Slide 1

Validation of CrIMSS sounding products of 20120515 Cloud contamination and angle dependency Zhenglong Li, Jun Li, and Yue Li University of Wisconsin - Madison

Slide 2

Outline CrIMSS sounding products are affected by cloud contamination viewing angle Validation using ECMWF CrIS radiance observations

Slide 3

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

Slide 4

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

Slide 5

CrIS 11-micron Tb - Ascending Exclude FORs with poor retrievals Compare with CrIS cloud fraction in next slide

Slide 6

CrIS cloud fraction - Ascending Exclude FORs with poor retrievals Consistent with CrIS BT image in previous slide

Slide 7

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

Slide 8

CrIS cloud fraction - Ascending Exclude FORs with poor retrievals Compare with T500 diff in next slide

Slide 9

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

Slide 10

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

Slide 11

CrIS 11-micron Tb - Descending Exclude FORs with poor retrievals Compare with CrIS cloud fraction in next slide

Slide 12

CrIS cloud fraction - Descending Exclude FORs with poor retrievals Consistent with CrIS BT image in previous slide

Slide 13

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

Slide 14

CrIS cloud fraction - Descending Exclude FORs with poor retrievals Compare with T500 diff in next slide

Slide 15

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

Slide 16

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

Slide 17

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

Slide 18

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

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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 Reference: ECMWF All sky

Slide 20

Angle affects CrIMSS sounding - Ascending Reference: CrIS radiance obs Clear sky Ocean only Lower atmosphere Upper atmosphere Combination of T/ angle dependency T angle dependency Mean difference between CrIS obs and calc An example of CrIS Tb spectrum in longwave CO2 band

Slide 21

Angle affects CrIMSS sounding - Descending Reference: CrIS radiance obs Clear sky Ocean only Lower atmosphere Upper atmosphere Combination of T/ angle dependency T angle dependency An example of CrIS Tb spectrum in longwave CO2 band Mean difference between CrIS obs and calc

Slide 22

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