东亚夏季风年代际变化的若干重要特征及两份大气再分析资料的异同

本文利用ERA和NCEP/NCAR再分析资料，以及部分观测资料，研究了东亚夏季风年代际变化的若干重要特征. 结果表明，东亚夏季风在20世纪70年代末减弱这一现象是普遍存在的，主要表现为江淮地区表面温度降低，海平面气压升高，出现偏北风异常. 研究发现，这次年代际变化还体现在与东亚季风环流密切相关的重要环流因子，如西太平洋副热带高压、欧亚西风、澳大利亚高压、南极涛动等，它们在20世纪70年代末以后都进入高指数时期. 此外，文章还揭示：ERA和NCEP/NCAR再分析资料在东亚夏季风年代际变化上基本吻合，但也有很多差别.

Features of interdecadal changes of the East Asian summer monsoon and similarity and discrepancy in ERA-40 and NCEP/NCAR Reanalysis

This study investigates features of interdecadal changes of the East Asian summer monsoon (EASM) by using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Aanalysis (ERA-40), the National Centers for Environmental Prediction-National Center for Atmospherics Research (NCEP/NCAR) Reanalysis and observations for the period 1958～1998.Weakening of EASM after the late 1970s is presented as decreasing surface air temperature, rising sea level pressure and northern wind anomaly over JiangHuai valley. Besides the local elements, the interdecadal changes appear in those systems related, such as western Pacific subtropical high, westerlies over Eurasian continent, Australian high and Antarctic Oscillation, which become stronger after 1970s than before. Both Reanalysis data sets showing similar features of the interdecadal changes still have many differences.