Characterization and Validation of Cloud-Cleared Radiances E.F. - - PowerPoint PPT Presentation

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Characterization and Validation of Cloud-Cleared Radiances E.F. - - PowerPoint PPT Presentation

Mar 30, 2023 284 likes •499 views

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California Atmospheric Infrared Sounder Characterization and Validation of Cloud-Cleared Radiances E.F. Fishbein National

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Characterization and Validation

  • f

Cloud-Cleared Radiances

E.F. Fishbein

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Outline

  • ECMF – AIRS inter-comparisons

– Dependence on cloud discriminants – SST outlier rates (2K threshold)

  • Radiance Covariance

– Clear – versus cloud-cleared

  • Inter-comparison of versions 4.0 and 3.5

Name Name Description Location Time of Day Default Condition

d2392r1 d2392r1

Difference of SST from LW and SW channels, SST1231r5- SST2392r1 Ocean Day/Night

> -2K d23 d23

LW Thin cirrus and silicate dust predictor Ocean Day/Night

abs < 0.25K

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 3.5 SST Inter-comparisons Outlier Rate

LW Thin Cirrus Test 1231 / 943 cm-1

  • Discriminant smaller than

clear threshold (density of discriminant)

  • Density of SST differences are

independent of discriminant

  • Precision (bias) and accuracy
  • f SST independent of

discriminant

Cloud-clearing is working to reliability of discriminant and/or Correlative SST

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 3.5

Clear versus Cloud-Cleared Covariance

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 3.5 Conclusions

  • Application of cloud-contamination test

– Most of CC radiances past test

  • Assessment of quality based on impact on retrieved products

– Outlier rate not dependent on clear test

  • Suggests outliers do not arise from errors in CC radiances
  • Statistical Characteristics

– Small differences in most significant eigenvectors

  • Larger more varied ensemble of states
  • Cloud clearing has only 6 degrees of freedom per AMSU footprint

– Correlated errors in cloud formations could amplify variance – AMSU systematic errors could produce correlated errors in cloud formations

– Larger eigenvalues at least significant eigenvalues

  • Evidence for noise amplification
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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 4.0 SST Inter-comparisons Outlier Rate

  • Possibly more skill
  • Outlier rate

decreasing with tightening

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 4.0 SST Inter-comparisons Outlier Rate

LW / SW SST Difference

  • Same as Version 3.4
  • Discriminant smaller than

clear threshold

  • Density of SST differences

independent of discr.

  • Precision (bias) and

accuracy of SST are independent of discr. – Decreases with discr – Outlier rate increases

  • Cloud-clearing is working to

reliability of discriminant

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 4.0

Clear versus Cloud-Cleared Eigenvalues

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Version 4.0

Clear versus Cloud-Cleared Covariance

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Noise Amplification

  • Increase in radiance noise

by cloud clearing

  • Applicable to surface

sensing channels

  • 9 clear footprints has NaF
  • f 1/3
  • Concern about

amplification of systematic errors

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Covariance Dependence on Noise Amplification

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Weighting Function Through Cloud Layers

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Height –Dependence of Noise Amplification

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Latitude Sampling

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Conclusions

  • Application of cloud-contamination test

– Most of CC radiances past test

  • Assessment of quality based on impact on retrieved products

– Outlier rate not dependent on clear test

  • Suggests outliers do not arise from errors in CC radiances
  • Statistical Characteristics

– Small differences in most significant eigenvectors

  • Larger more varied sample of states

– Larger eigenvalues at least significant

  • Evidence of noise amplification
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805 cm-1 Bias

(Window Channel with Strong Water Continuum)

CC = cloud cleared UC = uniform clear

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Clear Scene Prescription

Name Name Description Location Time of Day Default Condition

SST1231r5 SST1231r5

SST from LW channels using a split window Ocean Day/Night

SST2392r1 SST2392r1

SST from SW channels using lapse rate extrapolation Ocen Day/Night

d2392r1 d2392r1

Difference of SST from LW and SW channels, SST1231r5- SST2392r1 Ocean Day/Night > -2K

dd12g5 dd12g5

SST LW/SW difference with glint correction Ocean Day abs < 0.5K

d12 d12

SST LW/SW difference w/o glint correction Ocean Night abs < 0.25K

d23 d23

LW Thin cirrus and silicate dust predictor Ocean Day/Night abs < 0.25K

d34 d34

LW Thin cirrus predictor Ocean Day/Night abs < 0.5K

lrt lrt

SW lapse rate Tropical Ocean Day/Night > 3.5K

g5n g5n

SW sun glint detector Ocean Day < 3

spatial_coh spatial_coh 11 11 um um

Std Deviation in LW predicted SST Everywhere Day/Night < 0.5

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Supplemental Slides

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National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California

Atmospheric Infrared Sounder

Empirical Orthogonal Functions Data

  • Train on 826,340 identified clear spectra (11 Focus

Days)

  • LW temperature sounding channels (470)