, upwelling occurs most frequently along the zonally oriented southern coasts of Sweden, and least frequently along the southern (Polish) and eastern (Lithuanian-Latvian) coasts. Among the macroscale circulation patterns, the SCAND has the strongest impact on the horizontal flow of surface sea waters in the southern Baltic, which triggers upwelling. The summer NAO and EA appeared to have a weak effect on upwelling occurrence, and EATL/WRUS have the smallest impact. Local circulation indices allowed us to recognize the atmospheric control of upwelling frequency better than the indices of the macroscale patterns. Anomalies in upwelling frequency are their highest at the positive/negative phase of the zonal circulation, particularly along the southern and eastern coast of the southern Baltic Sea basin. Full article

(This article belongs to the Section Meteorology)

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22 pages, 6843 KiB

Open AccessArticle

CFD Simulation of the Wind Field in Jinjiang City Using a Building Data Generalization Method

by Mengxi Li, Xinfa Qiu, Juanjun Shen, Jinqin Xu, Bo Feng, Yongjian He, Guoping Shi and Xiaochen Zhu

Atmosphere 2019, 10(6), 326; https://doi.org/10.3390/atmos10060326 - 16 Jun 2019

Cited by 17 | Viewed by 6270

Abstract

The urban wind environment is an important element of urban microclimates and plays an important role in the quality of the urban environment. The computational fluid dynamics (CFD) simulation method is an important means for urban wind field research. However, CFD simulation has [...] Read more.

The urban wind environment is an important element of urban microclimates and plays an important role in the quality of the urban environment. The computational fluid dynamics (CFD) simulation method is an important means for urban wind field research. However, CFD simulation has high requirements for computer hardware and software. In this paper, based on geographic information system (GIS) technology, a new building data generalization method was developed to solve the problems of a huge amount of data and calculations in urban-scale CFD wind field simulations. Using Fluent software and high-precision urban building geographic information data with elevation attributes, the method was applied to Jinjiang City, Fujian Province, China. A CFD simulation of the wind field of Jinjiang City was implemented, and detailed, intuitive wind field information was obtained, which were compared with the measured data. The results show that the building data generalization method could effectively improve the efficiency of the city's overall wind field CFD simulation. The simulated wind speed was significantly correlated with the measured data, but it was overestimated. The simulated wind direction was consistent with the measured data of most stations. The simulation results were reasonable and could provide reference for application and subsequent research. Full article

(This article belongs to the Section Biometeorology and Bioclimatology)

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21 pages, 9694 KiB

Open AccessArticle

Radar-Based Automatic Identification and Quantification of Weak Echo Regions for Hail Nowcasting

by Junzhi Shi, Ping Wang, Di Wang and Huizhen Jia

Atmosphere 2019, 10(6), 325; https://doi.org/10.3390/atmos10060325 - 14 Jun 2019

Cited by 12 | Viewed by 4087

Abstract

The identification of some radar reflectivity signatures plays a vital role in severe thunderstorm nowcasting. A weak echo region is one of the signatures that could indicate updraft, which is a fundamental condition for hail production. However, this signature is underutilized in automatic [...] Read more.

The identification of some radar reflectivity signatures plays a vital role in severe thunderstorm nowcasting. A weak echo region is one of the signatures that could indicate updraft, which is a fundamental condition for hail production. However, this signature is underutilized in automatic forecasting systems due to the lack of a reliable detection method and the uncertain relationships between different weak echo regions and hail-producing thunderstorms. In this paper, three algorithms related to weak echo regions are proposed. The first is a quasi-real-time weak echo region morphology identification algorithm using the radar echo bottom height image. The second is an automatic vertical cross-section-making algorithm. It provides a convenient tool for automatically determining the location of a vertical cross-section that exhibits a visible weak echo region to help forecasters assess the vertical structures of thunderstorms with less time consumption. The last is a weak echo region quantification algorithm mainly used for hail nowcasting. It could generate a parameter describing the scale of a weak echo region to distinguish hail and no-hail thunderstorms. Evaluation with real data of the Tianjin radar indicates that the critical success index of the weak echo region identification algorithm is 0.61. Statistics on these data also show that when the weak echo region parameters generated by the quantification algorithm are in a particular range, more than 85% of the convective cells produced hail. Full article

