Geophysical Parameter Retrieval from INSAT Data

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Geophysical Parameter Retrieval from INSAT Data
Pradip K Pal Meteorology and Oceanography
Group Space Applications Centre
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Current Indian Geostationary Meteorological
Satellites
93.5o
74o
83o
INSAT-3A
Kalpana-1
INSAT-2E
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INSAT 3A Kalpana-1
Payload (i) VHRR CCD camera in INSAT-2E,
3A (ii) VHRR in Kalpana-1

• VHRR Bands (µm)
• Visible 0.55 0.75
• Water vapour 5.70 7.10
• Thermal Infra Red 10.5 12.5
• Resolution (km) 2 X 2 for Visible
• 8 X 8 for WV TIR

• CCD Camera Bands (µm)
• Visible 0.62 0.68
• Near Infra Red 0.77 0.86
• Short Wave Infra Red 1.55 1.69
• Resolution (km) 1 X 1 for all bands

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INSAT - 3D
6 Channel IMAGER
19 Channel SOUNDER

• Spectral Bands (µm)
• Short Wave Infra Red Six bands
• Mid Wave Infra Red Five Bands
• Long Wave Infra Red Seven Bands
• Visible One Band
• Resolution (km) 10 X 10 for all
  
  bands

• Spectral Bands (µm)
• Visible 0.55 - 0.75
• Short Wave Infra Red 1.55 - 1.70
• Mid Wave Infra Red 3.80 - 4.00
• Water Vapour 6.50 - 7.00
• Thermal Infra Red 1 10.2 - 11.3
• Thermal Infra Red 2 11.5 - 12.5
• Resolution 1 km for Vis, SWIR
• 4 km for MIR, TIR
• 8 km for WV

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INSAT-3A/ Kalpana VHRR Derived Products

• Atmospheric Motion Vector
• Outgoing Longwave Radiation
• Sea Surface Temperature
• Upper Tropospheric Humidity
• Rainfall

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Upper Tropospheric Humidity(UTH)
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Upper Tropospheric Humidity

• UTH() cos(?).exp(a b.Tb6.7)
• is the satellite zenith angle of the
  corresponding pixel, and
• a and b are the coefficients derived using
  radiative transfer model simulations.

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Atmospheric Motion Vectors(AMV)
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Satellite Derived Motion Fields BASIC METHODOLOGY
Image acquisition
Highly Critical
Automatic Rergistration
Coherence Local Gradients
Target Selection
Highly Critical
Target Height Assignment
Target Tracking
Quality Control
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Upper level winds from Kalpana and their
comparison with Meteosat operational winds
(02-Nov-2004, 1300 IST)
15 ms-1
(No Smoothening)
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COMPARISON OF DERIVED WINDS WITH METEOSAT
OPERATIONAL PRODUCTS
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Outgoing Longwave Radiation(OLR)
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• Methodology for OLR Computation
• Broad band equivalent temperature (Tf ) is
  computed from Tw using the relation.
• TfTw (abTw) -------------------(1)where a
  and b are regression coefficients dependent on
  the sensor.
• Outgoing Longwave Radiation OLR s Tf 4

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Comparison of Outgoing Longwave radiation (OLR)-
(W/m2) from INSAT-3A and NOAA, for 15 Oct. 2004.
 
 
 
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Fig-4 Diurnal variation of OLR (W/m2 ) from INSAT
3A 8th October 2004
 
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RAINFALL FROM INSAT-3A AND KALPANA
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Methodology
An estimation method followed from Arkin was
used which has the regression equation as
R(mm/day) ? 3 mm h-1 X frac X hours
where R is the rainfall estimate in millimeters
frac is the fractional coverage of cloud-top
temperature lt 235K for the desired 2.5
degree latitude/longitude region and hours
indicate the number of hours in the observation
period.
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A Comparison of INSAT-3A and TRMM-Merged Rainfall
TRMM Merged Rainfall 11.00 Hrs 14 Oct. 2004

