Contribution of tropical cyclone rainfall at categories to total precipitation over the Western North Pacific from 1998 to 2007

Based on 10 years precipitation data from Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 and the best track data from China Meteorological Administration (CMA), the seasonal, monthly and annual contribution of tropical cyclone (TC) precipitation to the total rainfall are analyzed over the Western North Pacific (WNP) during 1998 to 2007 from May to December. The results show that: (1) TC seasonal rainfall contribution ranges from 4% in inland regions to above 40% in ocean-regions of 15A degrees N-25A degrees N. TCs at higher categories contribute much more to the total precipitation. (2) On monthly scale, TCs contribute 60% to the total rainfall regionally during whole TC season, which is the maximum contribution. The peak contribution of TC rainfall averaged in multi-months of the ten years occurs in August (28%) over the whole ocean impacted by TC and in December (23%) over the whole land impacted by TC, respectively. (3) On annual scale, the maximum contribution of TC precipitation to the total rainfall are in 2004 (similar to 30%) over ocean and in 1998 (similar to 20%) over land, respectively. (4) The contribution of TC precipitation to the total rainfall increases 6% (decreases 6%) in El Nio (La Nia) years compared with neutral years.