东亚地区500 hPa位势高度场NCEP/NCAR再分析资料与ERA-40资料的比较

运用统计分析方法对3份500 hPa位势高度场资料,即NCEP/NCAR全球大气再分析月平均资料和欧洲中心ERA-40资料,国家气候中心的NMC资料(该资料的基础是站点观测资料的实测数据,并结合中央气象台的日常累积资料整编而成)进行比较,以讨论NCEP/NCAR再分析资料与ERA-40资料以及NMC资料的相关性,尤其在东亚地区的可靠性.3份资料综合分析得到如下结论:在东亚地区,特别是贝加尔湖以南至中国西北和中西部的大部分区域内(30°-50°N,80°-115°E),NCEP/NCAR资料和ERA-40资料各季的平均场、相关场均存在大范围的显著性差异区,差异最大的季节在夏季,时段为1958-1970年,而在冬季相关较好.同时NCEP/NCAR资料在20世纪60年代初出现异常低值,在60年代中期有突然的增长,而欧洲中心的ERA-40资料和国家气候中心的NMC资料均无此现象.针对以上问题,对北半球500 hPa资料的使用提出如下建议:在东亚地区应用NCEP/NCAR资料时,如果范围涉及贝加尔湖以南至中国西北和中西部地区(30°-50°N,80°-115°E),尽量应用20世纪70年代以后的资料,尤其在春、夏两季;而该区域内的ERA-40资料和NMC资料在这一时段内是基本一致,具有可信性.

A comparison of 500 hPa field of East-Asia between the NCEP/NCAR reanalysis data and the ERA-40 of ECMWFdata

In this study, the 500 hPa geopotential height fields of the Northern Hemisphere based on the NCEP/NCAR reanalysis data, the ERA-40 of the ECMWF data and the China NMC data which are compiled according to the observations from the weather stations integrated with the routine data collecled by the Central Weather Service of China were be compared for the period 1957-2002.The differences of these data in the four seasons were depicted and discussed using statistical analysis methods. The main purpose of this study was to reveal the NCEP data adaprability and reliability in East-Asia. The reaults show that some obvious differences exist in either the mean fields or the correlation fields between the NCEP/NCAR reanalysis data and ERA-40 of the ECMWF data. The largest difference centers were located in the East-Asia, especially in the area from south of the Baikal Lake to northwest and middle of China (30°-50°N, 80°-115°E). The largest differences were in summer and the most interrelated season was winter for the period 1958-1970. In the meantime, the NCEP/NCAR reanalysis data shows an unusual low value compared with the ERA-40 of the ECMWF data during 1958-1962 with a obvious in crease from 1962 to 1969 followed. In contrary, both the ERA-40 of the ECMWF data and the China NMC data show no such anomolies. As a result, it is suggested that we should pay more attention to what range and season to be addressed when using the NCEP/NCAR 500 hPa reanalysis data on the East-Asia, especially on the area from south of the Baikal Lake to northwest and middle of China (30°-50°N, 80°-115°E) in Spring and Summer. As a matter of fact, the data since 1970s are the most desirable. On the other hand, the ERA-40 of the ECMWF data and the China NMC data are coincident with each other to a great extent on this area above during 1960s to 1970s, implying that both of them are more reliable.