Sea surface temperature anomaly(SSTA)is a major signal for prediction of summer precipitation in East Asia.The relationship between SSTA in the tropical oceans and summer precipitation in East Asia has been documented...Sea surface temperature anomaly(SSTA)is a major signal for prediction of summer precipitation in East Asia.The relationship between SSTA in the tropical oceans and summer precipitation in East Asia has been documented in many studies.However,the relationship between SSTA and late summer(July–August)precipitation(JAP)over Northeast China(NEC)on the interannual timescale has received little attention.In this study,we examine the relationship between Indian Ocean Basin warming(IOBW)anomalies in spring and the JAP in NEC since the early1960 s.A significant positive correlation is found between the spring IOBW index and JAP over NEC.The positive spring IOBW anomaly is followed by an anomalous anticyclone from Northwest Pacific to the Korean Peninsula.This anomalous anticyclone favors a significantly strong and northward western Pacific subtropical high(WPSH),which facilitates anomalous southerly winds over NEC and the transport of more water vapor into this region.Further analysis indicates that the spring IOBW anomalies have important impacts on the vertical air motion in the tropics and subtropics during the summer.Significant anomalous upward(downward)motion covering Indonesia(Northwest Pacific to the southern Korean Peninsula)occurs when the IOBW is in its positive phase,which favors the northward movement of the WPSH in late summer and more precipitation over NEC in July–August.Modulation of the atmospheric circulation by this mechanism further influences the JAP over NEC.展开更多
High temperature and high humidity pose notable threats to the health and survival of humans,and the impact of compound extreme events involving multiple meteorological elements is usually greater than the sum of the ...High temperature and high humidity pose notable threats to the health and survival of humans,and the impact of compound extreme events involving multiple meteorological elements is usually greater than the sum of the impacts of individual extreme events.However,there is limited research on the compound extreme meteorological events,defined based on the extreme of health risks rather than just the extreme of meteoro-logical elements,necessitating further investigation into their characteristics and underlying driving factors.Using daily records of emergency ambulance dispatches from selected Chinese cities,together with daily average temperature and relative humidity data,this study identified and quantified warm-wet compound extreme events with high health risks(HRWWs)that occurred in southern China during 1979-2022.Results revealed that HRWWs were most prevalent in the coastal region of southern China.The annual frequency of HRWWs across China underwent a marked shift in 2014,with the rapid increase in recent years primarily contributed by the increase in summer HRWWs and advance and extension of the period of occurrence of HRWWs in summer.Further analysis indicated that the changes in HRWWs in southern China during summer were primarily regulated by the EIl Nino-Southern Oscillation(ENSO)of the preceding winter and the springtime Indian Ocean basin-wide(IOBW)mode.El Nino and Indian Ocean warming force a reverse Walker circulation in the tropical Indian Ocean-western Pacific,strengthening the Philippine anticyclone(PAC)in summer.This weakens convection in the northwestern Pacific and enables the western Pacific subtropical high to extend westward over coastal areas of southern China.The resulting abnormal atmospheric circulation causes prevailing subsidence over southern China,which is unfavorable for precipitation but conducive to maintaining high surface temperatures.Despite reduced precipitation,water vapor flux is increased owing to strengthened southwesterlies associated with the PAC that enhance regional humidity.Consequently,as temperature and humidity levels rise,HRWWs occur more frequently in southern China,as evidenced since 2014.Further analysis suggested that the contribution of intensification of IOBW warming to the sudden increase in HRWW occurrence over the past decade has been greater than that of ENSO.展开更多
基金Supported by the National Key Research and Development Program of China(2018YFA0606301)National Natural Science Foundation of China(41875093,41705074,and 41530531).
文摘Sea surface temperature anomaly(SSTA)is a major signal for prediction of summer precipitation in East Asia.The relationship between SSTA in the tropical oceans and summer precipitation in East Asia has been documented in many studies.However,the relationship between SSTA and late summer(July–August)precipitation(JAP)over Northeast China(NEC)on the interannual timescale has received little attention.In this study,we examine the relationship between Indian Ocean Basin warming(IOBW)anomalies in spring and the JAP in NEC since the early1960 s.A significant positive correlation is found between the spring IOBW index and JAP over NEC.The positive spring IOBW anomaly is followed by an anomalous anticyclone from Northwest Pacific to the Korean Peninsula.This anomalous anticyclone favors a significantly strong and northward western Pacific subtropical high(WPSH),which facilitates anomalous southerly winds over NEC and the transport of more water vapor into this region.Further analysis indicates that the spring IOBW anomalies have important impacts on the vertical air motion in the tropics and subtropics during the summer.Significant anomalous upward(downward)motion covering Indonesia(Northwest Pacific to the southern Korean Peninsula)occurs when the IOBW is in its positive phase,which favors the northward movement of the WPSH in late summer and more precipitation over NEC in July–August.Modulation of the atmospheric circulation by this mechanism further influences the JAP over NEC.
基金supported by Guangdong Major Project of Basic and Applied Basic Research (2020B0301030004)the National Natural Science Foundation of China (42075040)+2 种基金Key Innovation Team of China Meteorological Administration (CMA2022ZD03)the National Natural Science Foundation of China under (41930967)the National Key Research and Development Program of China (2018YFA0606203).
文摘High temperature and high humidity pose notable threats to the health and survival of humans,and the impact of compound extreme events involving multiple meteorological elements is usually greater than the sum of the impacts of individual extreme events.However,there is limited research on the compound extreme meteorological events,defined based on the extreme of health risks rather than just the extreme of meteoro-logical elements,necessitating further investigation into their characteristics and underlying driving factors.Using daily records of emergency ambulance dispatches from selected Chinese cities,together with daily average temperature and relative humidity data,this study identified and quantified warm-wet compound extreme events with high health risks(HRWWs)that occurred in southern China during 1979-2022.Results revealed that HRWWs were most prevalent in the coastal region of southern China.The annual frequency of HRWWs across China underwent a marked shift in 2014,with the rapid increase in recent years primarily contributed by the increase in summer HRWWs and advance and extension of the period of occurrence of HRWWs in summer.Further analysis indicated that the changes in HRWWs in southern China during summer were primarily regulated by the EIl Nino-Southern Oscillation(ENSO)of the preceding winter and the springtime Indian Ocean basin-wide(IOBW)mode.El Nino and Indian Ocean warming force a reverse Walker circulation in the tropical Indian Ocean-western Pacific,strengthening the Philippine anticyclone(PAC)in summer.This weakens convection in the northwestern Pacific and enables the western Pacific subtropical high to extend westward over coastal areas of southern China.The resulting abnormal atmospheric circulation causes prevailing subsidence over southern China,which is unfavorable for precipitation but conducive to maintaining high surface temperatures.Despite reduced precipitation,water vapor flux is increased owing to strengthened southwesterlies associated with the PAC that enhance regional humidity.Consequently,as temperature and humidity levels rise,HRWWs occur more frequently in southern China,as evidenced since 2014.Further analysis suggested that the contribution of intensification of IOBW warming to the sudden increase in HRWW occurrence over the past decade has been greater than that of ENSO.
