Pub Date : 2025-01-02DOI: 10.1016/j.atmosres.2024.107904
Enwang Luo, Guoxing Chen, Wei-Chyung Wang, Jie Feng, Yanhong Gao
This study conducted WRF simulations of Typhoon In-Fa (2021), which caused significant damage to the eastern China in 2021, to investigate how cloud vertical structure may affect the development of a tropical cyclone (TC). Specifically, the TC was simulated using two cloud-fraction schemes: the default Xu-Randall (XR) scheme and a newly-developed neural Network-based Scale-Adaptive (NSA) scheme. Results show that the NSA scheme simulates a more eastward TC track than the XR scheme for both the pre-landfall and landfall phases and is closer to the observation. The underlying mechanisms differ between the two phases and are closely associated with the TC asymmetric structure and phase evolution. First, the XR scheme simulates larger cloud fractions than the NSA scheme across the entire TC, yielding a stronger longwave cloud radiative effect (LWCRE). This tends to increase the instability and invigorates the convection. Second, the relatively strong convections in the northeast quadrant of the TC cause a horizontally-distributed cloud layer, where the NSA scheme simulates a less-tilted cloud structure and a more pronounced horizontal gradient of LWCRE, which can amplify the secondary circulation.
{"title":"Effects of cloud vertical structure on the development of tropical cyclones: A case study based on In-Fa (2021)","authors":"Enwang Luo, Guoxing Chen, Wei-Chyung Wang, Jie Feng, Yanhong Gao","doi":"10.1016/j.atmosres.2024.107904","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107904","url":null,"abstract":"This study conducted WRF simulations of Typhoon In-Fa (2021), which caused significant damage to the eastern China in 2021, to investigate how cloud vertical structure may affect the development of a tropical cyclone (TC). Specifically, the TC was simulated using two cloud-fraction schemes: the default Xu-Randall (XR) scheme and a newly-developed neural Network-based Scale-Adaptive (NSA) scheme. Results show that the NSA scheme simulates a more eastward TC track than the XR scheme for both the pre-landfall and landfall phases and is closer to the observation. The underlying mechanisms differ between the two phases and are closely associated with the TC asymmetric structure and phase evolution. First, the XR scheme simulates larger cloud fractions than the NSA scheme across the entire TC, yielding a stronger longwave cloud radiative effect (LWCRE). This tends to increase the instability and invigorates the convection. Second, the relatively strong convections in the northeast quadrant of the TC cause a horizontally-distributed cloud layer, where the NSA scheme simulates a less-tilted cloud structure and a more pronounced horizontal gradient of LWCRE, which can amplify the secondary circulation.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142918073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical prediction of warm-sector heavy precipitation under weak synoptic-scale forcing in South China remains a challenging problem. In this study, the simulation capabilities of four microphysics schemes (WSM6, Thompson, Thompson aerosol-aware, and Morrison) for the heavy rainfall event that occurred during 10–11 May 2022, which featured both a coastal warm-sector rain belt and an inland frontal rain belt, have been evaluated and improved by using polarimetric radar and 2DVDs. The results showed that four schemes effectively reproduced the coastal and inland heavy precipitation amounts but exhibited poor performance in describing raindrop size and number concentration, with noticeable differences among these schemes. Compared to observations, the microphysics schemes tended to produce raindrops with larger size and fewer number concentration. By incorporating the observed relationship between rainwater and generalized intercept parameter into the WSM6 scheme, the simulated raindrop size and number concentration were optimized with real-time diagnosis of raindrop intercept parameter. For the Thompson and Morrison double-moment schemes, modifying the diameter threshold parameter in raindrop self-collection process to enhance raindrop breakup efficiency was the most direct and effective method for improving simulation. Even though the impact of vertical wind shear on raindrop breakup was considered here, there remained a discrepancy between the simulated and observed raindrop sizes and number concentrations. Therefore, the reasons for adjusting this threshold parameter were still unclear. Additionally, using ECMWF-CAMS aerosol reanalysis data as input for Thompson aerosol-aware scheme showed a better representation of aerosol spatial distribution, thereby improving precipitation distribution, especially for the inland rain belt.
