Pub Date : 2025-03-01DOI: 10.1016/j.aosl.2024.100480
Yue Dong , Qingqing Li
A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Henan Province, China, on 20 July 2021. The simulation results showed that a strong meso-γ-scale vortical updraft was concurrent with the torrential rainfall. The main finding is that this event was characterized by typical midlatitude warm-rain processes. The simulation with the Thompson microphysics scheme further indicated that highly efficient collision–coalescence of cloud water to rainwater resulted in a considerably active rain droplet growth, leading to this record-breaking rainfall event.
A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Henan Province, China, on 20 July 2021. The simulation results showed that a strong meso-γ-scale vortical updraft was concurrent with the torrential rainfall. The main finding is that this event was characterized by typical midlatitude warm-rain processes. The simulation with the Thompson microphysics scheme further indicated that highly efficient collision–coalescence of cloud water to rainwater resulted in a considerably active rain droplet growth, leading to this record-breaking rainfall event.摘要对2021年7月20日发生在河南郑州的一次极端降水事件进行了数值模拟. 模拟结果显示强烈的中-γ尺度旋转上升运动与极端降水同时出现. 研究进一步指出该极端降水事件表现为典型的中纬度暖雨降水过程, 基于Thompson方案的水凝物粒子混合比收支诊断结果表明这次极端降水事件主要由高效的碰并增长过程导致.
{"title":"Microphysical processes of the “21·7” Henan extremely heavy rainfall event as simulated with the Thompson microphysics scheme","authors":"Yue Dong , Qingqing Li","doi":"10.1016/j.aosl.2024.100480","DOIUrl":"10.1016/j.aosl.2024.100480","url":null,"abstract":"<div><div>A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Henan Province, China, on 20 July 2021. The simulation results showed that a strong meso-<em>γ</em>-scale vortical updraft was concurrent with the torrential rainfall. The main finding is that this event was characterized by typical midlatitude warm-rain processes. The simulation with the Thompson microphysics scheme further indicated that highly efficient collision–coalescence of cloud water to rainwater resulted in a considerably active rain droplet growth, leading to this record-breaking rainfall event.</div><div>摘要</div><div>对2021年7月20日发生在河南郑州的一次极端降水事件进行了数值模拟. 模拟结果显示强烈的中-γ尺度旋转上升运动与极端降水同时出现. 研究进一步指出该极端降水事件表现为典型的中纬度暖雨降水过程, 基于Thompson方案的水凝物粒子混合比收支诊断结果表明这次极端降水事件主要由高效的碰并增长过程导致.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 2","pages":"Article 100480"},"PeriodicalIF":2.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139828059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.aosl.2025.100610
Xinli Liu , Jingzhi Su , Yihao Peng , Xiaolei Liu
Subseasonal forecasting of extreme events is crucial for early warning systems. However, the forecast skills for extreme events are limited. Taking the extreme cold events in January 2018 as a specific example, and analyzing the 34 extreme cold events in East Asia from 1998 to 2020, the authors evaluated the forecast skills of the ECMWF model ensemble members on subseasonal time scales. The results show that while the ensemble mean has limited skills for forecasting extreme cold events at the 3-week lead time, some individual members demonstrate high forecast skills. For most extreme cold events, there are >10 % of members among the total ensembles that can well predict the rapid temperature transitions at the 14-day lead time. This highlights the untapped potential of the ECMWF model to forecast extreme cold events on subseasonal time scales. High-skill ensemble members rely on accurate predictions of atmospheric circulation patterns (500-hPa geopotential height, mean sea level pressure) and key weather systems, including the Ural Blocking and Siberian High, that influence extreme cold events.
