Sensitivity of Input Geophysical Parameters on Radiative Transfer Model at Water Vapor Sounding Frequencies and Possible Impact on Radiometer Calibration

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Overview  •  GMI sounder channel intercomparison

w.r.t Ø MT SAPHIR Ø METOP-A MHS Ø METOP-B MHS Ø  NOAA 18 MHS and Ø  NOAA 19 MHS

•  Used Collocated sensor data and CFRSL Double Difference Technique

•  Colocation done using two different approaches

Ø  Binned Average Ø  Individual Matchup

•  Used GDAS data as input geophysical parameter to the forward radiative transfer model (RTM).

•  Intend to check the sensitivity of the RTM to

Ø  Input WV profile Ø  Different emissivity model Ø  Different absorption model

Data  Filters  •  Convection Filter : i.e. each channel should be at least 1K warmer than the one above and eliminates any matched pair for which any of the channel observed and simulated Tb’s differ more than 10 K.

•  0< CLWGDAS < 0.1

•  Land mask is applied.

• Used QA flags in the sensor data file.

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Theoretical values are obtained modeling the entire bandwidth with steps= 100 MHz Input  Sensi3vity  Analysis  

 

Dr. James Wang provided some retrieved profile for a small sample of matchups, which are used for WV input sensitivity analysis.  

Acknowledgement:    This  work  is  supported  by  NASA  award  #  NNX13AH48G      

Summary:  GMI prelim. inter-comparison shows some bias w.r.t other sounders. Single differences are sensitive to input WV profile and emissivity model.  Next  Steps,  continue sensitivity analysis using different sets of input like ERA interim analysis, radiosonde observations and also use different absorption and emissivity model.    

#  207  Saswati Datta1, W. Linwood Jones, Hamideh Ebrahimi, Ruiyao Chen, Andrea Santos-Garcia, Viviene Payne, T. Wilheit and James Wang

1 contacting author: sdatta@dniconsultants.com  

Two  different  surface  emissivity  models,  Elsaesser  and  RSS,  compared.