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Comparison of some of the KALPANA and TRMM
Observations
                                                 
                                       
 
Rainfall from KALPANA and TRMM
KALPANA
TRMM
 
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Sea Surface Temperature(SST)
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The current SST retrieval algorithm involves only
single channel thermal window data of INSAT-3A
and Kalpana satellite and hence there is no
explicit water vapour correction applied. SST
a bTb Therefore, the accuracies of SST
retrieval heavily depend upon the intervening
TWV(errors 4 to 5 K) In case of INSAT-3D,
typically SST a bT11 c(T11-T12)
d(T11-T12)(T11-T12) where T11-T12 term is
proportional to TWV.
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Improving Cloudfree fields through multiple
images in 1-day
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INSAT-3D Meteorological Parameter Retrieval
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INSAT-3D ImagerMeteorological Parameters

• Sea Surface Temperature (SST)
• Split window Thermal IR (Ch5 Ch6)
• Atmospheric Motion Vectors (AMV) 3 Levels
• VIS, IR WV (Ch1, Ch4, Ch5, Ch6)
• Outgoing longwave radiation (OLR)
• Conversion of narrow band radiances to broad band
  radiances (Ch5 and Ch6)
• Quantitative Precipitation Estimates (QPE)
• IR VIS

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INSAT-3D Sounder
Meteorological Parameters

• Vertical Profiles of
• Temperature (15 levels upto 10 hPa)
• Humidity (upto 300 hPa)
• Total Ozone (Ch9)

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Retrieval Procedure (Sounder)
Physically based method

• Initial guess profile for temperature and
  humidity
• Climatology, or Numerical Model Analysis
• Surface analysis 1000 hPa Geopotential Height
• Surface air temperature
• Surface humidity
• Forward Simulation of Sounder channel Radiances
  using RT model
• Radiances Inversion for parameter retrieval
• Comparison of simulated radiances with sounder
  radiances
• Adjusting the guess profiles to match the
  simulated radiances with the observed radiances
  for all channels

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• Statistical Method
• Generation of database for sounder radiances from
  a large number of radiosonde/analysis profiles of
  atmospheric temperature and humidity as a
  function of different seasons/ regions.
• Estimate of best temperature/ Humidity profile
  using sounder channels radiances from the
  database based on statistical/ neural network/
  Genetic techniques.

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RTTOV-7 (Eumetsat)

• Fast Radiative Transfer Model
• State vector Atmospheric profile (43 levels) of
  temperature, variable gas (H2O, O3), cloud and
  surface properties.
• Spectral range 3-20?m and 10-200 GHz

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Surface Specific Humidity (g/Kg) - NCEP Analysis
RTTOV input parameter taken from NCEP
Analysis Surface Pressure, Surface Temperature,
Surface Air Temperature and Specific Humidity at
2m height, Temperature and Humidity profiles
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FUTURE WORK

• Algorithms for meteorological parameters from
  Imager channels are being fine tuned for improved
  retrieval.
• Inversion technique and retrieval procedure for
  Sounder channels are being developed.

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Thank You
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Radiative Transfer Equation
Radiances reaching at the Top
is tranmittance between p1 p2
is weighting function
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Projection of Earth Viewed from finite Distance
Vertical Perspective Projection
P
P1
N
?o ?o
h
?
S
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INSAT-3A
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MAP OVERLAY ON A PART OF KALPANA-VISIBLE
556, 774
83.56 E, 17.92 N
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INSAT WV,IR data
Calibration Table
WV, IR Brightness Temp.
Cloud elimination lt 270 K
Co-eff from RT simulation
UTH.
Geolocation file
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Early Attempts for retrieval of Water-Vapor winds
Meteosat- NW Sector 02-NOV-2004
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Fig 3Outgoing longwave radiation (W/m2) derived
from INSAT-3A (11-15 October, 2004)

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Rainfall from KALPANA and TRMM
TRMM
KALPANA