{"title":"High-skill members in the subseasonal forecast ensemble of extreme cold events in East Asia","authors":"Xinli Liu , Jingzhi Su , Yihao Peng , Xiaolei Liu","doi":"10.1016/j.aosl.2025.100610","DOIUrl":"10.1016/j.aosl.2025.100610","url":null,"abstract":"<div><div>Subseasonal forecasting of extreme events is crucial for early warning systems. However, the forecast skills for extreme events are limited. Taking the extreme cold events in January 2018 as a specific example, and analyzing the 34 extreme cold events in East Asia from 1998 to 2020, the authors evaluated the forecast skills of the ECMWF model ensemble members on subseasonal time scales. The results show that while the ensemble mean has limited skills for forecasting extreme cold events at the 3-week lead time, some individual members demonstrate high forecast skills. For most extreme cold events, there are >10 % of members among the total ensembles that can well predict the rapid temperature transitions at the 14-day lead time. This highlights the untapped potential of the ECMWF model to forecast extreme cold events on subseasonal time scales. High-skill ensemble members rely on accurate predictions of atmospheric circulation patterns (500-hPa geopotential height, mean sea level pressure) and key weather systems, including the Ural Blocking and Siberian High, that influence extreme cold events.</div><div>摘要</div><div>极端事件次季节预报对防灾减灾保障社会经济安全具有重要意义. 本研究针对东亚地区极端低温事件的次季节预报难题, 通过分析1998–2020年34起东亚地区极端低温事件, 并重点关注2018年1月中国东北地区极端低温事件, 系统评估不同版本ECMWF模式集合成员之间的预报性能. 提前3周的模式集合平均预报性能存在局限, 但不同集合成员的预报技巧存在差异. 部分成员具有高预报技巧, 约10 %的高技巧成员能提前14天捕捉气温快速转折的过程. 研究指出集合成员是否具有高预报技巧依赖于对大气环流演变特征的合理预报. 该发现为极端冷事件次季节预报评估和后期订正提供了新视角, 凸显挖掘集合成员预报潜力的重要性, 并为提升次季节时间尺度预警能力提供了理论支撑.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100610"},"PeriodicalIF":3.2,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-02-27DOI: 10.1016/j.aosl.2025.100609
Yuting Ma , Xinyong Shen , Liang Zhao , Zijia Wang , Huibin Wang , Yihui Ding , Jingsong Wang , Yanju Liu , Cunrui Huang
Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events. However, the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives, without integrating health data, making the conclusions less practical for guiding health risk prevention. This study identified the threshold for hot–dry compound extreme events with high mortality risks (HMHDs) in China, using daily mortality data and temperature–humidity data from 278 districts or counties, and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021. The results show a significant increase in annual HMHD frequency in China after 2000, mainly occurring in summer (June, July, August). The northwestern to western regions of China (Xinjiang, Inner Mongolia, Gansu), and from the southwestern to the areas south of the Yangtze River (Sichuan, Hubei, Hunan, Jiangxi, Fujian, Guizhou, Yunnan), experience an increase of >10 days. The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.
{"title":"The increase in hot–dry events with a high risk of mortality in China associated with the phase transition of the Atlantic Multidecadal Oscillation","authors":"Yuting Ma , Xinyong Shen , Liang Zhao , Zijia Wang , Huibin Wang , Yihui Ding , Jingsong Wang , Yanju Liu , Cunrui Huang","doi":"10.1016/j.aosl.2025.100609","DOIUrl":"10.1016/j.aosl.2025.100609","url":null,"abstract":"<div><div>Compound extreme climate events involving multiple meteorological elements usually have a more severe impact on the environment and human health than single-element extreme events. However, the current definition of multi-element compound extreme events is proposed from meteorological and statistical perspectives, without integrating health data, making the conclusions less practical for guiding health risk prevention. This study identified the threshold for hot–dry compound extreme events with high mortality risks (HMHDs) in China, using daily mortality data and temperature–humidity data from 278 districts or counties, and explored the interdecadal change and driving mechanisms of HMHD frequency in China from 1979 to 2021. The results show a significant increase in annual HMHD frequency in China after 2000, mainly occurring in summer (June, July, August). The northwestern to western regions of China (Xinjiang, Inner Mongolia, Gansu), and from the southwestern to the areas south of the Yangtze River (Sichuan, Hubei, Hunan, Jiangxi, Fujian, Guizhou, Yunnan), experience an increase of >10 days. The authors find that the interdecadal abrupt change in HMHD frequency can be attributed to the shift of the Atlantic Multidecadal Oscillation from a negative to a positive phase by affecting the Silk Road teleconnection.</div><div>摘要</div><div>目前对复合极端事件的定义主要从气象和统计学角度出发, 未能结合健康数据, 使相关研究在指导健康风险预防方面的实用性较差. 本研究利用中国死亡数据和温湿度数据, 识别了中国高死亡风险的复合极端干热事件 (HMHDs) 的阈值, 并探讨了HMHD频率的年代际变化及其驱动机制. 结果显示, 中国西北地区, 西南地区和江南地区的HMHD频率平均每年都超过10 天. 2000年后, 中国HMHD频率显著增加, 主要发生在夏季. 驱动机制分析表明, HMHD频率的年代际变化可以归因于大西洋多年代际振荡由负相位转变为正相位. 本研究可为气候变化导致的健康风险防控提供参考依据.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 4","pages":"Article 100609"},"PeriodicalIF":2.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-02-20DOI: 10.1016/j.aosl.2025.100606
Yuhao Lin , Chunsong Lu , Yunying Li , Ru Zhou
