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
February 22, 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
•* WE continue to have technical difficulties with
the routine updates of many of the products and
Figures used here and we regret for the
inconvenience this may cause to some of the
users.
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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, as can be seen from the total,
anomalous and percentile maps over land, precipitation has
been generally near, above or much above normal over
much of the monsoon region, except over southern, eastern
China, the middle east and over parts of Papua New
Guinea.
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Precip Patterns: Last 30 Days
Please see Note in Slide three.
Even though the 90 day accumulated precip
has been above normal over much of the
season over large parts of the monsoon
region, 30-day accumulation is beginning to
show some serious deficiencies over
eastern Australia and in the interior central
regions. South eastern China continues the
dryness developed earlier.
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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, monsoon rainfall was much below normal
over southern Malaysia, maritime Indonesian continent, and over
Queensland, Australia. However, during the past week, rainfall was
much above normal along northwestern and western Australia, due to
tropical storm/cyclone Carlos, which is leaving the area and heading
west towards Indian Ocean.
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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 precip data sets are
from different sources and are processed differently.
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Atmospheric Circulation
Overall, the weakened monsoon circulation over the region this past week is
quite consistent with the below normal rainfall over much of the monsoon
region except for the cyclonic circulation over northwestern Australia
associated with Tropical Storm/Cyclone Carlos.
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NCEP/GFS Model Forecasts
Bias-Corrected Precip. Anom. for Weak 1 & Week 2
Week-1
Note: The NCEP/GFS based Forecast
maps are not updated this week due to
technical difficulties. The maps shown
here are from prev. week.
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 suggests above normal
rainfall over the region.
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.
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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 slightly above
normal rainfall in the upcoming 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 January. Green
(brown) shading indicates
increase (decrease) in rainfall
associated with strong
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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 the Australian monsoon
circulation (over northern Australia)
indicates above normal rainfall in the
upcoming week followed by a return to
normal conditions in the second
week./
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 associated11with
strong monsoon.
Summary
• During the past 90 days, as can be seen from the total,
anomalous and percentile maps over land, precipitation has
been generally near, above or much above normal over
much of the monsoon region, except over southern, eastern
China, the middle east and over parts of Papua New Guinea.
However, the 30-day accumulation is beginning to show
some serious deficiencies over eastern Australia and in the
interior western regions. South eastern China continues the
serious dryness developed earlier.
• During the past week, Tropical Storm/Cyclone Carlos brought
above normal rainfall over northern/western Australia.
NCEP’s GFS model is again predicting slightly enhanced
precipitation over the same region in the upcoming week.
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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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