Validation of crimss sounding products of 20120515
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Validation of CrIMSS sounding products of 20120515 PowerPoint PPT Presentation


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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

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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


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