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Validation of CrIMSS sounding products of 20120515. Cloud contamination and angle dependency Zhenglong Li, Jun Li, and Yue Li University of Wisconsin - Madison. Outline. CrIMSS sounding products are affected by cloud contamination viewing angle Validation using ECMWF
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Validation of CrIMSS sounding products of 20120515 Cloud contamination and angle dependency Zhenglong Li, Jun Li, and Yue Li University of Wisconsin - Madison
Outline • CrIMSS sounding products are affected by • cloud contamination • viewing angle • Validation using • ECMWF • CrIS radiance observations
Pre-processing • VIIRS Cloud fraction • VIIRS Cloud fraction: collocation of VIIRS cloud mask geolocation with CrIS SDR geolocation • Cloud fraction is calculated for each CrIS FOV by counting the cloudy VIIRS pixels • Simulated CrIS radiance by SARTA • CrIMSS T/Q/Tskin • CrIMSS(IP) O3 • UW hyperspectral land surface emissivity
CrIMSS overall quality flag - Ascending • Most of the retrievals are microwave only; thus may use CrIS spectrum validate CrIMSS sounding • Poor retrievals in high latitude areas
CrIS 11-micron Tb - Ascending • Exclude FORs with poor retrievals • Compare with CrIS cloud fraction in next slide
CrIS cloud fraction - Ascending • Exclude FORs with poor retrievals • Consistent with CrIS BT image in previous slide
Tskin: CrIMSS-ECMWF - Ascending • Exclude FORs with poor retrievals • Land is more prone to emissivity uncertainty • Appears to be geographically related with clouds • Appears to be related to satellite viewing angle between 40 S and 40 N
CrIS cloud fraction - Ascending • Exclude FORs with poor retrievals • Compare with T500 diff in next slide
T 500 hPa: CrIMSS-ECMWF - Ascending • Exclude FORs with poor retrievals • Appears to be geographically related with clouds in southern hemisphere • Appears to be related to satellite viewing angle between 40 S and 40 N
CrIMSS overall quality flag - Descending • Most of the retrievals are microwave only; thus may use CrIS spectrum validate CrIMSS sounding • Poor retrievals in high latitude areas
CrIS 11-micron Tb - Descending • Exclude FORs with poor retrievals • Compare with CrIS cloud fraction in next slide
CrIS cloud fraction - Descending • Exclude FORs with poor retrievals • Consistent with CrIS BT image in previous slide
Tskin: CrIMSS-ECMWF - Descending • Exclude FORs with poor retrievals • Appears to be geographically related with clouds • Appears to be related to satellite viewing angle between 40 S and 40 N
CrIS cloud fraction - Descending • Exclude FORs with poor retrievals • Compare with T500 diff in next slide
T 500 hPa: CrIMSS-ECMWF - Descending • Exclude FORs with poor retrievals • Appears to be geographically related with clouds in southern hemisphere • Appears to be related to satellite viewing angle between 40 S and 40 N
Clouds affect CrIMSS sounding - Ascending CF: cloud fraction Dash lines: bias Solid lines: STD Dev Clouds affect both precisions and accuracies, both T and Q Clouds affect precisions slightly more than accuracies Reference: ECMWF
Clouds affect CrIMSS sounding - Descending CF: cloud fraction Dash lines: bias Solid lines: STD Dev Clouds affect both precisions and accuracies, both T and Q Clouds affect precisions slightly more than accuracies Reference: ECMWF
Angle affects CrIMSS sounding - Ascending ANG: satellite viewing angle Dash lines: bias Solid lines: STD Dev Angle affects T more than Q Angle affects accuracies more than precisions All sky Reference: ECMWF
Angle affects CrIMSS sounding - Descending ANG: satellite viewing angle Dash lines: bias Solid lines: STD Dev Angle affects T more than Q Angle affects accuracies more than precisions All sky Reference: ECMWF
Angle affects CrIMSS sounding - Ascending An example of CrIS Tb spectrum in longwave CO2 band Upper atmosphere Lower atmosphere T angle dependency Combination of T/ε angle dependency Mean difference between CrIS obs and calc Reference: CrIS radiance obs Clear sky Ocean only
Angle affects CrIMSS sounding - Descending An example of CrIS Tb spectrum in longwave CO2 band Upper atmosphere Lower atmosphere T angle dependency Combination of T/ε angle dependency Mean difference between CrIS obs and calc Reference: CrIS radiance obs Clear sky Ocean only
Summary • CrIMSS sounding products agree with ECMWF reasonably well • Cloud presence slightly degrades the CrIMSS sounding products, both temperature and moisture, and both precisions and accuracies • CrIMSS temperature sounding products are slightly degraded with larger satellite viewing angle; more temperature bias • Suggest to add quality flags of cloud fraction and angle dependency