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

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
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Outline
• Recent Evolution and Current Conditions
• Monsoon Prediction
• Summary
• Climatology
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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.
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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.
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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.
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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.
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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.
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NCEP/GFS Model Forecasts
Bias-Corrected Precip. Anom. for Weak 1 & Week 2
Week-1
Week-2
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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.
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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
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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
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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.
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Demise of the Asian Monsoon
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Onset of the Australian Monsoon
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Climatology
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