NOAA-CoRP Symposium, Aug 15-18, 2006 Radiative Transfer Modeling for Simulating GOES-R imagery...

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


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


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.


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


Observational Operator Highlights

Radiative transfer models

Infrared

Delta-Eddington scheme

Visible and near-infrared

Plane-parallel version of Spherical Harmonics Discrete Ordinate Method (SHDOMPP)


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


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


Comparison of simulations from 3.9 µm with 10.35 µm of GOES-R ABI

3.9 µm 10.35 µm


Comparison of observations from Ch 3 (6.7 µm) of GOES-12 with Simulations

Observations Modeled

May 8, 2003: thunderstorm outbreak


Comparison of observations from Ch 4 (10.7 µm) of GOES-12 with Simulations



Screened thunderstorm

Brightness temperature <243 K

observation model



Histograms of observed and modeled brightness temperatures

a b

c d

Observations Model


Percentile scatter plot of 1 hour of observed versus modeled brightness temperatures

Percentile

Bri

gh

tnes

s te

mp

erat

ure


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.


Questions?

Comments……….

NOAA-CoRP Symposium, Aug 15-18, 2006 Radiative Transfer Modeling for Simulating GOES-R imagery...

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