{"title":"Improvement of microphysics schemes for a warm-sector heavy precipitation over South China","authors":"Hui Xiao, Sheng Hu, Xiantong Liu, Huiqi Li, Songwei He, Lu Feng","doi":"10.1016/j.atmosres.2024.107905","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107905","url":null,"abstract":"Numerical prediction of warm-sector heavy precipitation under weak synoptic-scale forcing in South China remains a challenging problem. In this study, the simulation capabilities of four microphysics schemes (WSM6, Thompson, Thompson aerosol-aware, and Morrison) for the heavy rainfall event that occurred during 10–11 May 2022, which featured both a coastal warm-sector rain belt and an inland frontal rain belt, have been evaluated and improved by using polarimetric radar and 2DVDs. The results showed that four schemes effectively reproduced the coastal and inland heavy precipitation amounts but exhibited poor performance in describing raindrop size and number concentration, with noticeable differences among these schemes. Compared to observations, the microphysics schemes tended to produce raindrops with larger size and fewer number concentration. By incorporating the observed relationship between rainwater and generalized intercept parameter into the WSM6 scheme, the simulated raindrop size and number concentration were optimized with real-time diagnosis of raindrop intercept parameter. For the Thompson and Morrison double-moment schemes, modifying the diameter threshold parameter in raindrop self-collection process to enhance raindrop breakup efficiency was the most direct and effective method for improving simulation. Even though the impact of vertical wind shear on raindrop breakup was considered here, there remained a discrepancy between the simulated and observed raindrop sizes and number concentrations. Therefore, the reasons for adjusting this threshold parameter were still unclear. Additionally, using ECMWF-CAMS aerosol reanalysis data as input for Thompson aerosol-aware scheme showed a better representation of aerosol spatial distribution, thereby improving precipitation distribution, especially for the inland rain belt.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"20 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-31DOI: 10.1016/j.atmosres.2024.107901
Lu Ma, Shujuan Hu, Bingqian Zhou, Jianjun Peng, Deqian Li
The South Asian high (SAH) is an important circulation system that seriously affects the weather and climate over East Asia. Previous studies have proposed related indices based on geopotential height to monitor the intensity and movement of the SAH. However, the SAH indices defined by geopotential height have been questioned by some recent studies due to the overall enhancement of geopotential height in the context of climate warming. To objectively reflect the characteristics of SAH variability, we redefined the corresponding indices using the stream function R of horizontal circulation from the three-pattern decomposition of global atmospheric circulation (3P-DGAC) model and studied the interannual and interdecadal variations of SAH. The results indicate that from 1958 to 2023, the area index, intensity index, and eastward ridge point index exhibit significant interannual variability, while the interdecadal signals remain relatively constant. The ridge line index of SAH not only exhibits significant interannual variations but also shows a significant interdecadal movement. Before the late 1980s, the SAH ridge line shifted southward, while after the late 1980s, it shifted northward. Furthermore, the changing characteristics of the SAH defined by the stream function R more closely with those of relative vorticity and horizontal wind. The geopotential height presents a spurious interdecadal enhancement of SAH since 1990. The eddy geopotential height overestimates the interdecadal weakening of SAH around 1979. This shows that the stream function R provides a more objective and reliable representation of the interdecadal variations of the SAH compared to geopotential height and eddy geopotential height. Therefore, our study provides new research methods and index definitions for understanding the changing characteristics of SAH in the context of global warming, and it also gives important reference and methodological guidance for future relevant research.