Cloud type profoundly affects precipitation, but few studies have explored its impact on precipitation scale height. The authors calculated the ratio of the volume of each cloud type to the total cloud volume and partitioned the tropical region based on the dominant cloud types. Based on this, tropical regions were categorized into altocumulus control regions, stratocumulus control regions, deep convective cloud control regions, and transition regions. These regions exhibit unique characteristics: high precipitation scale heights and low surface precipitation rates in altocumulus control regions; low precipitation scale heights and low surface precipitation rates in stratocumulus control regions; and moderate precipitation scale heights with high surface precipitation rates in deep convective cloud regions. These features arise from differences in cloud characteristics, precipitation probability, and intensity, influenced by varying water vapor structures. In terms of physical mechanisms, altocumulus, stratocumulus, and deep convective cloud regions are characterized by total dryness, upper-level dryness with lower-level wetness, and total wetness, respectively. Upper-layer dryness leads to low cloud and precipitation structures, reducing the precipitation scale height, while lower-layer dryness increases it. Different humidity conditions in the upper and lower layers lead to variations in cloud type and volume distribution, ultimately affecting precipitation scale heights. This finding aids the mechanistic study of cloud precipitation physics in the tropics, providing valuable insights for developing numerical models and parameterizations.
{"title":"A new approach for identifying dominant cloud types and relationships between cloud types and precipitation vertical structure in tropical regions","authors":"Yuhao Lin , Chunsong Lu , Yunying Li , Ru Zhou","doi":"10.1016/j.aosl.2025.100606","DOIUrl":"10.1016/j.aosl.2025.100606","url":null,"abstract":"<div><div>Cloud type profoundly affects precipitation, but few studies have explored its impact on precipitation scale height. The authors calculated the ratio of the volume of each cloud type to the total cloud volume and partitioned the tropical region based on the dominant cloud types. Based on this, tropical regions were categorized into altocumulus control regions, stratocumulus control regions, deep convective cloud control regions, and transition regions. These regions exhibit unique characteristics: high precipitation scale heights and low surface precipitation rates in altocumulus control regions; low precipitation scale heights and low surface precipitation rates in stratocumulus control regions; and moderate precipitation scale heights with high surface precipitation rates in deep convective cloud regions. These features arise from differences in cloud characteristics, precipitation probability, and intensity, influenced by varying water vapor structures. In terms of physical mechanisms, altocumulus, stratocumulus, and deep convective cloud regions are characterized by total dryness, upper-level dryness with lower-level wetness, and total wetness, respectively. Upper-layer dryness leads to low cloud and precipitation structures, reducing the precipitation scale height, while lower-layer dryness increases it. Different humidity conditions in the upper and lower layers lead to variations in cloud type and volume distribution, ultimately affecting precipitation scale heights. This finding aids the mechanistic study of cloud precipitation physics in the tropics, providing valuable insights for developing numerical models and parameterizations.</div><div>摘要</div><div>云类型对降水有重要影响, 但其对降水尺度高度的作用研究尚少. 本研究通过计算各云类型体积占总云体积的比例, 将热带地区划分为高积云, 层积云, 深对流云控制区及过渡区. 高积云区降水尺度高度较高, 地表降水率较低; 层积云区降水尺度高度和地表降水率均较低; 深对流云区降水尺度高度适中, 地表降水率较高. 这些特征由云特性, 降水概率和强度的差异决定, 并受到水汽结构的影响. 高积云, 层积云和深对流云区分别表现为整体干燥, 上层干燥且下层湿润, 以及整体湿润的特征. 上层干燥降低降水尺度高度, 下层干燥则升高高度. 上下层湿度差异影响云类型分布和降水结构, 最终决定降水尺度高度. 本研究为云降水物理机制研究及数值模式开发提供了新视角.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100606"},"PeriodicalIF":3.2,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-02-15DOI: 10.1016/j.aosl.2025.100597
Yonghang Hu, Xu Yue, Chenguang Tian
The El Niño–Southern Oscillation (ENSO) is a key driver of global climate variability, profoundly influencing regional fire activities and associated pollutant emissions. This study investigates the impacts of ENSO on global fire emissions and fire-induced PM2.5 concentrations in 2000–2023. During El Niño events, global fire emissions increase by 5.9 %–20.0 % with regional hotspots in Indonesia, North America, and Australia, driven by anomalous warming and rainfall deficits. In contrast, La Niña events result in a 3.2 %–9.9 % reduction in global fire emissions, with regional variability depending on the fire inventories used. In response, fire-induced PM2.5 concentrations increase substantially during El Niño, rising by 27.5 %–71.0 % in Indonesia, 49.2 %–116.5 % in North America, and 17.5 %–42.6 % in Australia. Conversely, La Niña events lead to decreases of 26.6 %–52.5 %, 19.4 %–37.3 %, 14.5 %–24.4 % in these regions, respectively. These findings highlight the critical role of ENSO in shaping fire emissions and air pollution from regional to global scales, providing valuable insights for mitigating the impacts of climatic extremes on air quality.
