Download Convection over China

Convection over China
-ISCCP DX Data analysis result
EAS6792
Deng Xueyuan
Content
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Motivation
Data and Method
Convection in Eastern Asia
Comparison between ISCCP&MM5
Motivation
Influence of convection on tracers concentrations
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Transport
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Clouds
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C shape vertical concentration profile
Photolysis
Others
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Rainout
Data
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ISCCP DX
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International Satellite Cloud Climatology Project
(ISCCP)
Resolution: 30km mapped pixel, 3 hr, individual
satellites
Data download from ftp://eclipse.ncdc.noaa.gov
Data parameter list:
ftp://isccp.giss.nasa.gov/pub/documents/dx.titles
NCEP/NCAR Reanalysis data
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Geopotential height, precipitation rate, ω
Method
Judge of convective cloud from ISCCP data
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Visible optical thickness
Cloud top : temperature, height, pressure
Here I use both
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visible optical thickness() >23
cloud top temperature( T) T<240K (about 8 km)
Convection in East Asia
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Relationship between Circulation and
convection
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Convection and circulation in eastern Asia
Winter
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Circulation
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Mongolia High Pressure
cold air controlled most part of
china.The Tibet plateau is
colder which make the cold
height stronger. Weather will
be cold and dry unless when
the cold air move to the
southern part and meet with
warm air.
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Yunnan
Cold air and warm air meet
there, which will favor the
convection.
200401 mean sea level pressure
Convective cloud fraction from ISCCP (left)
ω in 700 hPa ( right upper)
Precipitation rate (mm/day) (right bottom)
Spring
Circulation
 Mongolia Height move
to the west and
becomes weak
 Low pressure system
in south Asia and
pacific height grows
 Tropical warm moisture
air move to the south
part of China
200404 mean sea level pressure
Convective cloud fraction from ISCCP (left)
ω in 700 hPa ( right upper)
Precipitation rate (mm/day) (right bottom)
Summer
Circulation
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200407 mean sea level pressure
Mongolia Height
disappear, pacific height
and India low appear
Tibet become heat
source, which enhance
the low pressure system
Northern part of China
goes into rain season
and southern part also
rain a lot b/c of the
tropical system
Convective cloud fraction from ISCCP (left)
ω in 700 hPa ( right upper)
Precipitation rate (mm/day) (right bottom)
Fall
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200407 mean sea level pressure
Reverse of
Spring
Rain in west
south part
Convective cloud fraction from ISCCP (left)
ω in 700 hPa ( right upper)
Precipitation rate (mm/day) (right bottom)
Asian Monsoon
East Asian Monsoon
India Monsoon
West Pacific
Monsoon
Typhoon
Monsoon set up
area
（Weijin Li et al 2003）
Summary
1 season change
more convection in summer
less convection in winter
2 Spatial difference
more convection in southern
part
less convection in northern
part
3 Rain belt can be see
from the convective
cloud
4 More high cloud over
Tibet
ISCCP
MM5
NCEP/NCAR Reanalysis data
precipitation rate (mm/day)
ω at 700mb