利用高分辨率卫星的云顶黑体亮温(Black Body Temperature,TBB)资料,对2010~2022年暖季(5~9月)四川及其周边地区(25°N~35°N,96°E~110°E)中尺度对流系统(Mesoscale Convection Systems,MCSs)进行识别、追踪和分类。...利用高分辨率卫星的云顶黑体亮温(Black Body Temperature,TBB)资料,对2010~2022年暖季(5~9月)四川及其周边地区(25°N~35°N,96°E~110°E)中尺度对流系统(Mesoscale Convection Systems,MCSs)进行识别、追踪和分类。重点关注了4类MCS(即MCC、PECS、MβCCS和MβECS)的时空分布、活动特征及其对局部降水(夜间/白天)的贡献,并探讨了有利于MCS生成的大尺度环流条件。主要结论如下:β中尺度圆形的对流系统在该地区暖季最为常见。MCS分布较为分散,川西高原、四川盆地东部和南部是对流活动的活跃区,其中南部对流的夜发性显著。MCS的生成在7月最多,5月最少,而6月的对流发展最为旺盛。α中尺度圆形和β中尺度带状的MCS在成熟时具有更大的平均面积、更低的最低云顶温度和更长的生命史。4类MCS表现出发展慢、消亡快的特征,生成的峰值时段集中在午后17:00(北京时间,下同)至18:00。与MCS有关的降水占总降水量的25%以上,对夜间降水的贡献明显高于日间;对流层高空西风急流和反气旋性环流、对流层中低空浅槽、正相对涡度带和气旋性切变以及来自孟加拉湾的水汽为MCS的生成和维持提供了有利条件。展开更多
The chief objective of the article is to learn the spatial characteristics of stress distribution around a shallow buried cylinder Karst cave in limestone strata.Firstly,taking into account the geometry of limestone f...The chief objective of the article is to learn the spatial characteristics of stress distribution around a shallow buried cylinder Karst cave in limestone strata.Firstly,taking into account the geometry of limestone formations,and the characteristics of Karst geomorphology in China,a spatial axialsymmetrical hollow model was established.Concurrently,combining available work and the concept of elasticity,the boundary conditions are determined.Subsequently,Love displacement method was introduced,the expressions of stress components were gained.The diagram characteristics of each stress component are summarized,which are affected by various influencing factors.Finally,in order to prove the rationality of the general solution,numerical simulation was carried out on the basis of practical engineering,and the maximum error is less than 5%.Thus,the analytical solution could represent the spatial characteristics of stress distribution around a shallow buried cylinder Karst cave in limestone strata.展开更多
国家“十四五”规划和2035年远景目标提出,要基本消除重污染天气,持续改善京津冀及周边地区的环境质量。根据2021年京津冀及周边地区大气污染物浓度数据和GDAS(global data assimilation system)气象数据,探究区域重污染时空变化特征,...国家“十四五”规划和2035年远景目标提出,要基本消除重污染天气,持续改善京津冀及周边地区的环境质量。根据2021年京津冀及周边地区大气污染物浓度数据和GDAS(global data assimilation system)气象数据,探究区域重污染时空变化特征,分析典型过程中主要气流轨迹和污染物潜在来源分布。结果表明:时间分布上,1,3月重污染日数最多,8,9月无重污染日;重污染期间首要污染物以PM_(2.5)、PM_(10)和O_(3)为主。空间分布上,春、冬季在全域均发生重污染过程,夏、秋季仅局部发生;重度和严重污染天数呈空间显著聚集。典型重污染过程中,春季石家庄市PM_(10)以东部短距离输送和西北方向长距离输送为主,夏季太原市O_(3)以外来源排放和西北长距离输送为主,秋季鹤壁市PM_(2.5)以本地源排放和短距离输送为主,冬季开封市PM_(2.5)主要来自东部短距离输送。因此,应挖掘各重污染过程中首要污染物的分布特征和潜在源区,针对性制定联防联控措施,统筹协调重点区域内大气污染防治工作。展开更多
文摘利用高分辨率卫星的云顶黑体亮温(Black Body Temperature,TBB)资料,对2010~2022年暖季(5~9月)四川及其周边地区(25°N~35°N,96°E~110°E)中尺度对流系统(Mesoscale Convection Systems,MCSs)进行识别、追踪和分类。重点关注了4类MCS(即MCC、PECS、MβCCS和MβECS)的时空分布、活动特征及其对局部降水(夜间/白天)的贡献,并探讨了有利于MCS生成的大尺度环流条件。主要结论如下:β中尺度圆形的对流系统在该地区暖季最为常见。MCS分布较为分散,川西高原、四川盆地东部和南部是对流活动的活跃区,其中南部对流的夜发性显著。MCS的生成在7月最多,5月最少,而6月的对流发展最为旺盛。α中尺度圆形和β中尺度带状的MCS在成熟时具有更大的平均面积、更低的最低云顶温度和更长的生命史。4类MCS表现出发展慢、消亡快的特征,生成的峰值时段集中在午后17:00(北京时间,下同)至18:00。与MCS有关的降水占总降水量的25%以上,对夜间降水的贡献明显高于日间;对流层高空西风急流和反气旋性环流、对流层中低空浅槽、正相对涡度带和气旋性切变以及来自孟加拉湾的水汽为MCS的生成和维持提供了有利条件。
基金supported by National Natural Science Foundation of China(42002293,52068019)Hainan Provincial Natural Science Foundation of China(520QN229,422RC599)+2 种基金Independent Innovation Fund Project of Tianjin University and Hainan University(KF2022⁃03)Scientific Research Startup Foundation of Hainan university(KYQD(2R)1969)Systematic Project of Key Laboratory of Geological Hazards on Three Gorges Reservoir Area(Three Gorges University),Ministry of Education(2020KDZ04).
文摘The chief objective of the article is to learn the spatial characteristics of stress distribution around a shallow buried cylinder Karst cave in limestone strata.Firstly,taking into account the geometry of limestone formations,and the characteristics of Karst geomorphology in China,a spatial axialsymmetrical hollow model was established.Concurrently,combining available work and the concept of elasticity,the boundary conditions are determined.Subsequently,Love displacement method was introduced,the expressions of stress components were gained.The diagram characteristics of each stress component are summarized,which are affected by various influencing factors.Finally,in order to prove the rationality of the general solution,numerical simulation was carried out on the basis of practical engineering,and the maximum error is less than 5%.Thus,the analytical solution could represent the spatial characteristics of stress distribution around a shallow buried cylinder Karst cave in limestone strata.
文摘国家“十四五”规划和2035年远景目标提出,要基本消除重污染天气,持续改善京津冀及周边地区的环境质量。根据2021年京津冀及周边地区大气污染物浓度数据和GDAS(global data assimilation system)气象数据,探究区域重污染时空变化特征,分析典型过程中主要气流轨迹和污染物潜在来源分布。结果表明:时间分布上,1,3月重污染日数最多,8,9月无重污染日;重污染期间首要污染物以PM_(2.5)、PM_(10)和O_(3)为主。空间分布上,春、冬季在全域均发生重污染过程,夏、秋季仅局部发生;重度和严重污染天数呈空间显著聚集。典型重污染过程中,春季石家庄市PM_(10)以东部短距离输送和西北方向长距离输送为主,夏季太原市O_(3)以外来源排放和西北长距离输送为主,秋季鹤壁市PM_(2.5)以本地源排放和短距离输送为主,冬季开封市PM_(2.5)主要来自东部短距离输送。因此,应挖掘各重污染过程中首要污染物的分布特征和潜在源区,针对性制定联防联控措施,统筹协调重点区域内大气污染防治工作。
