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
温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化...温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化意义重大。前期研究大都从年或季节尺度探究气候变化对草地生产力的影响特征,缺乏更精细时间尺度的关联分析。本研究基于1997—2020年青藏高原高寒草原长期植被观测数据及相应气候资料,应用简单线性回归及偏最小二乘回归法(Partial Least Squares regression,PLS)探究了研究区草地地上净初级生产力对日尺度温度和降水变化响应特征。结果表明:(1)近24 a来研究区年平均气温和降水量分别以0.03℃/a和4.36 mm/a的速率显著升高;(2)近24 a来研究区草地生产力显著升高(增幅为5.24 g m^(-2)a^(-1)),且与年平均温度和降水量呈显著正相关关系;(3)日尺度分析表明,不同阶段温度和降水变化对草地生产力的影响不同,其中5—8月和9—10月的温度及5—7月和9—11月的降水是影响研究区草地生产力的气候因子关键作用期,尤以生长季温度(5—8月)和降水(5—7月)变化影响更高,这表明生长季气候变化是该高寒草地生产力变化的主要驱动因素。总之,本研究指出近24 a生长季温度和降水量显著增加对高寒草原生产力具有重要促进作用,这意味着青藏高原暖湿化对高寒草原生态系统功能(草地生产力)影响不仅依赖于温度和降水变化的幅度,同时亦与温度和降水变化的方向和是否同步密切相关。展开更多
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.
文摘温度和降水变化显著影响高寒生态系统植被生长和系统功能。草地生产力作为草地系统功能强弱的重要体现,对气候变化,特别是温度和降水变化十分敏感。探究高寒草原生产力如何响应气候变化,对预测未来气候变化情景下高寒草地系统功能变化意义重大。前期研究大都从年或季节尺度探究气候变化对草地生产力的影响特征,缺乏更精细时间尺度的关联分析。本研究基于1997—2020年青藏高原高寒草原长期植被观测数据及相应气候资料,应用简单线性回归及偏最小二乘回归法(Partial Least Squares regression,PLS)探究了研究区草地地上净初级生产力对日尺度温度和降水变化响应特征。结果表明:(1)近24 a来研究区年平均气温和降水量分别以0.03℃/a和4.36 mm/a的速率显著升高;(2)近24 a来研究区草地生产力显著升高(增幅为5.24 g m^(-2)a^(-1)),且与年平均温度和降水量呈显著正相关关系;(3)日尺度分析表明,不同阶段温度和降水变化对草地生产力的影响不同,其中5—8月和9—10月的温度及5—7月和9—11月的降水是影响研究区草地生产力的气候因子关键作用期,尤以生长季温度(5—8月)和降水(5—7月)变化影响更高,这表明生长季气候变化是该高寒草地生产力变化的主要驱动因素。总之,本研究指出近24 a生长季温度和降水量显著增加对高寒草原生产力具有重要促进作用,这意味着青藏高原暖湿化对高寒草原生态系统功能(草地生产力)影响不仅依赖于温度和降水变化的幅度,同时亦与温度和降水变化的方向和是否同步密切相关。
