利用NCEP/NCAR再分析资料,通过合成分析、诊断分析等方法研究了淮河流域夏季降水异常年份的大尺度环流场,并且分析了造成这种环流背景的可能原因。结果表明:西风急流在多雨年和少雨年作为波导的作用没有变化,但多雨年西风急流的位置比...利用NCEP/NCAR再分析资料,通过合成分析、诊断分析等方法研究了淮河流域夏季降水异常年份的大尺度环流场,并且分析了造成这种环流背景的可能原因。结果表明:西风急流在多雨年和少雨年作为波导的作用没有变化,但多雨年西风急流的位置比少雨年偏东。在中高纬地区,多雨和少雨年200 h Pa沿西风急流的定常Rossby波列结构有明显的不同。在多雨年,有一条明显的沿西风急流传播的Rossby波列结构,波源位于西欧和中亚,波汇位于里海和我国淮河流域地区,日本以东的西北太平洋也是明显的波源区;在少雨年,西欧和中亚的波源地区的波活动明显减弱,原来位于淮河流域的波汇区南压到长江以南,西北太平洋上的波活动也明显减弱。这种波列结构的不同可能是造成淮河流域夏季降水异常的一个重要原因。展开更多
In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with th...In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.展开更多
文摘利用NCEP/NCAR再分析资料,通过合成分析、诊断分析等方法研究了淮河流域夏季降水异常年份的大尺度环流场,并且分析了造成这种环流背景的可能原因。结果表明:西风急流在多雨年和少雨年作为波导的作用没有变化,但多雨年西风急流的位置比少雨年偏东。在中高纬地区,多雨和少雨年200 h Pa沿西风急流的定常Rossby波列结构有明显的不同。在多雨年,有一条明显的沿西风急流传播的Rossby波列结构,波源位于西欧和中亚,波汇位于里海和我国淮河流域地区,日本以东的西北太平洋也是明显的波源区;在少雨年,西欧和中亚的波源地区的波活动明显减弱,原来位于淮河流域的波汇区南压到长江以南,西北太平洋上的波活动也明显减弱。这种波列结构的不同可能是造成淮河流域夏季降水异常的一个重要原因。
基金supported by the National Natural Science Foundation of China under Grant 41775073
文摘In late July and early August 2018,Northeast China suffered from extremely high temperatures,with the maxium temperature anomaly exceeding 6°C.In this study,the large-scale circulation features associated with this heat wave over Northeast China are analyzed using station temperature data and NCEP–NCAR reanalysis data.The results indicate that strong anomalous positive geopotential height centers existed from the lower to upper levels over Northeast China,and the related downward motions were directly responsible for the extreme high-temperature anomalies.The northwestward shift of the western Pacific subtropical high(WPSH)and the northeastward shift of the South Asian high concurrently reinforced the geopotential height anomalies and descending flow over Northeast China.In addition,an anomalous Pacific–Japan pattern in the lower troposphere led to the northwestward shift of the WPSH,jointly favoring the anomalous geopotential height over Northeast China.Two wave trains emanating from the Atlantic region propagated eastwards along high latitudes and midlatitudes,respectively,and converged over Northeast China,leading to the enhancement of the geopotential height anomalies.