{"title":"Novel dynamical indices for the variations of the South Asia high in a warming climate","authors":"Lu Ma, Shujuan Hu, Bingqian Zhou, Jianjun Peng, Deqian Li","doi":"10.1016/j.atmosres.2024.107901","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107901","url":null,"abstract":"The South Asian high (SAH) is an important circulation system that seriously affects the weather and climate over East Asia. Previous studies have proposed related indices based on geopotential height to monitor the intensity and movement of the SAH. However, the SAH indices defined by geopotential height have been questioned by some recent studies due to the overall enhancement of geopotential height in the context of climate warming. To objectively reflect the characteristics of SAH variability, we redefined the corresponding indices using the stream function <ce:italic>R</ce:italic> of horizontal circulation from the three-pattern decomposition of global atmospheric circulation (3P-DGAC) model and studied the interannual and interdecadal variations of SAH. The results indicate that from 1958 to 2023, the area index, intensity index, and eastward ridge point index exhibit significant interannual variability, while the interdecadal signals remain relatively constant. The ridge line index of SAH not only exhibits significant interannual variations but also shows a significant interdecadal movement. Before the late 1980s, the SAH ridge line shifted southward, while after the late 1980s, it shifted northward. Furthermore, the changing characteristics of the SAH defined by the stream function <ce:italic>R</ce:italic> more closely with those of relative vorticity and horizontal wind. The geopotential height presents a spurious interdecadal enhancement of SAH since 1990. The eddy geopotential height overestimates the interdecadal weakening of SAH around 1979. This shows that the stream function <ce:italic>R</ce:italic> provides a more objective and reliable representation of the interdecadal variations of the SAH compared to geopotential height and eddy geopotential height. Therefore, our study provides new research methods and index definitions for understanding the changing characteristics of SAH in the context of global warming, and it also gives important reference and methodological guidance for future relevant research.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"35 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-31DOI: 10.1016/j.atmosres.2024.107898
Juthi Rani Mitra, Kevin Czajkowski
Urban areas in Bangladesh have seen alarming levels of particulate matter for an extended period, posing serious threats to public health and economic stability. Particulate matter with a diameter of 2.5 μm or smaller, known as PM2.5, can be inhaled by humans and cause serious respiratory and cardiovascular health problems. This study revealed spatial and temporal patterns, seasonal and regional variations, hot spots, and cold spots of PM2.5 in Bangladesh. In addition, the relationship between PM2.5 and meteorological variables was investigated. The results indicate a positive spatial autocorrelation in PM2.5 concentrations, with recent hot spots primarily clustered in the Dhaka, and western parts of the Chittagong divisions. In contrast, cold spots are observed in the Sylhet, Rangpur, and eastern parts of the Chittagong divisions. Seasonal variations revealed notably high PM2.5 concentrations during the winter season. Furthermore, annual average PM2.5 concentrations showed increasing trends for most divisions in Bangladesh, particularly elevated concentrations in Dhaka, Barisal, Khulna, and Chittagong. Overall, this study provides a comprehensive analysis of PM2.5 spatial distributions, clusters, and temporal patterns contributing to understanding the variation and distribution of PM2.5 concentrations across Bangladesh. The findings of this study can be applied to urban planning by prioritizing areas for new air quality monitoring stations, directing efforts to reduce pollution in hot spot areas, and formulating long-term, source-specific policies to improve air quality and public health.
{"title":"Spatiotemporal patterns and hot spots of PM2.5 in Bangladesh","authors":"Juthi Rani Mitra, Kevin Czajkowski","doi":"10.1016/j.atmosres.2024.107898","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107898","url":null,"abstract":"Urban areas in Bangladesh have seen alarming levels of particulate matter for an extended period, posing serious threats to public health and economic stability. Particulate matter with a diameter of 2.5 μm or smaller, known as PM<ce:inf loc=\"post\">2.5</ce:inf>, can be inhaled by humans and cause serious respiratory and cardiovascular health problems. This study revealed spatial and temporal patterns, seasonal and regional variations, hot spots, and cold spots of PM<ce:inf loc=\"post\">2.5</ce:inf> in Bangladesh. In addition, the relationship between PM<ce:inf loc=\"post\">2.5</ce:inf> and meteorological variables