The AsianAustralian Monsoon System Recent Evolution Current Status

The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 06 April 2009 For more information, visit: http: //www. cpc. ncep. noaa. gov/products/Global_Monsoons/Asian_Monsoons. shtml 1

Outline • Recent Evolution and Current Conditions • Monsoon Prediction • Summary • Climatology 2

Rainfall Patterns: Last 90 Days The CMAP dataset shows that, during the past 90 days, above-normal precipitation occurred over the tropical eastern Indian Ocean, southern South China Sea, the Philippine Sea, the Coral Sea, and much of the maritime continent. Precipitation was below normal over western Asia, eastern India, southern China, Korea, Madagascar, and central Indian Ocean. 3

Rainfall Patterns: Last 30 Days During the past 30 days, above-normal precipitation occurred over the tropical eastern Indian Ocean, the Philippine Sea, most of the maritime continent, and the tropical farwestern Pacific. Below-normal precipitation was observed over much of tropicalsubtropical Asia, subtropical northwestern Pacific, equatorial Indian Ocean, and most subtropical Southern Hemisphere including Australia. 4

Rainfall Patterns: Last 5 Days During the past week, rainfall was below normal over part of southern China, southern of Japan, Indonesia, northern Australia, and the central Indian Ocean. Above-normal rainfall was observed over the Persian Gulf and Iran, and southern Indian Ocean. 5

Rainfall Time Series over 5 x 5 lat-lon boxes *This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. • Associated with the La Nina condition, rainfall has been above normal over much of northern Australia and the maritime continent. However, the rainfall has decreased in the past week or so (middle and lower panels). • Dry condition continued over southern China after a rainy period (upper panel). 6

Atmospheric Circulation At the lower troposphere, anomalous anticyclonic patterns were observed over tropical central Southern Indian Ocean. The trade wind over tropical western Pacific has been enhancing from the previous week. 7

NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Week 1 & Week 2 Week-1 Week-2 8

Predictions of East Asia – NW Pacific Monsoon • Upper panel: East Asia – Western North Pacific (EAWNP) monsoon index (Wang et al. 2008) defined as U 850 (5 -15ºN, 40 -80ºE) – U 850 (2030ºN, 70 -90ºE). The NCEP Global Forecast System predicts that the EAWNP monsoon circulation will be near normal in the next two weeks. • Lower panel: Correlation between precipitation and the East Asia – Western North Pacific monsoon index (Wang et al. 2008; shading) and regression of 850 -mb winds on the monsoon index (vectors) for April. 9

Summary • During the past week, rainfall was below normal over part of southern China, southern of Japan, Indonesia, northern Australia, and the central Indian Ocean. Above-normal rainfall was observed over the Persian Gulf and Iran, and southern Indian Ocean. • The NCEP GFS predicts that the rainfall over Southern China will be below normal in the next week. 10

Onset of the Asian Monsoon 11

Climatology 12