亚洲季风降水的多模式模拟结果分析

利用参加政府间气候变化委员会(IPCC)第四次评估报告(AR4)的多个大气模式(包括中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室新发展的全球格点大气模式GAMIL)的AMIP-II(大气模式比较计划-II)积分的集合平均结果(MMEA),研究了当前大气模式对亚洲季风降水的平均模拟能力,同时也评估了GAMIL的模拟水平。对多年平均冬夏季降水的模拟研究发现:MMEA和GAMIL对冬季降水的模拟好于夏季。与以往的结果相比,MMEA对夏季印度洋和西太平洋地区降水的模拟改进不明显;部分模式能够模拟出夏季东亚副热带地区从中国东海到中太平洋的带状梅雨降水,但大部分模式的模拟强度还不够。可以看出GAMIL除了冬季印度洋和夏季菲律宾模拟的降水稍弱外,与MMEA的结果很接近。降水场的误差与环流场的误差对应。此外,作者还研究了降水的年际变化和季风爆发撤退过程的模拟能力。MMEA与观测在印度季风区降水的相关系数不如在东亚热带和东亚副热带季风区的好。各模式冬季的相关系数一般好于夏季,特别是东亚热带季风区冬季的相关系数普遍较高,而印度季风区夏季的相关系数普遍较低。MMEA对标准差的模拟并不总比单个模式的好。各个模式对东亚热带季风区冬季的降水距平同号率和降水距平百分率模拟得最好。季风爆发、撤退时降水推移的模拟也还有待于进一步提高。

Analysis of AGCMs in Asian Monsoon Precipitation Simulations

The performances of the AGCMs participating the Fourth Assessment Report of IPCC are analyzed in Asian monsoon precipitation simulations to assess the mean performance of contemporary AGCMs as well as that of GAMIL(the Grid-point Atmospheric Model of IAP LASG-GAMIL)relative to previous assessment.The MMEA is based on the equal-weighted average of each model.It indicates that the performance of climatological precipitation simulation in winter is better than that in summer.No obvious improvements are found in simulations of summer Indian Ocean and Western Pacific Ocean precipitation.Some of the AGCMs can simulate the Meiyu rain band from Eastern China Sea to mid Pacific of Eastern Asian Subtropical area well,but most can not.It is also shown that GAMIL has a similar performance with MMEA except a little weaker intensity simulation in winter Indian Ocean and summer Western Pacific Ocean.The error in precipitation simulation corresponds to that in circulation simulation.Moreover,the performances of precipitation simulation in interannual variability and during the period of the monsoon onset and retreat are evaluated.It is found that MMEA has better correlation coefficients with observation in Eastern Asian Tropical monsoon area and Eastern Asian Subtropical monsoon area than that in India monsoon area.Models generally have better correlation coefficients with observation in winter than that in summer,and the best in winter Eastern Asian Tropical monsoon area while the worst in summer Indian monsoon area.The standard deviation of MMEA is not always better than that of each single model.For each model,the area-averaged same sign ratio(with observation)and the percent of precipitation anomaly is the best in winter Eastern Asian Tropical monsoon area.The performances of monsoon precipitation during the period of monsoon onset and retreat need to be improved.