{"title":"Impacts of El Niño–Southern Oscillation on global fire PM2.5 during 2000–2023","authors":"Yonghang Hu, Xu Yue, Chenguang Tian","doi":"10.1016/j.aosl.2025.100597","DOIUrl":"10.1016/j.aosl.2025.100597","url":null,"abstract":"<div><div>The El Niño–Southern Oscillation (ENSO) is a key driver of global climate variability, profoundly influencing regional fire activities and associated pollutant emissions. This study investigates the impacts of ENSO on global fire emissions and fire-induced PM<sub>2.5</sub> concentrations in 2000–2023. During El Niño events, global fire emissions increase by 5.9 %–20.0 % with regional hotspots in Indonesia, North America, and Australia, driven by anomalous warming and rainfall deficits. In contrast, La Niña events result in a 3.2 %–9.9 % reduction in global fire emissions, with regional variability depending on the fire inventories used. In response, fire-induced PM<sub>2.5</sub> concentrations increase substantially during El Niño, rising by 27.5 %–71.0 % in Indonesia, 49.2 %–116.5 % in North America, and 17.5 %–42.6 % in Australia. Conversely, La Niña events lead to decreases of 26.6 %–52.5 %, 19.4 %–37.3 %, 14.5 %–24.4 % in these regions, respectively. These findings highlight the critical role of ENSO in shaping fire emissions and air pollution from regional to global scales, providing valuable insights for mitigating the impacts of climatic extremes on air quality.</div><div>摘要</div><div>厄尔尼诺-南方涛动 (ENSO) 是全球气候变化的主要驱动因素, 对区域火灾活动及其相关污染物排放有深远影响. 本研究分析了2000–2023年期间ENSO对全球火灾排放及火灾引起的PM<sub>2.5</sub>浓度的影响. 在厄尔尼诺事件期间, 由于异常增温和降水不足, 全球火灾排放增加5.9 %−20.0 %, 其中印度尼西亚, 北美和澳大利亚为火排放增幅最显著地区. 相比之下, 拉尼娜事件期间全球火灾排放减少3.2 %−9.9 %, 具体变化取决于所使用的火灾排放清单.在此背景下, 火灾引起的PM<sub>2.5</sub>浓度在厄尔尼诺事件期间显著增加, 印度尼西亚增加27.5 %−71.0 %, 北美增加49.2 %−116.5 %, 澳大利亚增加17.5 %−42.6 %; 而在拉尼娜事件期间, 这些地区的PM<sub>2.5</sub>浓度分别减少26.6 %−52.5 %, 19.4 %−37.3 %和14.5 %−24.4 %. 研究结果表明, ENSO从区域到全球尺度上深刻影响着火排放和空气污染物浓度, 相关结论为减缓极端气候事件对空气质量的影响提供了重要的科学依据.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 3","pages":"Article 100597"},"PeriodicalIF":2.3,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-01-28DOI: 10.1016/j.aosl.2025.100596
Caixia Liang , Jiacan Yuan
The likelihood of extreme heat occurrence is continuously increasing with global warming. Under high temperatures, humidity may exacerbate the heat impact on humanity. As atmospheric humidity depends on moisture availability and is constrained by air temperature, it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms. Here, a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point (a measure of humidity) on local temperature evolving with escalating global mean surface temperature. By applying these models to 297 weather stations in seven regions in China, the study analyzes historical trends of humid-heat and dry-hot days, and projects their changes under global warming of 2.0°C and 4.5°C. In response to global warming, rising trends of humid-heat extremes, while weakening trends of dry-hot extremes, are observed at most stations in Northeast China. Additionally, results indicate an increasing trend in dry-hot extremes at numerous stations across central China, but a rise in humid-heat extremes over Northwest China and coastal regions. These trends found in the current climate state are projected to intensify under 2.0°C and 4.5°C warming, possibly influenced by the heterogeneous variations in precipitation, soil moisture, and water vapor fluxes. Requiring much lower computational resources than coupled climate models, these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming, potentially informing the risk management of compound humid-heat extremes on a local scale.