(This article belongs to the Special Issue Weather Radar Observations of Severe Storms)

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20 pages, 6177 KiB

Open AccessArticle

An Assessment of Coordinate Rotation Methods in Sonic Anemometer Measurements of Turbulent Fluxes over Complex Mountainous Terrain

by Alessio Golzio, Irene Maria Bollati and Silvia Ferrarese

Atmosphere 2019, 10(6), 324; https://doi.org/10.3390/atmos10060324 - 13 Jun 2019

Cited by 14 | Viewed by 3879

Abstract

The measurement of turbulent fluxes in the atmospheric boundary layer is usually performed using fast anemometers and the Eddy Covariance technique. This method has been applied here and investigated in a complex mountainous terrain. A field campaign has recently been conducted at Alpe [...] Read more.

The measurement of turbulent fluxes in the atmospheric boundary layer is usually performed using fast anemometers and the Eddy Covariance technique. This method has been applied here and investigated in a complex mountainous terrain. A field campaign has recently been conducted at Alpe Veglia (the Central-Western Italian Alps, 1746 m a.s.l.) where both standard and micrometeorological data were collected. The measured values obtained from an ultrasonic anemometer were analysed using a filtering procedure and three different coordinate rotation procedures: Double (DR), Triple Rotation (TR) and Planar Fit (PF) on moving temporal windows of 30 and 60 min. A quality assessment was performed on the sensible heat and momentum fluxes and the results show that the measured turbulent fluxes at Alpe Veglia were of a medium-high quality level and rarely passed the stationary flow test. A comparison of the three coordinate procedures, using quality assessment and sensible heat flux standard deviations, revealed that DR and TR were comparable, with significant differences, mainly under low-wind conditions. The PF method failed to satisfy the physical requirement for the multiple planarity of the flow, due to the complexity of the mountainous terrain. Full article

(This article belongs to the Special Issue Turbulence in Atmospheric Boundary Layers)

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23 pages, 2613 KiB

Open AccessEditor’s ChoiceArticle

Black Carbon and Particulate Matter Concentrations in Eastern Mediterranean Urban Conditions: An Assessment Based on Integrated Stationary and Mobile Observations

by Tareq Hussein, Shatha Suleiman Ali Saleh, Vanessa N. dos Santos, Huthaifah Abdullah and Brandon E. Boor

Atmosphere 2019, 10(6), 323; https://doi.org/10.3390/atmos10060323 - 13 Jun 2019

Cited by 16 | Viewed by 5455

Abstract

There is a paucity of comprehensive air quality data from urban areas in the Middle East. In this study, portable instrumentation was used to measure size-fractioned aerosol number, mass, and black carbon concentrations in Amman and Zarqa, Jordan. Submicron particle number concentrations at [...] Read more.

There is a paucity of comprehensive air quality data from urban areas in the Middle East. In this study, portable instrumentation was used to measure size-fractioned aerosol number, mass, and black carbon concentrations in Amman and Zarqa, Jordan. Submicron particle number concentrations at stationary urban background sites in Amman and Zarqa exhibited a characteristic diurnal pattern, with the highest concentrations during traffic rush hours (2–5 × 10⁴ cm⁻³ in Amman and 2–7 × 10⁴ cm⁻³ in Zarqa). Super-micron particle number concentrations varied considerably in Amman (1–10 cm⁻³). Mobile measurements identified spatial variations and local hotspots in aerosol levels within both cities. Walking paths around the University of Jordan campus showed increasing concentrations with proximity to main roads with mean values of 8 × 10⁴ cm⁻³, 87 µg/m³, 62 µg/m³, and 7.7 µg/m³ for submicron, PM₁₀, PM_2.5, and black carbon (BC), respectively. Walking paths in the Amman city center showed moderately high concentrations (mean 10⁵ cm⁻³, 120 µg/m³, 85 µg/m³, and 8.1 µg/m³ for submicron aerosols, PM₁₀, PM_2.5, and black carbon, respectively). Similar levels were found along walking paths in the Zarqa city center. On-road measurements showed high submicron concentrations (>10⁵ cm⁻³). The lowest submicron concentration (<10⁴ cm⁻³) was observed near a remote site outside of the cities. Full article

