A Numerical Investigation of the Formation and Variation of Tropical Climate

热带气候形成与变化的数值研究

基本信息

批准号：
10640415
负责人：
XIE Shang-Ping
金额：
$ 1.73万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The northward departure of the Pacific intertropical convergencezone (ITCZ) is a long-standing mistery of tropical climate. We coupledan atmospheric general circulation model (CGM) with an ocean model of intermediate complexity to investigate the roles of continentalgeometry and ocean-atmosphere interaction in breaking the equatorial symmetry set by the annual-mean solar forcing. Basin-scale asymmetries in sea surface temperature and the ITCZ emege when an asymmetric feature is added to the continent on the eastern side of the ocean. By contrast, the coupled system remains symmetric when the same asymmetric continental feature is added onto the ocean western boundary. This result suggests that the American continents are more important in determining the asymmetric aspect of the Pacific climate than larger Eurasia.Despite sharing many common climatological feature, the Pacific and Atlantic display temporal variability of very different spatial patterns. The analysis of a simple coupled ocean-atmosphere model suggests that the Pacific, with a larger zonal dimension, will be dominated by the symmetric El Nino mode while the smaller Atlantic is likely to see both the symmetric and anti-symmetric modes of climate variability, a result consistent with observations.The Indian Ocean is unique among the tropical oceans, being dominated by strong seasonal monsoons. An atmospheric GCM is run under an idealized land-sea distribution, and its results reveal new aspects of summer monsoon dynamics that can explain its abrupt onset.

太平洋热带辐合带（ITCZ）的北移是热带气候的一个长期谜团。我们将大气环流模型（CGM）与中等复杂性的海洋模型结合起来，研究大陆几何和海洋-大气相互作用在打破年平均太阳强迫所设定的赤道对称性方面的作用。当向海洋东侧的大陆添加不对称特征时，海面温度和 ITCZ 浮现的盆地尺度不对称。相比之下，当相同的不对称大陆特征添加到海洋西边界时，耦合系统保持对称。这一结果表明，美洲大陆在决定太平洋气候的不对称方面比更大的欧亚大陆更为重要。尽管太平洋和大西洋具有许多共同的气候特征，但它们表现出非常不同的空间模式的时间变化。对简单的海洋-大气耦合模型的分析表明，纬向尺寸较大的太平洋将以对称厄尔尼诺模式为主，而较小的大西洋可能会同时出现对称和反对称的气候变率模式。结果与观测结果一致。印度洋在热带海洋中是独一无二的，以强烈的季节性季风为主。大气 GCM 在理想化的陆地-海洋分布下运行，其结果揭示了夏季季风动力学的新方面，可以解释其突然爆发。