{"title":"The evolving distribution of humidity conditional on temperature and implications for compound heat extremes across China in a warming world","authors":"Caixia Liang , Jiacan Yuan","doi":"10.1016/j.aosl.2025.100596","DOIUrl":"10.1016/j.aosl.2025.100596","url":null,"abstract":"<div><div>The likelihood of extreme heat occurrence is continuously increasing with global warming. Under high temperatures, humidity may exacerbate the heat impact on humanity. As atmospheric humidity depends on moisture availability and is constrained by air temperature, it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms. Here, a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point (a measure of humidity) on local temperature evolving with escalating global mean surface temperature. By applying these models to 297 weather stations in seven regions in China, the study analyzes historical trends of humid-heat and dry-hot days, and projects their changes under global warming of 2.0°C and 4.5°C. In response to global warming, rising trends of humid-heat extremes, while weakening trends of dry-hot extremes, are observed at most stations in Northeast China. Additionally, results indicate an increasing trend in dry-hot extremes at numerous stations across central China, but a rise in humid-heat extremes over Northwest China and coastal regions. These trends found in the current climate state are projected to intensify under 2.0°C and 4.5°C warming, possibly influenced by the heterogeneous variations in precipitation, soil moisture, and water vapor fluxes. Requiring much lower computational resources than coupled climate models, these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming, potentially informing the risk management of compound humid-heat extremes on a local scale.</div><div>摘要</div><div>本研究利用非交叉分位数平滑样条, 对中国七个气候分区的297个气象站分别建立了分位数回归模型, 模拟露点温度基于局地温度的条件概率密度分布对全球变暖的响应, 并预测了这些分布分别在2.0°C和4.5°C温升情景下的变化. 结果表明, (1) 这些分布对全球变暖的响应存在较大的区域异质性: 东北地区, 西北地区与沿海地区大多数站点呈现出极端湿热事件增加的趋势; 而中国中部地区的多个站点呈现出极端干热事件增加的趋势. (2) 这些趋势预计在2.0°C和4.5°C的温升情景下将进一步加剧.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100596"},"PeriodicalIF":3.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical simulation of the merging of a thunderstorm cluster from the mountain area near Beijing and a thunderstorm over the adjacent plains on 23 August 2021, along with a diagnosis and analysis of the cold pool and vertical motion, reveals the following: (1) The thunderstorm cluster in the mountain area moved slowly westward, weakening during its descent, whereas the thunderstorm cluster in the urban area moved rapidly eastward and intensified. Eventually, the two thunderstorm clusters encountered each other at the foot of the mountain and organized into a linear convective system. (2) Prior to merging, the thunderstorm cluster in the mountain area was blocked by warm advection to the east, causing the system to slow down, the cold pool to weaken, and the convergence and ascent associated with the cold pool outflow to diminish. In contrast, the thunderstorm cluster over the adjacent plains was driven by cold advection to the west, accelerating the system's movement, strengthening the cold pool, and enhancing the convergence and ascent driven by the cold pool outflow. After the thunderstorm clusters merged, the convergence of the northwesterly and southeasterly winds, as well as precipitation, led to the rapid accumulation of cold air, strengthening the cold pool and its upward development, which acted similarly to a terrain feature, further enhancing convergence and ascent. (3) The vertical motion reveals that before merging, the thunderstorm cluster in the mountain area was dominated by negative buoyancy at lower levels, which suppressed the development of ascent, whereas the thunderstorm cluster over the adjacent plains was driven by positive disturbances in the vertical pressure gradient force, which increased ascent. After the merging, the positive disturbances in the vertical pressure gradient force dominated below 2 km, and as the vertical motion increased, the positive buoyancy gradually became the dominant driver, further strengthening the ascent. The analysis suggests that the positive potential temperature disturbance and the southeasterly or southerly winds over the adjacent plains had opposing effects on the two approaching thunderstorm clusters, with the thunderstorm cluster over the adjacent plains taking the lead during the merging process.
