不同时间尺度上黄淮地区夏季降水异常成因及预测研究

利用1961—2006年中国降水资料、NCEP/NCAR再分析资料、NOAA海表温度资料,分析了黄淮地区夏季降水的年代际和年际变化特征,研究了不同时间尺度上降水异常成因。结果表明,年代际尺度上,当太平洋年代际振荡处在暖(冷)位相时,南方涛动偏弱(强),黄淮地区夏季降水偏多(少)。在年际及以下尺度上,当印度洋北部海温偏高、南部偏低时,500 hPa位势高度场上,中高纬乌拉尔山以东和鄂霍次克海附近出现明显的双阻塞高压,副热带高压偏强;200 hPa风场上,西风急流略偏南,黄淮流域上空西风偏强,为反气旋环流;850 hPa风场上,黄淮流域上空出现西南—东北风的切变,使得急流出口区右侧次级环流的异常上升支恰好位于黄淮流域上空,高低空环流的这种配置导致了黄淮流域上空降水偏多。进一步分析发现,利用印度洋海温作为预测因子,建立预测模型,对黄淮流域降水年际变率有较高的预测能力。

Study on the causes and prediction of summer precipitation in the Huanghuai area on different time scales

In this paper,using precipitation data for China,NCEP/NCAR reanalysis data and SST data provided from NOAA during the period of 1961-2006,the interdecadal and interanual characteristics and causes of precipitation in the Huanghuai area were studied.On the interdecadal scale,when the Pacific Decadal Oscillation(PDO) was in the warm phase,the Southern Oscillation was weaker and the precipitation in the Huanghuai area was heavier.However,when the PDO was in the cold phase,the Southern Oscillation was stronger and the precipitation in the Huanghuai area was lighter.On the interannual scale,when the SST was higher in the north and lower in the south of the India Ocean,the west pacific subtropical high was stronger and the double Blocking High appeared near the Ural mountains and Okhotsk at 500 hPa.The westerly jet was found to the south of the average position at 200 hPa.The anticyclone appeared in the Huanghuai area.The shear of northeast and southwest wind appeared in Huanghuai on an 850 hPa wind.The upward current was on the Huanghuai area.The circulation led to greater precipitation in the Huanghuai area.It was found that the prediction model built on the India Ocean SST had a more accurate prediction ability on the precipitation in the Huanghuai area.