The AsianAustralian Monsoon System Recent Evolution Current Status

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The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate

The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP 12 October 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

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

Rainfall Patterns: Last 90 Days During the past 90 days, below-normal monsoon rainfall was

Rainfall Patterns: Last 90 Days During the past 90 days, below-normal monsoon rainfall was observed over India, Indo. China peninsula, southern China, Northeast China, and the East China Sea. Belownormal rainfall was also observed over Indonesia, Malaysia, tropical southern Indian Ocean, and eastern Australia. Rainfall was above normal over the eastern Arabian Sea, Bangladesh, Myanmar, northern Bay of Bengal, the South China Sea, Philippines, the Philippine Sea, the western Pacific, and equatorial eastern Indian Ocean. 3

Rainfall Patterns: Last 30 Days During the past 30 days, monsoon rainfall was below

Rainfall Patterns: Last 30 Days During the past 30 days, monsoon rainfall was below normal over East Asia and Indonesia. Below-normal rainfall was also found over part of India, Sri Lanka, and much of the tropical Indian Ocean. On the contrary, rainfall was above normal over the northern Bay of Bengal, the South China Sea, northern Philippines, the Philippine Sea, and the western Pacific east of 140 E. 4

Rainfall Patterns: Last 5 Days Rainfall was above normal over northern India, Bangladesh, northern

Rainfall Patterns: Last 5 Days Rainfall was above normal over northern India, Bangladesh, northern Bay of Bengal, northern Philippines, and south of Japan. Below-normal rainfall was observed over southern India, central tropical Indian Ocean, Indo-China peninsula, southern China, and the Philippine Sea. 5

Rainfall Time Series over 5 x 5 lat-lon boxes *This unified land-only daily precipitation

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. • Upper panel: Impact of typhoon has significantly enhanced the post monsoon rainfall over the Philippines. • Middle panel: The accumulated rainfall over the Indo-China peninsula has been constantly below normal during the past season. • Bottom panel: Southern India experienced heavy late monsoon rainfall. 6

Atmospheric Circulation Large-scale tropical monsoon flow was stronger than normal, with an anomalous cyclonic

Atmospheric Circulation Large-scale tropical monsoon flow was stronger than normal, with an anomalous cyclonic pattern (centered over India and Philippines-Taiwan) over southern Asia and adjacent oceans. 7

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

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

Prediction of Large-Scale Monsoon Circulation Upper panel: Webster-Yang monsoon index (Webster and Yang 1992)

Prediction of Large-Scale Monsoon Circulation Upper panel: Webster-Yang monsoon index (Webster and Yang 1992) defined as U 850 (020ºN, 40 -110ºE) – U 200 (0 -20ºN, 40 -110ºE). Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that the large-scale monsoon circulation over tropical Asia will be weaker than normal in the next two weeks. Lower panel: Correlation between rainfall and Webster-Yang monsoon index (Webster and Yang 1992; shading) and regression of 850 -mb winds on the monsoon index (vectors) for October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 9

Prediction of South Asian Monsoon Circulation Upper panel: South Asian monsoon index (Goswami et

Prediction of South Asian Monsoon Circulation Upper panel: South Asian monsoon index (Goswami et al. 1999) defined as V 850 -V 200 over 10 -30ºN, 70 -110ºE. Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that the monsoon-type circulation over South Asia will be weaker than normal in the next two weeks. Lower panel: Correlation between rainfall and South Asian monsoon index (Goswami et al. 1999; shading) and regression of 850 -mb winds on the monsoon index (vectors) for October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 10

Prediction of East Asian Monsoon Upper panel: East Asian monsoon index (Li and Zeng

Prediction of East Asian Monsoon Upper panel: East Asian monsoon index (Li and Zeng 2002; GRL). Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the East Asian monsoon circulation will be near or weaker than normal. Lower panel: Correlation between rainfall and East Asian monsoon index (Li and Zeng 2002; shading) and regression of 850 -mb winds on the monsoon index (vectors) for October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 11

Prediction of East Asia – NW Pacific Monsoon Upper panel: East Asia – Western

Prediction 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 (20 -30ºN, 70 -90ºE). Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the EAWNP monsoon circulation will continue to be near or stronger than normal. Lower panel: Correlation between rainfall and East Asia – Western North Pacific monsoon index (Wang et al. 2008; shading) and regression of 850 -mb winds on the monsoon index (vectors) for October. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 12

Summary • Rainfall was above normal over northern India, Bangladesh, northern Bay of Bengal,

Summary • Rainfall was above normal over northern India, Bangladesh, northern Bay of Bengal, northern Philippines, and south of Japan. Below-normal rainfall was observed over southern India, central tropical Indian Ocean, Indo-China peninsula, southern China, and the Philippine Sea. • The NCEP Global Forecast System predicts that, in the next two weeks, monsoon circulation will be mainly weaker than normal over southern Asia, with near normal condition over Southeast Asia. 13

Retreat of the Asian Monsoon 14

Retreat of the Asian Monsoon 14

Climatology 15

Climatology 15