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
Slide 19
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