摘要
对IAP/LASG气候系统模式试验版(FGCM0)模拟对流层上层东亚副热带西风急流季节变化的能力进行评估,分析FGCM0模拟的东亚副热带西风急流季节变化与NCEP/NCAR再分析资料的差异及其与对流层大气南北温差的关系。结果表明,FGCM0模拟的冬季和夏季西风急流垂直结构、水平结构和季节变化与NCEP/NCAR再分析资料基本一致,但FGCM0模拟的东亚副热带西风急流在高原附近地区冬季和夏季都偏强,沿115°E中国大陆地区上空模拟的急流强度冬季偏弱,夏季明显偏强。夏季FGCM0模拟的急流中心位于高原东北部的40°N附近地区,强度偏强,位置偏东,而此时NCEP/NCAR再分析资料中的急流中心却位于高原北侧。此外,FGCM0模拟的急流在5月份的北移和8月份的最北位置上与NCEP/NCAR再分析资料差异较大。分析副热带西风急流与对流层南北温差的季节变化发现,急流出现的位置总是对应着对流层南北温度差较大区域,与再分析资料相比,FGCM0模拟的温度差在冬季基本一致,夏季差异较大。与降水的模拟相联系发现,FGCM0模拟得到的与实际不一致的偏西偏北的强降水中心与200 hPa上的东亚副热带急流位置和强度不合理具有密切关系。相关分析表明,冬季西风急流强度与日本南部海区的感热通量、夏季与青藏高原地区的地面感热通量有明显的正相关关系,而FGCM0能够较好地模拟冬季西风急流强度与地面感热通量之间的相关关系,但模拟夏季青藏高原地区感热通量和副热带西风急流之间相关关系的能力相对较差,夏季西风急流强度与OLR之间却有一定的关系。由于与强降水区相联系的OLR低值区对应着较大的对流凝结加热,再加上模式中位于青藏高原东南部较大的地面感热加热,增强了对流层的南北向温度差,进而影响东亚副热带急流强度和位置。因此,FGCM0模拟的夏季副热带急流位置和强度偏差与高原附近地区的地面感热加热、大气射出长波辐射等的模拟偏差具有密切的关系。
The performance of IAP/LASG climate system model （FGCM0） for simulating the seasonal variation of East Asian subtropical westerly jet （EAWJ） in the upper troposphere is evaluated by analyzing the differences between the coupled model results and the NCEP/NCAR reanalysis, and the relationship between the EAWJ seasonal variation and the atmospheric temperature difference in the upper troposphere from north to south is also been analyzed. The results show that the simulated vertical and horizontal structures and the seasonal variation of EAWJ in FGCM0 are consistent with the NCEP/NCAR reanalysis in winter and summer, but considerable biases in EAWJ strength and location exist in FGCM0. The EAWJ strength is too strong around the Tibetan Plateau in winter and summer, but too weak over eastern China along 115°E in winter and too strong in summer. The EAWJ center is located at 40°N of the northeastern Tibetan Plateau in summer,whereas the EAWJ center in NCEP/NCAR reanalysis is situated on the northern side of the Tibetan Plateau. In addition, there exist obvious biases in simulating EAWJ northward migration in May and the location in August. Analysis of the EAWJ seasonal variation and the atmospheric temperature difference from north to south in the troposphere indicates that the EAWJ center always corresponds to the largest atmospheric temperature difference from south to north in the troposphere. Compared with the NCEP/NCAR reanalysis, the simulated temperature differences in FGCM0 are reasonable in winter, and apparent discrepancies occur in summer. Comparison of the simulated and observed precipitation indicates that unrealistic heavy precipitation center is related to the location and intensity biases in the subtropical westerly jet. The correlation analysis shows that there exist significant positive correlations between the winter EAWJ strength and the surface sensible heat flux in the ocean area of southern Japan, and between summer EAWJ strength and the surface sensible heat flux in the Tibetan Plateau. FGCM0 can simulate the positive correlation in winter reasonably, but cannot simulate the positive correlation around the Tibetan Plateau in summer. The outgoing longwave radiation （OLR） also affects the simulated subtropical westerly jet.
出处
《大气科学》
CSCD
北大核心
2006年第6期1177-1188,共12页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40333026
中国科学院知识创新工程重要方向项目ZKCX2-SW-210
关键词
东亚
副热带西风急流
季节变化
海气耦合模式
East Asian subtropical westerly jet, seasonal variation, coupled climate model
