Download
1 / 15
150 likes | 160 Views
This report provides an overview of the recent evolution and current conditions of the Asian-Australian monsoon system, as well as predictions for the future. It includes information on precipitation patterns, atmospheric circulation, and monsoon indices for different regions. The report predicts continued above-normal rainfall in Eastern Australia in the next two weeks.
E N D
The Asian-Australian Monsoon System: Recent Evolution, Current Status and Prediction Update prepared by Climate Prediction Center / NCEP January 3, 2011 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
Precip Patterns: Last 90 Days During the past 90 days, except over the southern coastal land regions of China, precipitation has been well above normal over much of southern, south eastern Asia, and Australia consistent with the ongoing La Nina conditions.
Precip Patterns: Last 30 Days (Pls. see note at top[ in previous slide) During the past 30 days, convection associated with the Northeast “winter” brought copious rainfall to large parts of particularly northern and eastern Australia, where the received rainfall is as much as over 250 % of the normal.
Precip Patterns: Last 5 Days (Pls. see note at top[ in previous slide) During the past week, much of eastern Asia received below normal rainfall. However, north eastern Australia is beginning to receive above normal rainfall.
Rainfall Time Seriesover 5x5 lat-lon boxes *This unified land-only daily precipitation dataset is different from the CMAP dataset used in the previous three spatial maps. Over a large part of Southeast Asia, the accumulated rainfall has been persistently above average in the past three months. 6
Atmospheric Circulation The active southern hemisphere monsoon trough over Eastern Australia has brought record rainfall and associated flooding in that regions. The NCEP GFS forecast for the next two weeks indicates continued above normal rainfall in this region..
NCEP/GFS Model Forecasts Bias-Corrected Precip. Anom. for Weak 1 & Week 2 Week-1 Week-2
Prediction of Large-Scale Monsoon Circulation Upper panel: Webster-Yang monsoon index (Webster and Yang 1992) defined as U850 (0-20ºN, 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 continue to be above 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 January. Green (brown) shading indicates increase (decrease) in rainfall associated with strong 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 around normal level. 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 January. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon.
Prediction of Australian Monsoon Upper panel: Australian monsoon index (Hung and Yanai 2004) defined as U850 averaged over 2.5ºS-15ºS, 110-150ºE. Positive (negative) values indicate strong (weak) than normal monsoon. The NCEP Global Forecast System predicts that, in the next two weeks, the Australian monsoon circulation will be at or slightly above normal. Lower panel: Correlation between rainfall and Australian monsoon index (Hung and Yanai 2004; shading) and regression of 850-mb winds on the monsoon index (vectors) for December. Green (brown) shading indicates increase (decrease) in rainfall associated with strong monsoon. 11
Summary • Over the past 90-, and 30-days, above-average rainfall was observed over much of Southeast Asia and North and eastern Australia. The active southern hemisphere monsoon trough over Eastern Australia has brought record rainfall and associated flooding in that region, particularly in the last few weeks. The NCEP Global Forecast System indicates continued above normal rainfall in this region for the next two weeks.
