大气再分析资料中潜在可预报性的特征及其差异

利用1957年9月—2002年8月ECMWF和NCEP/NCAR月平均再分析资料,分别讨论了冬季和夏季SLP(sea level pressure,海平面气压)、500hPa高度、200hPa纬向风和850hPa经向风年际变率的潜在可预报性特征。结果表明:热带地区的潜在可预报性较高,尤其是赤道中东太平洋地区,而中高纬地区的潜在可预报性则较低。比较两套资料潜在可预报性的异同后发现:南半球的差异均明显大于北半球,特别是南极地区;低层变量的差异均大于中高层变量;东亚大陆在冬、夏季均具有一定的潜在可预报性;冬季各变量均表现出东亚冬季风具有较高的年际变率潜在可预报性,且两套资料的差异较小;500hPa位势高度表现的东亚夏季风潜在可预报性在两套资料中较一致,而低层变量(SLP和850hPa经向风)表现的东亚夏季风年际变率潜在可预报性在两套资料中存在较大差异。

Characteristics of potential predictability in atmospheric reanalysis data and their differences

By using ECWMF and NCEP/NCAR monthly mean reanalysis data(from September 1957 to August 2002), characteristics of interannual potential predictability of SLP, 500 hPa geopotential height, 200 hPa zonal wind and 850 hPa meridional wind in winter and summer are analyzed respectively.The results show that the potential predictability is high in the tropics, especially the equatorial area and eastern Pacific.In contrast, the potential predictability is relatively low over the middle and high latitudinal areas.After comparing the differences between these two sets of reanalysis data, we find that the difference in the Southern Hemisphere is more obvious than that in the Northern Hemisphere, especially around the South Pole.The difference in low-level variables is larger than those in middle-and high-level variables.There exists some potential predictability in East Asian in both winter and summer.East Asian winter monsoon described by all the variables in both two sets of reanalysis data has high potential predictability with little difference.Only the East Asian summer monsoon described by 500 hPa geopotential height shows high potential predictability with little difference.There are obvious differences in East Asian summer monsoon''s potential predictability with low-level variables including SLP and 850 hPa meridional wind between the two sets of reanalysis data.