was investigated. The results indicate a positive spatial autocorrelation in PM<ce:inf loc=\"post\">2.5</ce:inf> concentrations, with recent hot spots primarily clustered in the Dhaka, and western parts of the Chittagong divisions. In contrast, cold spots are observed in the Sylhet, Rangpur, and eastern parts of the Chittagong divisions. Seasonal variations revealed notably high PM<ce:inf loc=\"post\">2.5</ce:inf> concentrations during the winter season. Furthermore, annual average PM<ce:inf loc=\"post\">2.5</ce:inf> concentrations showed increasing trends for most divisions in Bangladesh, particularly elevated concentrations in Dhaka, Barisal, Khulna, and Chittagong. Overall, this study provides a comprehensive analysis of PM<ce:inf loc=\"post\">2.5</ce:inf> spatial distributions, clusters, and temporal patterns contributing to understanding the variation and distribution of PM<ce:inf loc=\"post\">2.5</ce:inf> concentrations across Bangladesh. The findings of this study can be applied to urban planning by prioritizing areas for new air quality monitoring stations, directing efforts to reduce pollution in hot spot areas, and formulating long-term, source-specific policies to improve air quality and public health.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The 2020 Meiyu season in Anhui, China, brought unprecedented rainfall, driven by a unique interplay of high precipitation frequency and elevated convective rainfall. This study examines the distinctive microphysical characteristics of raindrop size distribution (DSD) during this record-breaking season, using minute-level data from six disdrometer stations. Brief but intense rain events contributed up to 49.4 % of the total seasonal rainfall in only 6–7 % of the duration, with the mean drop diameter increasing from 1.2 mm to 2.1 mm and the mean normalized intercept parameter rising from 2.7 to 4.1 as rainfall rate intensified. Compared to prior Meiyu studies, our findings reveal distinct DSD patterns with larger raindrops and higher concentrations, reflecting a more convective-dominated structure unique to the 2020 season. Novel μ–Λ and Z − R relationships tailored for this event revealed larger raindrop sizes and concentrations compared to past studies. Enhanced dual-polarization radar rainfall prediction models were developed, with relationships between Zdr, Zh, Kdp, and rainfall rate (R) showing exceptional accuracy, as evidenced by correlation coefficients nearing 1.0 and low RMSE and NMAE values. Additionally, new KE–R relationships accurately estimated rainfall kinetic energy (KE), with Power Law models best representing KEtime–R and Logarithmic fits for KEmm–R. These findings demonstrate the importance of DSD-specific insights for understanding microphysical processes and improving QPE accuracy, with implications for flood and soil erosion management in eastern China.
{"title":"Microphysical characteristics of the 2020 record-breaking Meiyu rainfall in Anhui, China","authors":"Qiqi Yang, Shuliang Zhang, Yiheng Chen, Yuhan Jin, Hongyuan Fang","doi":"10.1016/j.atmosres.2024.107900","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107900","url":null,"abstract":"The 2020 Meiyu season in Anhui, China, brought unprecedented rainfall, driven by a unique interplay of high precipitation frequency and elevated convective rainfall. This study examines the distinctive microphysical characteristics of raindrop size distribution (DSD) during this record-breaking season, using minute-level data from six disdrometer stations. Brief but intense rain events contributed up to 49.4 % of the total seasonal rainfall in only 6–7 % of the duration, with the mean drop diameter increasing from 1.2 mm to 2.1 mm and the mean normalized intercept parameter rising from 2.7 to 4.1 as rainfall rate intensified. Compared to prior Meiyu studies, our findings reveal distinct DSD patterns with larger raindrops and higher concentrations, reflecting a more convective-dominated structure unique to the 2020 season. Novel <ce:italic>μ</ce:italic>–<ce:italic>Λ</ce:italic> and <ce:italic>Z</ce:italic> − <ce:italic>R</ce:italic> relationships tailored for this event revealed larger raindrop sizes and concentrations compared to past studies. Enhanced dual-polarization radar rainfall prediction models were developed, with relationships between <mml:math altimg=\"si15.svg\"><mml:msub><mml:mi>Z</mml:mi><mml:mi mathvariant=\"italic\">dr</mml:mi></mml:msub></mml:math>, <mml:math altimg=\"si14.svg\"><mml:msub><mml:mi>Z</mml:mi><mml:mi>h</mml:mi></mml:msub></mml:math>, <mml:math altimg=\"si16.svg\"><mml:msub><mml:mi>K</mml:mi><mml:mi mathvariant=\"italic\">dp</mml:mi></mml:msub></mml:math>, and rainfall rate (<ce:italic>R</ce:italic>) showing exceptional accuracy, as evidenced by correlation coefficients nearing 1.0 and low RMSE and NMAE values. Additionally, new <ce:italic>KE</ce:italic>–<ce:italic>R</ce:italic> relationships accurately estimated rainfall kinetic energy (<ce:italic>KE</ce:italic>), with Power Law models best representing <mml:math altimg=\"si18.svg\"><mml:msub><mml:mi mathvariant=\"italic\">KE</mml:mi><mml:mi mathvariant=\"italic\">time</mml:mi></mml:msub></mml:math>–<ce:italic>R</ce:italic> and Logarithmic fits for <mml:math altimg=\"si19.svg\"><mml:msub><mml:mi mathvariant=\"italic\">KE</mml:mi><mml:mi mathvariant=\"italic\">mm</mml:mi></mml:msub></mml:math>–<ce:italic>R</ce:italic>. These findings demonstrate the importance of DSD-specific insights for understanding microphysical processes and improving QPE accuracy, with implications for flood and soil erosion management in eastern China.