南亚高压在NCEP-2和MERRA再分析资料中的对比分析

通过双线性插值、相关分析、Morlet小波分析等分析方法,围绕新高分辨率再分析资料MERRA的可用性,对比分析了NASA高分辨率再分析资料MERRA和NCEP-DOE（NCEP-2）再分析资料中100hPa南亚高压的活动特征.结果表明：100hPa上,NCEP-2和MERRA资料南亚高压的特征线数值不同,NCEP-2资料为1680dgpm,比MERRA资料大4dgpm,但MERRA资料南亚高压的范围明显大于NCEP-2资料.除东伸指数外,NCEP-2和MERRA资料反映的南亚高压同一特征指数年际变化趋势基本一致,特别是两种资料南亚高压脊线指数的年际变化曲线基本重合.以20世纪90年代初为界,之前,NCEP-2资料南亚高压东伸指数、面积指数和强度指数正异常,MERRA资料南亚高压东伸指数、面积指数和强度指数负异常,NCEP-2中的指数值大于MERRA中对应的指数值;之后,反之.NCEP-2和MERRA资料南亚高压面积指数、强度指数的气候均值间存在显著差异.NCEP-2和MERRA资料南亚高压强度指数的方差间存在显著差异.两种资料反映的夏季南亚高压同一特征指数的显著周期在1979～2009年有很好的一致性：都具有相同的显著周期,并且位相也基本吻合,但两种资料在反映南亚高压主周期特征上存在一定差异：南亚高压面积指数、强度指数在MERRA资料中以准4年周期为主,在NCEP-2资料中则同时表现为准4年和8～9年两个周期.

Comparision between NCEP and NASA Reanalysis Data in Activities of South Asia High

Through the bilinear interpolation, correlation analysis and Morlet wavelet analysis methods, surrounding on the usability of new high resolution seismic reanalysis data MERRA, we compare system characteristics （particularly in South Asia High） between MERRA and NCEP- 2 reanalysis data. The main results are as follows：At 100hPa, value of South Asia High （SAH） characteristic line in MERRA is smaller than value in NCEP -2 and its value is 1676dgpm, but the scope of SAH in MERRA data is significantly bigger than the scope in NCEP - 2 data. In addition to SAH eastward index, their interannual var- iability trends of the same SAH characteristic index are also similar, especially in two data, interannual variabilities of the SAH ridge line index curve coincide. Prior to the early 1990s, SAH eastward index, area index and intensity index in NCEP -2 data show positive anomalies ; the same indices in MERRA data show negative anomalies; corresponding to the indices in NCEP -2 data, the index value in MERRA data is smaller; after the early 1990s, and vice versa. There is no significant difference be- tween means of SAH eastward and ridge line index in two data. Only variances of SAH intensity index between NCEP -2 and MERRA data have significant differences, and NCEP - 2 greater than MERRA. The wavelet variance verification indicates that the same SAH characteristic index of NCEP -2 and MERRA data during 1979 and 2009 in summer are in good agreement： both have the same significant oscillation periods, and their phases are also consistent, but there are some differences between their predominant period： in MERRA data SAH area and intensity index performance quasi -4 years oscillation as the predomi- nant period; in NCEP- 2 data SAH area and intensity index performance quasi -4 years and 8 to 9 years oscillation at the same time.