中国区域位势高度场探空与再分析资料的对比分析

Comparison of geopotential height between reanalysis and radiosonde data over China

利用中国高空探空资料和NCEP/NCAR、ERA以及JRA 3种再分析资料,采用偏差、线性趋势、EOF等统计方法,分析、讨论了再分析资料位势高度场在中国区域的适用性问题。结果表明:在年平均场上,探空资料在中国北方地区对流层中存在上升趋势,在平流层低层存在下降趋势;并且有整层变化相同的年际变化特征和对流层南北方反位相变化的年代际变化特征。再分析资料位势高度场数值上普遍小于探空资料;NCEP/NCAR资料与探空资料较为接近。在季节平均场上,探空资料在冬季对流层中存在一致的上升趋势,在春、夏和秋季的长期变化趋势与年平均场类似;探空资料与再分析资料在冬季的偏差最小。不同资料的EOF第一模态分布,在不同季节中差别较大,NCEP/NCAR资料在春季、夏季和冬季适用性较高,ERA资料在秋季适用性较高。

Based on the radiosonde and reanalysis data from NCEP/NCAR, ERA and JRA, by using deviation, linear trend, EOF statistics methods, the applicability evaluation of the atmospheric geo- potential heights in China is conducted in this paper. Results indicate that the annual mean geopotential heights are going up in the troposphere while a drop exists in the tropopause and lower stratosphere over the northern China. An in-phase variation in geopotential heights over the whole troposphere on interannu- al time scale and an anti-phase one over the north and south China on deeadal time-scale are obvious. Generally, the geopotential height values of the three reanalysis datasets are lower than that of observa- tion, among them, the NCEP geopotential height is the closest to the observation. In terms of seasonal mean field, geopotential heights show an upward trend in the troposphere in winter, while in other sea- sons, the trend is consistent with that of annual mean field. In addition, the smallest deviation between radiosonde and reanalysis datasets appears in winter. Overall, NCEP geopotential heights agree well with the observed ones in spring, summer and winter, while ERA performs much better in autumn.