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142918079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-31DOI: 10.1016/j.atmosres.2024.107899
Emilio Martínez-Ibarra, Francisco Javier Bello-Millán, Juan Garrido-Clavero
This paper analyses and characterizes snowfall events in one of the hottest, most arid areas in continental Europe. Our information was taken from a snowfall database that was partly our own, covering a period of over 100 years. The FLEXTRA model of air-mass back-trajectories was applied together with our own subjective synoptic classification. Data from the ECMWF Reanalysis of the 20th Century (ERA20C) were used for the calculation and clustering of the back-trajectories and the establishment of synoptic weather types. The snowfall events were classified into 8 synoptic types and 4 first-level and 8 s-level back-trajectories. The meteorological scenario for these extreme events was marked by mixed structures at altitude with a main NE/SW axis and dipoles on the surface dominated by powerful North Atlantic anti-cyclones and back-trajectories from the NE at the three levels analysed (500, 1500 and 5000 m.a.s.l.).
{"title":"Air-mass trajectories and extreme episodes: Snowfalls on the natural region of the south-east coast of the Iberian Peninsula (1900–2005)","authors":"Emilio Martínez-Ibarra, Francisco Javier Bello-Millán, Juan Garrido-Clavero","doi":"10.1016/j.atmosres.2024.107899","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107899","url":null,"abstract":"This paper analyses and characterizes snowfall events in one of the hottest, most arid areas in continental Europe. Our information was taken from a snowfall database that was partly our own, covering a period of over 100 years. The FLEXTRA model of air-mass back-trajectories was applied together with our own subjective synoptic classification. Data from the ECMWF Reanalysis of the 20th Century (ERA<ce:glyph name=\"sbnd\"></ce:glyph>20C) were used for the calculation and clustering of the back-trajectories and the establishment of synoptic weather types. The snowfall events were classified into 8 synoptic types and 4 first-level and 8 s-level back-trajectories. The meteorological scenario for these extreme events was marked by mixed structures at altitude with a main NE/SW axis and dipoles on the surface dominated by powerful North Atlantic anti-cyclones and back-trajectories from the NE at the three levels analysed (500, 1500 and 5000 m.a.s.l.).","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"11 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142918080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Yunnan-Guizhou quasi-stationary front significantly influences winter weather in the Yungui Plateau (YGP), bringing low temperature, sharp cooling, and regional precipitation. This study objectively identifies fronts and quantitatively characterizes them in terms of location, orientation, length, intensity, and movement. Furthermore, the three-dimensional circulation and local weather impact for different types are analyzed. From 1971 to 2020, a total of 5125 frontal days were identified. The frontal frequency exhibits a sector-shaped pattern, with its maximum frequency over the northwestern part of the YGP, and five high-frequency belts distribute from the northeast to west. Five front types (C1 to C5; from east to west) anchor over the steep terrain on the YGP. C1 to C3 fronts are northwest-southeast-oriented, and C4 fronts are north-south-oriented, while C5 is northeast-southwest-oriented. East of the fronts, the near-surface northeasterly wind carrying colder air is blocked by the steep terrain and veers upward over the eastern slope. The southwesterly winds west of the fronts transport warmer air above near-surface colder air, forming an inversion layer. In C1 and C2, weak cold air remains north of 25°N, while strong southwesterly flow extends into the eastern lowlands. This causes fronts positioned more eastwardly, with both low-level inversion and the extensive high-frequency precipitation to the east of the fronts. In C4 and C5, strong cold air intrusion into the YGP causes fronts positioned further west. Inversion and high-frequency precipitation concentrate at higher elevations in the western YGP. Quantifying the refined frontal features is crucial for enhancing the accuracy of local weather forecasting.
