Persistent heavy rainfall events(PHREs)over the Yangtze–Huaihe River Valley(YHRV)during 1981–2020 are classified into three types(type-A,type-B and type-C)according to pattern correlation.The characteristics of the ...Persistent heavy rainfall events(PHREs)over the Yangtze–Huaihe River Valley(YHRV)during 1981–2020 are classified into three types(type-A,type-B and type-C)according to pattern correlation.The characteristics of the synoptic systems for the PHREs and their possible development mechanisms are investigated.The anomalous cyclonic disturbance over the southern part of the YHRV during type-A events is primarily maintained and intensified by the propagation of Rossby wave energy originating from the northeast Atlantic in the mid–upper troposphere and the northward propagation of Rossby wave packets from the western Pacific in the mid–lower troposphere.The zonal propagation of Rossby wave packets and the northward propagation of Rossby wave packets during type-B events are more coherent than those for type-A events,which induces eastward propagation of stronger anomaly centers of geopotential height from the northeast Atlantic Ocean to the YHRV and a meridional anomaly in geopotential height over the Asian continent.Type-C events have“two ridges and one trough”in the high latitudes of the Eurasian continent,but the anomalous intensity of the western Pacific subtropical high(WPSH)and the trough of the YHRV region are weaker than those for type-A and type-B events.The composite synoptic circulation of four PHREs in 2020 is basically consistent with that of the corresponding PHRE type.The location of the South Asian high(SAH)in three of the PHREs in 2020 moves eastward as in the composite of the three types,but the position of the WPSH of the four PHREs is clearly westward and northward.Two water vapor conveyor belts and two cold air conveyor belts are tracked during the four PHREs in 2020,but the water vapor path from the western Pacific is not seen,which may be caused by the westward extension of the WPSH.展开更多
采用国家气候中心的全国160个和东北88个测站1960~2010年的逐月观测资料、美国NCEP/NCAR的再分析资料,对东北区夏季低温事件概率的空间分布与冷空气活动路径及其环流特征进行了分析,结果表明:东北区测站严重冷夏A事件≥20%概率区主要分...采用国家气候中心的全国160个和东北88个测站1960~2010年的逐月观测资料、美国NCEP/NCAR的再分析资料,对东北区夏季低温事件概率的空间分布与冷空气活动路径及其环流特征进行了分析,结果表明:东北区测站严重冷夏A事件≥20%概率区主要分布在黑龙江省的大部和吉林省的中东部,概率大值轴呈东北-西南向分布;东北区测站冷夏B事件≥20%概率区主要分布在东北区的中西部和长白山东部区,概率大值轴呈西北-东南向分布;5个A事件典型年的500 h Pa亚洲地区呈现乌拉尔山与鄂霍次克海阻高,与东北区均为负距平区构成双阻塞偶极子流型,偏东和偏北区域为温度场负距平极值中心;5个B事件典型年则巴尔喀什湖和贝加尔湖为正异常区,东北亚至北太平洋阿留申群岛附近上空为负距平区,构成亚洲地区东西向偶极子阻塞流型,温度场负距平分布为偏西北-东南走向;选择850 h Pa的假相当位温θse的316 K候平均等值线的变化,反映来源于极地或超极地的冷空气活动路径的时空范围,其A和B事件典型年冷空气活动路径均分别与与东北区A、B事件大概率区的主要轴向分布是吻合的。展开更多
基金This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA23090101)National Natural Science Foundation of China(Grant No.41975056).
文摘Persistent heavy rainfall events(PHREs)over the Yangtze–Huaihe River Valley(YHRV)during 1981–2020 are classified into three types(type-A,type-B and type-C)according to pattern correlation.The characteristics of the synoptic systems for the PHREs and their possible development mechanisms are investigated.The anomalous cyclonic disturbance over the southern part of the YHRV during type-A events is primarily maintained and intensified by the propagation of Rossby wave energy originating from the northeast Atlantic in the mid–upper troposphere and the northward propagation of Rossby wave packets from the western Pacific in the mid–lower troposphere.The zonal propagation of Rossby wave packets and the northward propagation of Rossby wave packets during type-B events are more coherent than those for type-A events,which induces eastward propagation of stronger anomaly centers of geopotential height from the northeast Atlantic Ocean to the YHRV and a meridional anomaly in geopotential height over the Asian continent.Type-C events have“two ridges and one trough”in the high latitudes of the Eurasian continent,but the anomalous intensity of the western Pacific subtropical high(WPSH)and the trough of the YHRV region are weaker than those for type-A and type-B events.The composite synoptic circulation of four PHREs in 2020 is basically consistent with that of the corresponding PHRE type.The location of the South Asian high(SAH)in three of the PHREs in 2020 moves eastward as in the composite of the three types,but the position of the WPSH of the four PHREs is clearly westward and northward.Two water vapor conveyor belts and two cold air conveyor belts are tracked during the four PHREs in 2020,but the water vapor path from the western Pacific is not seen,which may be caused by the westward extension of the WPSH.
文摘采用国家气候中心的全国160个和东北88个测站1960~2010年的逐月观测资料、美国NCEP/NCAR的再分析资料,对东北区夏季低温事件概率的空间分布与冷空气活动路径及其环流特征进行了分析,结果表明:东北区测站严重冷夏A事件≥20%概率区主要分布在黑龙江省的大部和吉林省的中东部,概率大值轴呈东北-西南向分布;东北区测站冷夏B事件≥20%概率区主要分布在东北区的中西部和长白山东部区,概率大值轴呈西北-东南向分布;5个A事件典型年的500 h Pa亚洲地区呈现乌拉尔山与鄂霍次克海阻高,与东北区均为负距平区构成双阻塞偶极子流型,偏东和偏北区域为温度场负距平极值中心;5个B事件典型年则巴尔喀什湖和贝加尔湖为正异常区,东北亚至北太平洋阿留申群岛附近上空为负距平区,构成亚洲地区东西向偶极子阻塞流型,温度场负距平分布为偏西北-东南走向;选择850 h Pa的假相当位温θse的316 K候平均等值线的变化,反映来源于极地或超极地的冷空气活动路径的时空范围,其A和B事件典型年冷空气活动路径均分别与与东北区A、B事件大概率区的主要轴向分布是吻合的。
