A Study of the Relationships between the East Asian Summer Monsoon and the Tropical Cyclone Frequency in the Northwestern Pacific
对东亚夏季风与西北太平洋热带气旋频数关系的初步分析

The relationships between the East Asian summer monsoon and the generating frequency of tropical cyclone in the northwestern Pacific (including the South China Sea) are investigated in the context of the index of land-sea thermal difference (I LSTD), 500 hPa height fields, OLR data, and NCEP/NCAR monthly mean reanalysis data. Results show that the change of intensity of the summer monsoon bears a close relation to the frequency of tropical cyclone in the northwestern Pacific. In strong summer monsoon years, the number of tropical cyclone in the northwestern Pacific is larger than normal while in weak years the contrary is the case in the synchronous season and the number of tropical cyclone is normal in the subsequent season. Furthermore, based on the large-scale conditions of tropical cyclone generating, its dynamic mechanism is discussed.