{"title":"Quantitative characteristics of the quasi-stationary front anchored over the steep terrain on the Yungui Plateau","authors":"Ni Gao, Jian Li, Rucong Yu, Nina Li, Jiawei Zhang, Yin Zhao","doi":"10.1016/j.atmosres.2024.107902","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107902","url":null,"abstract":"The Yunnan-Guizhou quasi-stationary front significantly influences winter weather in the Yungui Plateau (YGP), bringing low temperature, sharp cooling, and regional precipitation. This study objectively identifies fronts and quantitatively characterizes them in terms of location, orientation, length, intensity, and movement. Furthermore, the three-dimensional circulation and local weather impact for different types are analyzed. From 1971 to 2020, a total of 5125 frontal days were identified. The frontal frequency exhibits a sector-shaped pattern, with its maximum frequency over the northwestern part of the YGP, and five high-frequency belts distribute from the northeast to west. Five front types (C1 to C5; from east to west) anchor over the steep terrain on the YGP. C1 to C3 fronts are northwest-southeast-oriented, and C4 fronts are north-south-oriented, while C5 is northeast-southwest-oriented. East of the fronts, the near-surface northeasterly wind carrying colder air is blocked by the steep terrain and veers upward over the eastern slope. The southwesterly winds west of the fronts transport warmer air above near-surface colder air, forming an inversion layer. In C1 and C2, weak cold air remains north of 25°N, while strong southwesterly flow extends into the eastern lowlands. This causes fronts positioned more eastwardly, with both low-level inversion and the extensive high-frequency precipitation to the east of the fronts. In C4 and C5, strong cold air intrusion into the YGP causes fronts positioned further west. Inversion and high-frequency precipitation concentrate at higher elevations in the western YGP. Quantifying the refined frontal features is crucial for enhancing the accuracy of local weather forecasting.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"118 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Detailed characterization of the planetary boundary layer (PBL) and mixing layer height (MLH) is essential for gaining insights into air quality, pollutant dispersion, and the dynamics of the lower atmosphere. This research involves MLH from four atmospheric models—ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5), Reanalysis, GDAS (Global Data Assimilation System), and GFS (Global Forecast System), representing diverse approaches commonly applied in atmospheric research, mainly in air quality studies. The intercomparison analyzes the simulated MLH from the models, comparing them with observations from radiosondes and ceilometers to capture diurnal and seasonal variations in boundary layer dynamics. The study reveals significant diurnal and seasonal variations, with a close alignment between ERA5 boundary layer and ceilometer mixing layer observations, Reanalysis consistently underestimating MLH altitude, and both GFS and GDAS models demonstrating reasonable diurnal cycles of MLH. During summer, all models underestimate MLH compared to ceilometer observations by 34–42 %, while in winter, overestimation relative to ceilometer observations ranges from 11 to 20 %. Factors contributing to this discrepancy, including meteorological variables and synoptic situations, were examined. GFS and GDAS tend to overestimate global radiation after 12:00 but underestimate MLH, while ERA5 consistently underestimated both radiation and MLH. Dependence in agreement between models and ceilometer observations was also observed for various synoptic situations. The interconnected nature of atmospheric stability and turbulence, highlighted by Richardson number analysis, further emphasizes the importance of understanding turbulence patterns for accurate MLH predictions.
