摘要
Using 132-member experiments based on a linear baroclinic atmospheric model(LBM), this study investigates the optimal heat source forcing the interannual variability of the western North Pacific summer monsoon(WNPSM). The 132 members are forced by localized atmospheric heat sources distributed homogeneously over regions from 55°S to 55°N, each 10° latitude × 30° longitude in size. The atmospheric responses to all the heating constitute an ensemble to examine the relative contribution of each local heat source to the strength of the WNPSM. The result indicates that the combination of an atmospheric heating(cooling) source over the subtropical Northwest Pacific and a cooling(heating) source over the tropical Indian Ocean and the midlatitudes from China to the southern part of Japan is the pattern most effective at enhancing(weakening) the WNPSM.Besides, the optimal heat source pattern identified by the LBM simulations is similar to the observed atmospheric heating anomalies associated with WNPSM interannual variability. The results suggest that any external forcing that leads to a similar heating structure as the optimal thermal forcing pattern could lead to an anomalous WNPSM.
西北太平洋夏季风是热带影响东亚气候的桥梁,具有很强的年际变率。西北太平洋夏季风异常能造成东亚夏季旱涝和高低温灾害,因此研究它的年际变率驱动因子具有重要意义。本文利用一个格林函数方法定量的评估了热带各个格点热源对西北太平洋夏季风的贡献。具体为将南北55纬度之间的区域划分成132个小格子,在每个格子加上一个椭圆形理想热源;接着利用一个线性理论大气环流模式计算每个热源对西北太平洋夏季风的贡献。研究表明导致西北太平洋夏季风增强的最理想加热场结构是位于热带印度洋和中纬度东亚地区上空的冷源和位于副热带西北太平洋地区的热源。
基金
The study was jointly supported by the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA20060502]
the National Natural Science Foundation of China[grant numbers 41425086,41661144016,and 41706026]
the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences[project number LTO1704].
