SCC/NN Retrieval Status and Plans In Support of ROSES - - PowerPoint PPT Presentation

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SCC/NN Retrieval Status and Plans In Support of ROSES - - PowerPoint PPT Presentation

SCC/NN Retrieval Status and Plans In Support of ROSES NNH06ZDA001N-EOS William J. Blackwell and Frederick W. Chen AIRS Science Team Meeting October 11, 2007 This work was sponsored by the National Oceanic and Atmospheric Administration under


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SLIDE 1

AIRS Science Team: 1 WJB 10/23/07

MIT Lincoln Laboratory

SCC/NN Retrieval Status and Plans

In Support of ROSES NNH06ZDA001N-EOS

This work was sponsored by the National Oceanic and Atmospheric Administration under contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the United States Government.

William J. Blackwell and Frederick W. Chen AIRS Science Team Meeting

October 11, 2007

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SLIDE 2

MIT Lincoln Laboratory

AIR Science Team: 2 WJB 10/23/07

Algorithm Improvement Activities

  • Preliminary forecast assimilation results (Prof. Kalnay and

Hong Li) indicate problems with elevated surface terrain and polar regions

– Further data stratification is needed to improve performance in these regions – Preliminary experiments are encouraging – (We think) these are the last remaining issues to be resolved before SCC/NN “Release 1.0”

  • Work is planned to:

– Improve quality and quantity of QC flags – Retrieve spectral surface emissivity – Improve performance over land

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SLIDE 3

MIT Lincoln Laboratory

AIR Science Team: 3 WJB 10/23/07

Planned IASI Activities

  • Adapt Stochastic Cloud Clearing for IASI

– Non-uniform FOV effects may be corrected as part of the SCC algorithm – SCC algorithm uses PC signatures to characterize/correct clouds and can therefore be trained to ignore “corrupted” PC’s

  • Canonical correlation analysis (Projected PC)

– Used as preprocessor for neural network estimation – Allows blending of radiance and temperature/moisture vector subspaces – We can therefore relate PC’s to geophysical quantities, which should help us identify/separate “signal” and “noise”.

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SLIDE 4

MIT Lincoln Laboratory

AIR Science Team: 4 WJB 10/23/07

SCC/NN Release 1.0

  • Fortran modules are in development that will be compatible

with the NASA/NOAA Level 2 software

– Thanks to Chris Barnet and John Blaisdell for help with this

  • SCC/NN retrieval can be “plugged in” to current system to

provide alternate first-guess retrieval and/or cloud-cleared radiances for Version 6 testing

– Subroutines for retrieval initialization and execution – Coefficient data read from binary file (probably HDF)

  • Primary objective: Improve Level 2 retrieval accuracy/yield

in heavily clouded areas

  • Release planned for December 2007
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SLIDE 5

MIT Lincoln Laboratory

AIR Science Team: 5 WJB 10/23/07

Summary

  • Recent validation exercises with independent data indicate

that global SCC/NN temperature and moisture profile retrieval accuracies are very good.

  • This testing has also identified problem areas (elevated

terrain, polar regions) that we are working on.

  • We are shooting for a “Version 1.0” release of coefficients

and code (Matlab and Fortran) at the end of this year.

  • Current algorithm work focused on the QC improvement

(critical for Version 6 testing) and surface retrievals.

  • Related work with IASI is progressing.
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SLIDE 6

MIT Lincoln Laboratory

AIR Science Team: 6 WJB 10/23/07

Backup Slides

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SLIDE 7

MIT Lincoln Laboratory

AIR Science Team: 7 WJB 10/23/07

Algorithm Overview (Part I)

  • Temperature and moisture profile retrievals are produced in all cloud conditions
  • Cloud-cleared radiance estimates are produced for all 2378 AIRS channels
  • Retrieval is global:

– All latitudes – Ocean and land – Day and night

  • Quality control has been implemented
  • IR-only option implemented
  • Very fast: Cloud-cleared radiances and retrieved profiles generated for one field
  • f regard in ~1 msec using PC!!

– Two-three orders of magnitude faster than current operational methods – One-two orders of magnitude faster than iterative, pseudochannel methods

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SLIDE 8

MIT Lincoln Laboratory

AIR Science Team: 8 WJB 10/23/07

Algorithm Overview (Part II)

  • Algorithm is composed of linear and non-linear statistical
  • perators

– Projected principal components transform – Neural network estimation

  • Coefficients are derived empirically, off-line:

– Co-location of sensor measurements with “truth” (Radiosondes, NWP, etc.) – Model-generated data – Data stratification is used for:

Sensor scan angle Latitude Solar zenith angle Surface type Surface elevation

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SLIDE 9

MIT Lincoln Laboratory

AIR Science Team: 9 WJB 10/23/07

Retrieval Performance Validation with AIRS/AMSU

  • >500,000 co-located AIRS/AMSU/ECMWF observations from

seven days:

– 2002: Sep 6 – 2003: Jan 25, Jun 8, Aug 21, Sep 3, Oct 12, Dec 5

  • ~100,000 profiles set aside for validation set
  • ~2000 radiosondes from NOAA FSL global database co-

located with AIRS/AMSU observations

Global: Cloudy, Land & Ocean, Day & Night Case 1: ECMWF atmospheric fields Case 2: Radiosonde data ** NEW **

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SLIDE 10

MIT Lincoln Laboratory

AIR Science Team: 10 WJB 10/23/07

SCC/NN T(h) Retrieval (versus RAOBs) For comparison: AIRS L2 v4

Version 4 Version 4

Land, All latitudes, Radiosondes

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SLIDE 11

MIT Lincoln Laboratory

AIR Science Team: 11 WJB 10/23/07

T(h) RMS Error Versus Cloud Fraction Common Ensemble (Qual_T_Top)

Version 4

Land, All latitudes, Radiosondes

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SLIDE 12

MIT Lincoln Laboratory

AIR Science Team: 12 WJB 10/23/07

SCC/NN W(h) Retrieval (versus RAOBs) For comparison: AIRS L2 v4

Land, All latitudes, Radiosondes

Version 4 Version 4