{"title":"Boundary layer and mixing layer height: Models vs. Ground-based measurements intercomparison","authors":"Kajal Julaha, Vladimír Ždímal, Adéla Holubová Šmejkalová, Kateřina Komínková, Naděžda Zíková","doi":"10.1016/j.atmosres.2024.107897","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107897","url":null,"abstract":"Detailed characterization of the planetary boundary layer (PBL) and mixing layer height (MLH) is essential for gaining insights into air quality, pollutant dispersion, and the dynamics of the lower atmosphere. This research involves MLH from four atmospheric models—ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5), Reanalysis, GDAS (Global Data Assimilation System), and GFS (Global Forecast System), representing diverse approaches commonly applied in atmospheric research, mainly in air quality studies. The intercomparison analyzes the simulated MLH from the models, comparing them with observations from radiosondes and ceilometers to capture diurnal and seasonal variations in boundary layer dynamics. The study reveals significant diurnal and seasonal variations, with a close alignment between ERA5 boundary layer and ceilometer mixing layer observations, Reanalysis consistently underestimating MLH altitude, and both GFS and GDAS models demonstrating reasonable diurnal cycles of MLH. During summer, all models underestimate MLH compared to ceilometer observations by 34–42 %, while in winter, overestimation relative to ceilometer observations ranges from 11 to 20 %. Factors contributing to this discrepancy, including meteorological variables and synoptic situations, were examined. GFS and GDAS tend to overestimate global radiation after 12:00 but underestimate MLH, while ERA5 consistently underestimated both radiation and MLH. Dependence in agreement between models and ceilometer observations was also observed for various synoptic situations. The interconnected nature of atmospheric stability and turbulence, highlighted by Richardson number analysis, further emphasizes the importance of understanding turbulence patterns for accurate MLH predictions.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142918086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-28DOI: 10.1016/j.atmosres.2024.107896
Xi Chen, Dabang Jiang, Hao Fan, Yuan Liu, Chengfang Huang
Extreme temperature events are the primary factors contributing to human morbidity and mortality related to climate change. However, there is limited understanding of changes in past and future human-perceived temperature (HPT) extremes evaluated in a consistent manner. Building upon the traditional framework of using relative thresholds to define temperature extremes, we further introduce the absolute threshold constraint of human thermal comfort indices, which allows us to capture extreme HPT events that do have the potential to threaten human health. Based on daily observations and model outputs from the Coupled Model Intercomparison Project phase 6 (CMIP6), we investigate the climatology and long-term change in the frequency of summer heat extremes (conditions of high temperatures and humidity) and winter cold extremes (conditions of cold temperatures and winds) across China. The associated population exposure is also quantified. Results show a substantial increase in heat extremes along the coast of Southeast China and parts of Northwest China, as well as a significant decrease in cold extremes over northern China and the Tibetan Plateau from 1961 to 2014. CMIP6 models project that China will confront an elevating risk of extreme heat stress and a decreasing threat of extreme cold events in the future period. South China and Jianghuai are expected to experience the largest increases of population exposure to extreme heat days, and the greatest decreases of cold exposure are located in North China and Jianghuai. Our findings indicate that opposite conclusions regarding the trend in the frequency of HPT extremes might be drawn with and without the absolute threshold constraint of human thermal comfort indices, as well as the use of different absolute thresholds.
{"title":"Changes in human-perceived temperature extremes and associated population exposure across China","authors":"Xi Chen, Dabang Jiang, Hao Fan, Yuan Liu, Chengfang Huang","doi":"10.1016/j.atmosres.2024.107896","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107896","url":null,"abstract":"Extreme temperature events are the primary factors contributing to human morbidity and mortality related to climate change. However, there is limited understanding of changes in past and future human-perceived temperature (HPT) extremes evaluated in a consistent manner. Building upon the traditional framework of using relative thresholds to define temperature extremes, we further introduce the absolute threshold constraint of human thermal comfort indices, which allows us to capture extreme HPT events that do have the potential to threaten human health. Based on daily observations and model outputs from the Coupled Model Intercomparison Project phase 6 (CMIP6), we investigate the climatology and long-term change in the frequency of summer heat extremes (conditions of high temperatures and humidity) and winter cold extremes (conditions of cold temperatures and