太平洋副热带高压及南亚高压在NCEP／NCAR和ECMWF再分析资料中的对比研究

ECMWF REANALYSIS DATASETS COMPARISONS OF THE WEST PACIFIC SUBTROPICAL HIGH AND OF THE SOUTH ASIA HIGH BETWEEN NCEP/NCAR AND

利用NCEP/NCAR和ECMWF 1961～2000年北半球逐月平均的500 hPa和100 hPa高度场再分析资料对影响我国天气、气候的重要系统——北半球西太平洋副热带高压以及南亚高压做了对比研究,发现两者在不同的再分析资料中虽然具有一定的相似性,但也存在着明显的区别。在1980年以前两者存在较大差异。NCEP/NCAR再分析资料分析出的副高明显偏弱,而其所反映的副高的变化在幅度和强度上均大于ECMWF再分析资料的结果。进一步分析发现,NCEP/NCAR再分析资料所得出的副高的年代际变化可能是不真实的。在1969年、1979～1991年间,NCEP/NCAR再分析资料中的南亚高压中心强度明显比ECMWF的强,特别是1992～1995年间,NCEP/NCAR再分析资料中的南亚高压中心强度更强且中心范围更大。此外,NCEP/NCAR再分析资料所反映的南亚高压的变化在幅度和强度上也都大于ECMWF再分析资料的结果。

Comparisons of the west Pacific subtropical high and of the south Asia high are made in terms of NCEP/NCAR and ECMWF 500 hPa and 100 hPa monthly geopotential height fields of Northern Hemisphere during the period 1961～2000. Discrepancies are found especially around the year 1980. The west Pacific subtropical high in NCEP/NCAR data is less intensive than that in ECMWF data before 1980. The range and strength of the west Pacific subtropical high variation described by NCEP/NCAR data is above those depicted in ECMWF data. The same situation appears in the 100hPa geopotential field. These discoveries imply that the interdecadal variation of the two systems may not be true. Besides, the South Asia high center in NCEP/NCAR data is obviously stronger than that in ECMWF data during the period 1969, 1979～1991 and 1992～1995. Furthermore, the range is larger from 1992 to 1995.