On the Relation between Asian Summer Monsoon and Flood/Drought Events During July September in Fujian Province

Based on 1961-2003 NCEP/NCAR reanalysis treated with EOF, wavelet and cross wavelet techniques we investigate different space patterns of July-September precipitation over Fujian in relation to summer monsoon over the NW Pacific and Indian Ocean at a range of time scales. Results show that 1) the uniform rainfall all over the province and opposite distribution of precipitation in the SE to the NW part are the dominant modes, 2) the NW Pacific summer monsoon exerts steadier impacts on rainfall in the former case, manifested dominantly in the interannual variation especially after the mid 1980s, depending on the strong (weak) monsoon for excessive (insufficient) precipitation, with the response center in the eastern seaboard of the province whereas the Indian Ocean monsoon has rather stable influence on rainfall differing in amount between SE and NW Fujian, mainly in the interdecadal variation, and it also exerts remarkable effects on the interannual variation subsequent to the mid 1980s, relying on the intense (weak) monsoon for more (less) precipitation in the SE and less (more) in the NW part in this season. It follows that the NW Pacific (Indian) monsoon has its effect on the rainfall amount (space distribution) during July to September, and 3) with the strong monsoons over the two oceans the difference in rainfall between SE and NW Fujian is increased and in the opposite case precipitation is lower over much of the province, and when the monsoons are contrary in intensity the departure field shows a complicated pattern, manifesting pronounced locality.