{"title":"Mechanistic study of a downhill merging and enhancement of convection in Beijing","authors":"Xinyu Zhao , Lingkun Ran , Shunwu Zhou , Xinyong Shen , Mingxuan Chen , Yanli Chu","doi":"10.1016/j.aosl.2025.100595","DOIUrl":"10.1016/j.aosl.2025.100595","url":null,"abstract":"<div><div>Numerical simulation of the merging of a thunderstorm cluster from the mountain area near Beijing and a thunderstorm over the adjacent plains on 23 August 2021, along with a diagnosis and analysis of the cold pool and vertical motion, reveals the following: (1) The thunderstorm cluster in the mountain area moved slowly westward, weakening during its descent, whereas the thunderstorm cluster in the urban area moved rapidly eastward and intensified. Eventually, the two thunderstorm clusters encountered each other at the foot of the mountain and organized into a linear convective system. (2) Prior to merging, the thunderstorm cluster in the mountain area was blocked by warm advection to the east, causing the system to slow down, the cold pool to weaken, and the convergence and ascent associated with the cold pool outflow to diminish. In contrast, the thunderstorm cluster over the adjacent plains was driven by cold advection to the west, accelerating the system's movement, strengthening the cold pool, and enhancing the convergence and ascent driven by the cold pool outflow. After the thunderstorm clusters merged, the convergence of the northwesterly and southeasterly winds, as well as precipitation, led to the rapid accumulation of cold air, strengthening the cold pool and its upward development, which acted similarly to a terrain feature, further enhancing convergence and ascent. (3) The vertical motion reveals that before merging, the thunderstorm cluster in the mountain area was dominated by negative buoyancy at lower levels, which suppressed the development of ascent, whereas the thunderstorm cluster over the adjacent plains was driven by positive disturbances in the vertical pressure gradient force, which increased ascent. After the merging, the positive disturbances in the vertical pressure gradient force dominated below 2 km, and as the vertical motion increased, the positive buoyancy gradually became the dominant driver, further strengthening the ascent. The analysis suggests that the positive potential temperature disturbance and the southeasterly or southerly winds over the adjacent plains had opposing effects on the two approaching thunderstorm clusters, with the thunderstorm cluster over the adjacent plains taking the lead during the merging process.</div><div>摘要</div><div>以往针对北京平原雷暴群和下山雷暴群合并过程的研究相对较少, 利用WRF模拟数据对2021年8月23日一次此类对流活动过程分析发现： (1) 雷暴群前侧风场和热力条件的差异, 使得山区雷暴群移动和冷池发展受阻, 而平原雷暴群则相反, 最终在山脚处合并, 增强后的冷池起到类似地形作用, 增强辐合和上升运动； (2) 合并前, 山区雷暴群低层负热力浮力抑制上升运动发展, 平原雷暴群低层正扰动垂直气压梯度力加速上升运动, 合并后, 正扰动垂直气压梯度力 (2 km以下) 和正热力浮力 (2 km以上) 共同驱动上升运动发展. 本文主要对冷池和垂直运动分析, 以期为北京地区的临近预报提供一些有用的科学参考.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 6","pages":"Article 100595"},"PeriodicalIF":3.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The South China Sea winter monsoon (SCSWM), an integral component of the East Asian winter monsoon, connects extratropical and tropical regions. Utilizing ERA5 reanalysis and PAMIP simulations, the relationship between Arctic sea ice and the SCSWM is investigated. The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector, i.e., the Sea of Okhotsk and western Bering Sea. This link persists throughout the cold season, peaks when sea ice precedes the SCSWM by one month, and is independent of ENSO. North Pacific sea-ice loss weakens the meridional temperature gradient (MTG) and vertical wind shear in midlatitudes, reducing baroclinic eddy formation. Given the reduced zonal wind according to the thermal wind relation, the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation. This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N, which intensifies the divergent component of the SCSWM. The divergent northerly anomalies also lead to cold advection and subtropical cooling. The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward, creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM. These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM, holding substantial implications for the predictability of the SCSWM.
