Sensitivity of Input Geophysical Parameters on Radiative ...
Transcript of Sensitivity of Input Geophysical Parameters on Radiative ...
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: [email protected]
Two different surface emissivity models, Elsaesser and RSS, compared.