Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP May 23, 2011 For more information, visit: http://www.cpc.ncep.noaa.gov/products/Global_Monsoons/Asian_Monsoons/Asian_Monsoons.shtml 1 Outline • Recent Evolution and Current Conditions • Monsoon Prediction • Summary • Climatology 2 Precip Patterns: Last 90 Days Note: Occasionally when the update date of the land+ocean precip maps are not close enough to the release date of this weekly scheduled monsoon ppt. we use the more recent land -only precip maps. During the past 90 days, precipitation continues to below normal over eastern and southeastern coastal China, near about normal over subtropical maritime southeast Asia, and above normal over northern Australia. The summer monsoon is on its westward transition to the Indian subcontinent. 3 Precip Patterns: Last 30 Days Please see Note in Slide three. The 30-day precipitation accumulation is still seriously deficient over interior and coastal eastern China around 30N, but much improved over southeastern coastal China. Precipitation over coastal and interior eastern Australia is also highly deficient. 4 Precip Patterns: Last 7 Days Please see Note in Slide three. If land only maps are used, this map corresponds to the last seven days. During the last seven days, southwest monsoon is established over Indochina peninsula and appears to be on its way towards Indian region. 5 Rainfall Time Series over 5x5 lat-lon boxes Note: This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. The time series of precipitation over the various regions is quite consistent with the spatial maps shown earlier, even though as noted above, the rainfall data sets are from different sources and are processed differently. 6 Atmospheric Circulation While the summer monsoon over IndoChina area is active and somewhat normal, the monsoon establishment of the Arabian Sea/Bay of Bengal region appear to be delayed or weak due to the anomalous high pressure in the area. NCEP’s GFS model forecast for the next two weeks (next slide) also suggests a possible delayed onset, or a weakened monsoon circulation over peninsular India region. 7 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) defined as U850 (020ºN, 40-110ºE) – U200 (0-20ºN, 40-110ºE). Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that the Webster-Yang monsoon index will be very deficient in the upcoming 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 March. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 9 Prediction of South Asian Monsoon Index Upper panel: South Asian monsoon index (Goswami et al. 1999) ) defined as v850 (1030ºN, 70-110ºE) – v200 (10-30ºN, 70-110ºE). Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the Southeast Asian and northwestern Pacific monsoon index will be at or slightly below normal level 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 March Green (brown) shading indicates increase (decrease) in rainfall associated with strong 10 monsoon. Prediction of East Asia – NW Pacific Monsoon Upper panel: East Asia – Western North Pacific (EAWNP) monsoon index (Wang et al. 2008) defined as U850 (5-15ºN, 40-80ºE) – U850 (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 Southeast Asian and northwestern Pacific monsoon index will be at or slightly above normal level in the next two weeks. 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 March Green (brown) shading indicates increase (decrease) in rainfall associated with strong 11 monsoon. Summary • During the past 90 days, precipitation continues to be below normal over eastern and southeastern coastal China, near about normal over subtropical maritime southeast Asia, and above normal over northern Australia. The summer monsoon is on its westward transition to the Indian subcontinent. The 30-day precipitation accumulation is still seriously deficient over interior and coastal eastern China around 30N, but much improved over southeastern coastal China. Precipitation over coastal and interior eastern Australia is also highly deficient. • During the last seven days, while the summer monsoon over Indochina area is active and somewhat normal, the monsoon establishment in the Arabian Sea/Bay of Bengal region appear to be delayed or weak due to the anomalous anticyclonic circulation in the area. NCEP’s GFS model forecast for the next two weeks also suggests a possible delayed onset, or a weakened monsoon circulation over peninsular India region. The IMD (India Met. Dept.) is predicting a normal monsoon onset over Kerala around the end of May. 12 Demise of the Asian Monsoon 13 Onset of the Australian Monsoon 14 Climatology 15