winds) across China. The associated population exposure is also quantified. Results show a substantial increase in heat extremes along the coast of Southeast China and parts of Northwest China, as well as a significant decrease in cold extremes over northern China and the Tibetan Plateau from 1961 to 2014. CMIP6 models project that China will confront an elevating risk of extreme heat stress and a decreasing threat of extreme cold events in the future period. South China and Jianghuai are expected to experience the largest increases of population exposure to extreme heat days, and the greatest decreases of cold exposure are located in North China and Jianghuai. Our findings indicate that opposite conclusions regarding the trend in the frequency of HPT extremes might be drawn with and without the absolute threshold constraint of human thermal comfort indices, as well as the use of different absolute thresholds.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"55 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142917982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-26DOI: 10.1016/j.atmosres.2024.107894
Amit Kumar, Atul Kumar Srivastava, Bharat Ji Mehrotra, Manoj Kumar Srivastava, D.R. Pattanaik
Global Precipitation Measurement satellite equipped with space-borne dual-frequency precipitation radar (GPM-DPR) allows to investigate the precipitating cloud microphysics and precipitation structures, irrespective of the terrain's ruggedness. Ten years (from March 2014 to December 2023) of continuous GPM-DPR level2 V07A data is processed to understand the decadal changes in precipitation microphysics across the Western Ghats (8°N-20°N and 73°E-77°E) during the monsoon season including before onset (pre-monsoon) and withdrawal (post-monsoon) periods. The spatial distribution of rain rate (R: mm/h), mass-weighted mean diameter (Dm: mm), and normalized intercept parameters (Nw: m−3 mm−1) shows considerable variations depending on cloud types and seasons. During the stratiform precipitation, low-intensity rainfall dominates, characterized by low Dm and high Nw, indicating a significant concentration of smaller raindrops. In contrast, the escalation of high-intensity rainfall due to increased convective activity and strong updrafts during the convective precipitation causes the enlargement of raindrops, augments the concentration of bigger raindrops. Dm-Nw joint histogram displayed distinguishable patterns; range and peak varied with the cloud type and season. It may result from differences in the occurrence rate of various microphysical processes. The share of collision-coalescences process is a maximum of 72.35 % for the convective precipitation in the monsoon season. At the same time, the highest break-up process contribution is 52.05 % during stratiform rainfall of the post-monsoon season.
{"title":"Decadal seasonal characteristics of precipitation microphysics over the Western Ghats using the space-borne precipitation radar","authors":"Amit Kumar, Atul Kumar Srivastava, Bharat Ji Mehrotra, Manoj Kumar Srivastava, D.R. Pattanaik","doi":"10.1016/j.atmosres.2024.107894","DOIUrl":"https://doi.org/10.1016/j.atmosres.2024.107894","url":null,"abstract":"Global Precipitation Measurement satellite equipped with space-borne dual-frequency precipitation radar (GPM-DPR) allows to investigate the precipitating cloud microphysics and precipitation structures, irrespective of the terrain's ruggedness. Ten years (from March 2014 to December 2023) of continuous GPM-DPR level2 V07A data is processed to understand the decadal changes in precipitation microphysics across the Western Ghats (8°N-20°N and 73°E-77°E) during the monsoon season including before onset (pre-monsoon) and withdrawal (post-monsoon) periods. The spatial distribution of rain rate (R: mm/h), mass-weighted mean diameter (D<ce:inf loc=\"post\">m</ce:inf>: mm), and normalized intercept parameters (N<ce:inf loc=\"post\">w</ce:inf>: m<ce:sup loc=\"post\">−3</ce:sup> mm<ce:sup loc=\"post\">−1</ce:sup>) shows considerable variations depending on cloud types and seasons. During the stratiform precipitation, low-intensity rainfall dominates, characterized by low D<ce:inf loc=\"post\">m</ce:inf> and high N<ce:inf loc=\"post\">w</ce:inf>, indicating a significant concentration of smaller raindrops. In contrast, the escalation of high-intensity rainfall due to increased convective activity and strong updrafts during the convective precipitation causes the enlargement of raindrops, augments the concentration of bigger raindrops. D<ce:inf loc=\"post\">m</ce:inf>-N<ce:inf loc=\"post\">w</ce:inf> joint histogram displayed distinguishable patterns; range and peak varied with the cloud type and season. It may result from differences in the occurrence rate of various microphysical processes. The share of collision-coalescences process is a maximum of 72.35 % for the convective precipitation in the monsoon season. At the same time, the highest break-up process contribution is 52.05 % during stratiform rainfall of the post-monsoon season.","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"27 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142917985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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