(This article belongs to the Special Issue Ambient Aerosol Measurements in Different Environments)

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Graphical abstract

Graphical abstract
Full article ">Figure 1
Workday diurnal patterns of submicron particle number concentrations (PN1–0.01) measured at the reference urban background sites during the pre-campaigns: (a) the campus of the University of Jordan and (b) Ma’asom in Zarqa. Full article ">Figure 2
Super-micron particle number concentrations (PN10–1) measured at the reference urban background (campus of the University of Jordan) and compared to that measured with the mobile measurement campaigns. Full article ">Figure 3
Submicron particle number concentrations (PN1–0.01) measured during mobile campaigns on May 29th and continued on May 30th. The results are plotted along with the diurnal pattern observed at the reference urban background (campus of the University of Jordan). Full article ">Figure 4
Submicron particle number concentrations (PN1–0.01) measured during mobile campaigns on (a) June 1st and (b) June 2nd. The results are plotted along with the diurnal patterns observed at the reference urban background (campus of the University of Jordan). Full article ">Figure 5
Submicron particle number concentrations (PN1–0.01) measured during walking mobile campaign in Zarqa city center on June 3rd. The results are plotted along with the diurnal pattern observed at the reference urban background (Ma’asom in Zarqa). Full article ">

19 pages, 7968 KiB

Open AccessArticle

Explosive Cyclogenesis around the Korean Peninsula in May 2016 from a Potential Vorticity Perspective: Case Study and Numerical Simulations

by Ki-Young Heo, Kyung-Ja Ha and Taemin Ha

Atmosphere 2019, 10(6), 322; https://doi.org/10.3390/atmos10060322 - 12 Jun 2019

Cited by 8 | Viewed by 5130

Abstract

An explosive cyclone event that occurred near the Korean Peninsula in early May 2016 is simulated using the Weather Research and Forecasting (WRF) model to examine the developmental mechanisms of the explosive cyclone. After confirming that the WRF model reproduces the synoptic environments [...] Read more.

An explosive cyclone event that occurred near the Korean Peninsula in early May 2016 is simulated using the Weather Research and Forecasting (WRF) model to examine the developmental mechanisms of the explosive cyclone. After confirming that the WRF model reproduces the synoptic environments and main features of the event well, the favorable environmental conditions for the rapid development of the cyclone are analyzed, and the explosive development mechanisms of the cyclone are investigated with perturbation potential vorticity (PV) fields. The piecewise PV inversion method is used to identify the dynamically relevant meteorological fields associated with each perturbation PV anomaly. The rapid deepening of the surface cyclone was influenced by both adiabatic (an upper tropospheric PV anomaly) and diabatic (a low-level PV anomaly associated with condensational heating) processes, while the baroclinic processes in the lower troposphere had the smallest contribution. In the explosive phase of the cyclone life cycle, the diabatically generated PV anomalies associated with condensational heating induced by the ascending air in the warm conveyor belt are the most important factors for the initial intensity of the cyclone. The upper-level forcing is the most important factor in the evolution of the cyclone’s track, but it is of secondary importance for the initial strong deepening. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Current Developments)

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15 pages, 2287 KiB

Open AccessArticle

Precipitation Evolution over Belgium by 2100 and Sensitivity to Convective Schemes Using the Regional Climate Model MAR

by Sébastien Doutreloup, Christoph Kittel, Coraline Wyard, Alexandre Belleflamme, Charles Amory, Michel Erpicum and Xavier Fettweis

Atmosphere 2019, 10(6), 321; https://doi.org/10.3390/atmos10060321 - 12 Jun 2019

Cited by 4 | Viewed by 3744

Abstract

The first aim of this study is to determine if changes in precipitation and more specifically in convective precipitation are projected in a warmer climate over Belgium. The second aim is to evaluate if these changes are dependent on the convective scheme used. [...] Read more.

