Analysis and Numerical Simulations of the Teleconnection Between Indian Summer Monsoon and Precipitation in North China

In the early 1980s, Chinese meteorologists discovered the positive correlation in summer rainfall be-tween India and North China and the correlation was later con rmed by some researches in and outside China. Based on a variety of meteorological data from 1951 to 2005 and numerical simulations, the present study investigates such a correlation between Indian summer monsoon (ISM) and precipitation in North China. Furthermore, we discuss the intrinsic relations of the positive (Northwest India)-negative (the Tibetan Plateau)-positive (North China) precipitation anomaly teleconnection pattern from two aspects of thermal and dynamical factors, which not only con rms the precipitation teleconnection previously discovered again, but also reveals the influence mechanism of the ISM on the rainfall in North China. The results show that: (1) When the ISM is strong (weak), the precipitation in North China tends to be more (less) than normal; however, when the rainfall in North China is more (less) than normal, the probability of the strengthening (weakening) of the ISM is relatively lower. This implies that the ISM anomaly has more impact on the rainfall in North China. (2) The Indian low usually dominantly impacts the intensity of the ISM. When the Indian low deepens, the low troughs in mid-high latitudes are frequently strengthened, and the ridge of the western Pacific subtropical high (WPSH) extends westward. The southwesterly water vapor transport originated from low-latitudes and the southeasterly water vapor transport along the southwestern flank of the WPSH converge in North China, which is favorable for more rainfall there than normal, and vice versa. (3) The simulations from the regional climate model developed by National Climate Center (ReGCM??NCC) capture the salient feature of the precipitation teleconnection between India and North China. The simulated anomalous atmospheric circulations are close to observations, which con rms the existence of such a teleconnection from another angle.