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Roles of airsea and land-air interactions on East Asian monsoon variability during transition seasons

海陆空相互作用对东亚季风过渡季节变化的作用

基本信息

批准号：
15540416
负责人：
TANIMOTO Youichi
金额：
$ 1.86万
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：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

We examined thermal and dynamical structures of the lower atmosphere over the extratropical temperature front near Kuroshio extension and Oyashio where the deformation scale is less than a few of 100km. In addition, we also see the relation of sea surface temperature (SST) and surface air temperature to the surface wind velocity not only in the extratropics, but also tropics for the comparison. Over the warm flank of the thermal front near Kuroshio extension, the planetary boundary layer develops to 1000-1500m height because the static stability near the surface is very unstable. This unstable condition enhances the vertical mixing of the momentum, heat and moisture. As a result, a mixed momentum induces the acceleration of the surface wind over the warm water. This notion is not agreement with the conventional view of the extratropical air-sea interaction : the strong surface wind induces the cool ocean. These results indicate that that the ocean does in fact make feed back to the atmosphere. This does not mean that the traditional relationship is wrong, but rather that in these mid-latitude regions, a two-way relationship between the atmosphere and ocean exists. In addition, our analysis shows that the atmospheric response to this oceanic forcing appears to include the anomalous storm track activity. The observed atmospheric anomalies, which may be, in part, forced by the preexisting SST anomalies in those regions.

本文研究了黑潮延伸区和俄亥俄附近的对流层外温度锋面低层大气的热力和动力结构，这里的形变尺度小于几百公里。此外，我们也看到海表温度（SST）和地面气温与地面风速的关系，不仅在热带外，而且在热带的比较。在黑潮延伸区附近的热锋暖侧翼，由于近地面的静力稳定度很不稳定，行星边界层发展到1000- 1500米高度。这种不稳定的条件增强了动量、热量和水分的垂直混合。结果，混合动量导致暖水表面风的加速。这一观点与对流层外海气相互作用的传统观点不一致：强的地面风导致冷的海洋。这些结果表明，海洋实际上确实向大气反馈。这并不意味着传统的关系是错误的，而是在这些中纬度地区，大气和海洋之间存在着双向关系。此外，我们的分析表明，这种海洋强迫的大气响应似乎包括异常风暴轴活动。观测到的大气异常，可能部分是由这些区域先前存在的SST异常造成的。