The first aim of this study is to determine if changes in precipitation and more specifically in convective precipitation are projected in a warmer climate over Belgium. The second aim is to evaluate if these changes are dependent on the convective scheme used. For this purpose, the regional climate model Modèle Atmosphérique Régional (MAR) was forced by two general circulation models (NorESM1-M and MIROC5) with five convective schemes (namely: two versions of the Bechtold schemes, the Betts–Miller–Janjić scheme, the Kain–Fritsch scheme, and the modified Tiedtke scheme) in order to assess changes in future precipitation quantities/distributions and associated uncertainties. In a warmer climate (using RCP8.5), our model simulates a small increase of convective precipitation, but lower than the anomalies and the interannual variability over the current climate, since all MAR experiments simulate a stronger warming in the upper troposphere than in the lower atmospheric layers, favoring more stable conditions. No change is also projected in extreme precipitation nor in the ratio of convective precipitation. While MAR is more sensitive to the convective scheme when forced by GCMs than when forced by ERA-Interim over the current climate, projected changes from all MAR experiments compare well. Full article

(This article belongs to the Special Issue Precipitation and Climate Change: Accomplishments and Challenges)

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13 pages, 5823 KiB

Open AccessArticle

OPERA the Radar Project

by Elena Saltikoff, Günther Haase, Laurent Delobbe, Nicolas Gaussiat, Maud Martet, Daniel Idziorek, Hidde Leijnse, Petr Novák, Maryna Lukach and Klaus Stephan

Atmosphere 2019, 10(6), 320; https://doi.org/10.3390/atmos10060320 - 12 Jun 2019

Cited by 49 | Viewed by 8690

Abstract

The Operational Program on the Exchange of Weather Radar Information (OPERA) has co-ordinated radar co-operation among national weather services in Europe for more than 20 years. It has introduced its own, manufacturer-independent data model, runs its own data center, and produces Pan-European radar [...] Read more.

The Operational Program on the Exchange of Weather Radar Information (OPERA) has co-ordinated radar co-operation among national weather services in Europe for more than 20 years. It has introduced its own, manufacturer-independent data model, runs its own data center, and produces Pan-European radar composites. The applications using this data vary from data assimilation to flood warnings and the monitoring of animal migration. It has used several approaches to provide a homogeneous combination of disparate raw data and to indicate the reliability of its products. In particular, if a pixel shows no precipitation, it is important to know if that pixel is dry or if the measurement was missing. Full article

(This article belongs to the Special Issue Advances in Applications of Weather Radar Data)

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17 pages, 2807 KiB

Open AccessArticle

Evaluation of Moist Static Energy in a Simulated Tropical Cyclone

by Lijun Yu, Shuhui Wu and Zhanhong Ma

Atmosphere 2019, 10(6), 319; https://doi.org/10.3390/atmos10060319 - 12 Jun 2019

Cited by 5 | Viewed by 4826 | Correction

Abstract

The characteristics of moist static energy (MSE) and its budget in a simulated tropical cyclone (TC) are examined in this study. Results demonstrate that MSE in a TC system is enhanced as the storm strengthens, primarily because of two mechanisms: upward transfer of [...] Read more.

The characteristics of moist static energy (MSE) and its budget in a simulated tropical cyclone (TC) are examined in this study. Results demonstrate that MSE in a TC system is enhanced as the storm strengthens, primarily because of two mechanisms: upward transfer of surface heat fluxes and subsequent warming of the upper troposphere. An inspection of the interchangeable approximation between MSE and equivalent potential temperature (θ_e) suggests that although MSE is capable of capturing overall structures of θ_e, some important features will still be distorted, specifically the low-MSE pool outside the eyewall. In this low-MSE region, from the budget analysis, the discharge of MSE in the boundary layer may even surpass the recharge of MSE from the ocean. Unlike the volume-averaged MSE, the mass-weighted MSE in a fixed volume following the TC shows no apparent increase as the TC intensifies, because the atmosphere becomes continually thinner accompanying the warming of the storm. By calculating a mass-weighted volume MSE budget, the TC system is found to export MSE throughout its lifetime, since the radial outflow overwhelms the radial inflow. Moreover, the more intensified the TC is, the more export of MSE there tends to be. The input of MSE by surface heat fluxes is roughly balanced by the combined effects of radiation and lateral export, wherein a great majority of the imported MSE is reduced by radiation, while the export of MSE from the TC system to the environment accounts for only a small portion. Full article

(This article belongs to the Section Meteorology)

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