{"title":"A non-ENSO driver of the South China Sea winter monsoon: North Pacific sea ice","authors":"Chang Kong , Xiaodan Chen , Zhiping Wen , Yuanyuan Guo","doi":"10.1016/j.aosl.2025.100593","DOIUrl":"10.1016/j.aosl.2025.100593","url":null,"abstract":"<div><div>The South China Sea winter monsoon (SCSWM), an integral component of the East Asian winter monsoon, connects extratropical and tropical regions. Utilizing ERA5 reanalysis and PAMIP simulations, the relationship between Arctic sea ice and the SCSWM is investigated. The authors reveal that its strongest relationship with Arctic sea ice occurs in the North Pacific sector, i.e., the Sea of Okhotsk and western Bering Sea. This link persists throughout the cold season, peaks when sea ice precedes the SCSWM by one month, and is independent of ENSO. North Pacific sea-ice loss weakens the meridional temperature gradient (MTG) and vertical wind shear in midlatitudes, reducing baroclinic eddy formation. Given the reduced zonal wind according to the thermal wind relation, the reduced wave activity flux in the upper troposphere must be balanced by equatorward wind based on the quasi-geostrophic momentum equation. This generates an anomalous meridional overturning circulation with descent and low-level divergence around 30°N, which intensifies the divergent component of the SCSWM. The divergent northerly anomalies also lead to cold advection and subtropical cooling. The enhanced MTG due to the subtropical cooling and weakened MTG due to high-latitude warming closely tied to reduced North Pacific sea ice displace the westerly jet southward, creating cyclonic shears over the North Pacific and intensifying the rotational component of the SCSWM. These findings establish North Pacific sea ice as a non-ENSO driver of the SCSWM, holding substantial implications for the predictability of the SCSWM.</div><div>摘要</div><div>南海冬季风作为东亚冬季风系统的重要组成部分, 在热带与热带外地区的相互作用中发挥着重要作用. 使用大气再分析数据和环流模式试验, 本研究探讨了北极海冰与南海冬季风之间的关系. 研究表明, 影响南海冬季风的北极海冰关键区在鄂霍次克海. 以鄂霍次克海和西白令海为主的北太平洋海冰减少, 可通过调节垂直经向环流和副热带急流, 显著增强南海冬季风的辐散分量和旋转分量. 这一联系不受ENSO影响, 对南海冬季风的预测以及理解北极与热带之间的联系具有重要的科学意义.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 5","pages":"Article 100593"},"PeriodicalIF":2.3,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-01-15DOI: 10.1016/j.aosl.2025.100592
Xiaowei Tan , Zhiqiu Gao , Yubin Li
This study introduces a new ocean surface friction velocity scheme and a modified Thompson cloud microphysics parameterization scheme into the CMA-TYM model. The impact of these two parameterization schemes on the prediction of the movement track and intensity of Typhoon Kompasu in 2021 is examined. Additionally, the possible reasons for their effects on tropical cyclone (TC) intensity prediction are analyzed. Statistical results show that both parameterization schemes improve the predictions of Typhoon Kompasu's track and intensity. The influence on track prediction becomes evident after 60 h of model integration, while the significant positive impact on intensity prediction is observed after 66 h. Further analysis reveals that these two schemes affect the timing and magnitude of extreme TC intensity values by influencing the evolution of the TC's warm-core structure.
