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NOAA-CoRP Symposium, Aug 15-18, 2006
Radiative Transfer Modeling for Simulating GOES-R imagery
Manajit Sengupta1
Contributions from:
Louie Grasso1, Jack Dostalek1, Dan Lindsey2 and Mark DeMaria2
1. CIRA/Colorado State University,
2. NOAA/NESDIS Fort Collins, CO
NOAA-CoRP Symposium, Aug 15-18, 2006
Methodology for simulating GOES-R imagery
Mesoscale model output
Inputs for radiative transfer
Compute gaseous absorption Compute cloud optical properties
Compute GOES-R radiance or reflectance
Forward Observational Operator
NOAA-CoRP Symposium, Aug 15-18, 2006
Mesoscale Model components for more accurate Radiative Transfer computations
RAMS Numerical Cloud Model Non-hydrostatic cloud model developed at CSU
Sophisticated two-moment cloud microphysics
mass mixing ratio and number concentration are prognosed
aggregates, graupel, hail, pristine ice, rain, snow, and cloud water
Two-way interactive nested grids
Four grids: 50 km, 10 km, 2 km (GOES-R) and 400 m (NPOESS).
RAMS initial condition from NCEP ETA model analysis
Run cloud model and use output as input to an observational operator to generate synthetic GOES-R satellite observations for different channels.
NOAA-CoRP Symposium, Aug 15-18, 2006
OPTRAN (part of JCSDA CRTM) used to calculate gaseous absorption
GOES-R ABI coefficients obtained from JCSDA (3.9 – 13.3µm)
Modified anomalous diffraction theory (MADT) for cloud optical properties
assumes gamma distribution for the calculation of a mean diameter
single scatter albedo, extinction coefficient, asymmetry factor for 7 hydrometeor types
weighting by hydrometeor number concentration from RAMS for bulk optical properties
Other possible methods for computing optical properties
Mie theory for water drops
Ice scattering tables from explicit computations.
Observational Operator Highlights
NOAA-CoRP Symposium, Aug 15-18, 2006
Observational Operator Highlights
Radiative transfer models
Infrared
Delta-Eddington scheme
Visible and near-infrared
Plane-parallel version of Spherical Harmonics Discrete Ordinate Method (SHDOMPP)
NOAA-CoRP Symposium, Aug 15-18, 2006
Case Studies
May 8-9, 2003 :Severe thunderstorm outbreak over Oklahoma and Kansas.
September 30-October 4, 2002: Hurricane Lili
February 12-14, 2003: Lake effect snow
NOAA-CoRP Symposium, Aug 15-18, 2006
Synthetic 2 km GOES-R ABI Bands 7-168 May Severe Weather Case
3.9 µm 6.2 µm 7.0 µm 7.3 µm
8.5 µm 9.6 µm 10.35 µm 11.2 µm
12.3 µm 13.3 µm
NOAA-CoRP Symposium, Aug 15-18, 2006
Comparison of simulations from 3.9 µm with 10.35 µm of GOES-R ABI
3.9 µm 10.35 µm
NOAA-CoRP Symposium, Aug 15-18, 2006
Comparison of observations from Ch 3 (6.7 µm) of GOES-12 with Simulations
Observations Modeled
May 8, 2003: thunderstorm outbreak
NOAA-CoRP Symposium, Aug 15-18, 2006
Comparison of observations from Ch 4 (10.7 µm) of GOES-12 with Simulations
Observations Modeled
NOAA-CoRP Symposium, Aug 15-18, 2006
Screened thunderstorm
Brightness temperature <243 K
observation model
Observations Modeled
NOAA-CoRP Symposium, Aug 15-18, 2006
Histograms of observed and modeled brightness temperatures
a b
c d
Observations Model
NOAA-CoRP Symposium, Aug 15-18, 2006
Percentile scatter plot of 1 hour of observed versus modeled brightness temperatures
Percentile
Bri
gh
tnes
s te
mp
erat
ure
NOAA-CoRP Symposium, Aug 15-18, 2006
Conclusions
Mesoscale cloud model should contain 2 moment microphysics for cloud radiance/reflectance simulations.
For simulation of all channels gaseous absorption coefficients should be available for OPTRAN.
Optical properties for ice crystals and water droplets in clouds should be accurately computed.
Radiative transfer modeling should be accurate but reasonably quick.
Our current capabilities allow us to simulate different weather events.
NOAA-CoRP Symposium, Aug 15-18, 2006
Questions?
Comments……….