Download
1 / 12
120 likes | 121 Vues
This report provides an update on the recent evolution and current conditions of the Asian-Australian monsoon system, along with predictions for the future. It includes information on rainfall patterns, atmospheric circulation, and forecast models.
E N D
The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 9 March 2009 For more information, visit:http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml
Outline • Recent Evolution and Current Conditions • Monsoon Prediction • Summary • Climatology
Rainfall Patterns: Last 90 Days The CMAP dataset shows that, during the past 90 days, above-normal precipitation occurred over the Australian monsoon region, the tropical eastern Indian Ocean, southern South China Sea, the Philippine Sea, and the waters east-southeast of Japan. Precipitation was below normal over western Asia, India, southern China, Korea, Madagascar, equatorial western Indian Ocean, subtropical southern Indian Ocean, and the western Pacific.
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 Coral Sea. Below-normal precipitation was observed over much of tropical-subtropical Asia including Borneo and western Indonesia. Below-normal precipitation was also observed over the equatorial Indian Ocean and the subtropical southern hemisphere except the Coral Sea.
Rainfall Patterns: Last 5 Days During the past week, the Australian monsoon rainfall was overall below normal.
Rainfall Time Series over 5x5 lat-lon boxes • *This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. • Rainfall has been continuously above normal over much of northern Australia and the maritime continent, consistent with the general features associated with La Nina. However, the Australian monsoon rainfall was below normal in the past weeks (lower panel). • Persistently dry condition was observed over southern India (middle panel). • The precipitation over much of the East Asian winter monsoon region became above normal after a dry season (upper panel).
Atmospheric Circulation The lower-tropospheric circulation was marked by two major features: the anomalous cyclonic pattern over the tropical central-eastern southern Indian Ocean and the intensified trade wind over the western Pacific Ocean.
NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Week 1 & Week 2 Week-1 Week-2
Predictions of Australian Monsoon • Upper panel: Australian monsoon index (Hung and Yanai 2004) defined as mean U850 over 15S-2.5S, 110E-150E. The NCEP Global Forecast System predicts that the Australian monsoon circulation will be weaker than normal in the next week. • Lower panel: Correlation between precipitation and the Australian monsoon index (Hung and Yanai 2004; shading) and regression of 850-mb winds on the monsoon index (vectors) for March.
Summary • During the past week, the rainfall over the Australian monsoon region and Madagascar was overall below normal. • The Australian monsoon tends to be weaker than normal in the next two weeks.