{"title":"Typhoon Kompasu (2118) simulation with planetary boundary layer and cloud physics parameterization improvements","authors":"Xiaowei Tan , Zhiqiu Gao , Yubin Li","doi":"10.1016/j.aosl.2025.100592","DOIUrl":"10.1016/j.aosl.2025.100592","url":null,"abstract":"<div><div>This study introduces a new ocean surface friction velocity scheme and a modified Thompson cloud microphysics parameterization scheme into the CMA-TYM model. The impact of these two parameterization schemes on the prediction of the movement track and intensity of Typhoon Kompasu in 2021 is examined. Additionally, the possible reasons for their effects on tropical cyclone (TC) intensity prediction are analyzed. Statistical results show that both parameterization schemes improve the predictions of Typhoon Kompasu's track and intensity. The influence on track prediction becomes evident after 60 h of model integration, while the significant positive impact on intensity prediction is observed after 66 h. Further analysis reveals that these two schemes affect the timing and magnitude of extreme TC intensity values by influencing the evolution of the TC's warm-core structure.</div><div>摘要</div><div>本研究将一种新的海洋表面摩擦速度方案和一种改进的Thompson云微物理参数化方案引入CMA-TYM台风模式. 研究了这两种参数化方案对2021年台风“圆规” (Kompasu) 移动路径和强度预报的影响. 此外, 还分析了它们对台风强度预报影响的可能原因. 统计结果表明, 这两种参数化方案都能提升对台风Kompasu路径和强度的预报能力. 在模式积分60小时后, 对路径预报的影响变得明显, 而在66小时后, 观察到对强度预报有显著的正影响. 进一步的分析表明, 这两种参数化方案能通过影响台风暖心结构的演变来影响台风强度极值出现的时间和幅度.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"19 1","pages":"Article 100592"},"PeriodicalIF":3.2,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145610570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2025-01-10DOI: 10.1016/j.aosl.2025.100591
Yuanyan Xu, Wenkai Li
Due to the high elevation and cold climate of the Tibetan Plateau, the western region retains extensive snow cover during the summer, which can exhibit rapid variability over the course of just a few days. This study utilizes numerical experiments to investigate the atmospheric response to extreme Tibetan Plateau snow cover (TPSC) events on a subseasonal timescale during summer. The results indicate that the subseasonal variations in TPSC exert limited impact on nonlocal atmospheric circulation and temperature during this period. Nevertheless, local surface energy and atmospheric temperature exhibit rapid cooling responses to increased snow cover. Specifically, an increase in snow cover over the western Tibetan Plateau leads to a sharp rise in surface albedo, resulting in a reduction in land surface energy and a negative response in the diabatic heating rate from the surface to 350 hPa locally. This negative diabatic heating response subsequently causes a decline in both surface and overlying atmospheric temperatures. The temperature response is confined to the western Tibetan Plateau and extends vertically from the surface to approximately 350 hPa. These extreme TPSC events and their associated atmospheric impacts occur within a two-week timescale.
{"title":"Subseasonal impact of extreme Tibetan Plateau snow cover on the local atmosphere in summer","authors":"Yuanyan Xu, Wenkai Li","doi":"10.1016/j.aosl.2025.100591","DOIUrl":"10.1016/j.aosl.2025.100591","url":null,"abstract":"<div><div>Due to the high elevation and cold climate of the Tibetan Plateau, the western region retains extensive snow cover during the summer, which can exhibit rapid variability over the course of just a few days. This study utilizes numerical experiments to investigate the atmospheric response to extreme Tibetan Plateau snow cover (TPSC) events on a subseasonal timescale during summer. The results indicate that the subseasonal variations in TPSC exert limited impact on nonlocal atmospheric circulation and temperature during this period. Nevertheless, local surface energy and atmospheric temperature exhibit rapid cooling responses to increased snow cover. Specifically, an increase in snow cover over the western Tibetan Plateau leads to a sharp rise in surface albedo, resulting in a reduction in land surface energy and a negative response in the diabatic heating rate from the surface to 350 hPa locally. This negative diabatic heating response subsequently causes a decline in both surface and overlying atmospheric temperatures. The temperature response is confined to the western Tibetan Plateau and extends vertically from the surface to approximately 350 hPa. These extreme TPSC events and their associated atmospheric impacts occur within a two-week timescale.</div><div>摘要</div><div>青藏高原海拔高, 气候寒冷, 其西部地区在夏季仍有积雪覆盖, 且积雪变化可能在数日内迅速发生. 本文通过数值试验研究了大气对夏季青藏高原极端积雪事件的次季节响应. 结果表明, 尽管极端积雪事件对非局地大气环流及温度的影响有限, 但局地地表能量收支和大气温度对积雪增加表现出快速的冷却响应. 具体而言, 青藏高原西部积雪增加会导致地表反照率迅速上升, 从而减少地表能量输入. 此变化引发了局地地表至350 hPa高度的非绝热加热率的负异常响应, 进而导致地表及上空大气温度下降. 气温响应主要局限于青藏高原西部, 并且从地表垂直延伸至约350 hPa高度. 上述夏季青藏高原极端积雪事件及其大气影响发生在两周时间内.</div></div>","PeriodicalId":47210,"journal":{"name":"Atmospheric and Oceanic Science Letters","volume":"18 5","pages":"Article 100591"},"PeriodicalIF":2.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144696477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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