Combined use of OMI, MODIS and CALIPSO observations for characterization of aerosol absorption

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Combined use of OMI, MODIS and CALIPSOobservation
s for characterization of aerosol absorption
Omar Torres, Zhong Chen Hampton University,
Hampton, Va Changwoo Ahn SSAI Inc, Lanham,
MD S.K. Satheesh, L. Remer, P.K.Bhartia Goddard
Space Flight Center, Greenbelt, MD
EOS AURA Science Team Meeting 27-30 October 2008,
Columbia, Maryland
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Aerosol-sensing instruments in the A-train
NPP-VIIRS and Glory-APS will join the A-train
NPP
OMI, PARASOL, Calipso, MODIS,AIRS are currently
operational
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Aerosol-Sensing Capabilities of A-train
Instrumentation
Sensor Optical Depth Particle Size Real Ref. Index SSA Particle Shape Aerosol Layer Height.
MODIS (VIIRS) ? ? ?
PARASOL ? ? ?
OMI ? ?
CALIPSO ? ? ?(VD,NT)
AIRS ?(NT)
Glory-APS ? ? ? ? ?
Caveats -Not all sensors have daily global
coverage -Land-ocean differences in retrieval
accuracy -Differences in wavelength
? Validated ? Unverified ? Planned
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OMI Near UV Retrieval Procedure
The relationship between the observed radiances
at 354 and 388 nm in the presence of absorbing
aerosols is mainly driven by three aerosol
parameters Total Aerosol Load (AOD) Single
Scattering Albedo (SSA) Aerosol Layer
Height Since the Algorithm only uses two pieces
of information, it is necessary to assume the
value of one of the aerosol parameters to
retrieve the other two. Standard Near-UV
algorithm makes an assumption on the aerosol
layer height.
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OMI Near-UV Retrieval Products
1. Set of AOD/SSA for 5 different assumptions on
aerosol layer height
0.0 AOD0.0 SSA0.0
1.5 AOD1.5 SSA1.5
3.0 AOD3.0 SSA3.0
6.0 AOD6.0 SSA6.0
10.0 AOD10.0 SSA10.0
2. Most likely AOD and SSA values are chosen
based on a choice of aerosol layer height from
climatological considerations Both the height
dependent set of retrievals as well as the
recommended solution are reported in the Level-2
Product.
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OMI Retrieved Dust Properties (March 9-2007)
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Evaluation of extinction AOD using AERONET
observations
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Seasonal Averages of Aerosol Absorption (OMI 2006)
Single Scattering Albedo
DJF
MAM
JJA
SON
Absorption Optical Depth
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Combined OMI-MODIS retrieval Use
MODIS retrieved AOD as input to the OMI retrieval
and return the aerosol height and single
scattering albedo
z1 AOD1 ?o1
z2 AOD2 ?o2
z3 AOD3 ?o3
z4 AOD4 ?o4
z5 AOD5 ?o5
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Ascension Island
First, can MODIS AOD retrieval (466 to 2130 nm)
be extrapolated to the UV wavelength of 388 nm?
MODIS extrap 380 nm AOD
Simple linear extrapolation (log-log) is good,
but not adequate. Deviations from linear can be
explained by the difference in AOD at 440 and
870 nm
Linear extrap
AERONET measured 380 nm AOD
AERONET - MODIS AOD 380
Satheesh et al. (JGR, accepted)
AOD470 -AOD870
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Linear extrapolation
With curvature correction
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Areas of study
Satheesh et al. (to be submitted)
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Atlantic Ocean
Arabian Sea
0.15
0.3
All data
AOD380 OMIstd - OMIMOD
?o380 OMIstd - OMIMOD
-0.03
-0.1
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Height (km) OMIstd - OMIMOD
-3.5
Months in 2006
Months in 2006
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Validating height retrieval In Arabian Sea
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Summary of Results
Monthly mean values of AOD, ?o and layer height
for the months of Jan 06 and Mar 06 for the 3
regions
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OMI Calipso Synergy, March 9, 2007
Height (km)
5
0
MODIS RGB
OMI, Calipso orbital coverage
OMI
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OMI Calipso ,Synergy, March 9, 2007 (2)
AOD_cor
AI
AOD_std
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Detection of Aerosols above clouds A unique
near-UV capability
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Summary
The unprecedented observational simultaneity of
the A-train presents new opportunities for more
accurate measurements of aerosol
properties optical depth, particle size and
information on shape, single scattering albedo
and aerosol layer height. Preliminary results on
the combined use of MODIS-OMI and Calipso-OMI
retrievals illustrate the great potential of
A-train retrieval capabilty of the A-train.
Current and Future Work Combined
OMI-MODIS application will be extended over land.
Calipso will be used for validation. An
improved near-UV algorithm capable of retrieving
aerosol absorption in the presence of clouds
is currently being developed.