EDR Algorithms for the Crosstrack Infrared Sounder Xu

EDR Algorithms for the Cross-track Infrared Sounder Xu Liu Atmospheric Environmental research, Inc. 131 Hartwell. Ave, Lexington, Ma 02421 Contact: Xliu@aer. com and Ronald J. Glumb, Christopher E. Lietzke and Joseph P. Predina ITT Industries, ITT Aerospace/Communications, 1919 West Cook Road, P. O. Box 3700, Fort Wayne, IN 46801, USA Contact: joe. predina@itt. com Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS EDR Products Climateology (first guess) s (NWP) p Surface Map Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 2 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS AMSU/MHS Channels Used (ATMS to replace AMSU/MHS) 3 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IS Channels Used • Channels Excluded During MW/IR Retrieval – Ozone Band from 950 cm-1 to 1095 cm-1 – Trace gas channels – Low information content channels (channel selection) – Good results using only 400, 300 and 150 channels • Special High Information Content Channels Used – 709. 5 cm-1 to 746 cm-1 for cloud parameter h estimation and Principle Component Analysis (PCA) for estimating number of cloud formations – 2190 cm-1 to 2250 cm-1 for cloud parameter h estimation Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 4 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Fast Forward Model • Optimal Spectral Sampling (OSS) Benchmarked against AIRS fast forward model in 1999……… OSS > 20 times faster OSS > 40 times faster when including Jacobians – – – Developed at Atmospheric Environmental Research (AER) Fast and accurate (validated against Line-by-line models) Can model non-localized Instrument Line Shape (ILS) Computes Jacobian efficiently Accurate treatment of reflective radiation from surface Both MW and IR versions developed Only 20% Speed Penalty when Modeling sinc vs. Blackman-Harris Instrument ILS Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 5 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Retrieval Methodology (Rogers, 1976) Error Covariance Matrix of Background Observed Radiance Error Covariance Matrix of Measurement Calculated Radiance General Form Used Matrix of Partial Derivatives of yi With Respect to x Retrieved Variable Background Temp/moisture/ Emissivity/ Reflectivity/ etc. EOF Form Used EOF Form Has Much Smaller Dimension & Is Modified to Handle Nonlinear Case Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 6 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS Retrieved Parameters 7 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (1 of 6) • Initialization Used for First Guess Fast Forward Model Parameters Indexed Every 10 Degree of Temperature Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS – Load instrument specifications (AMSU, MHS, Cr. IS frequencies, Noise, etc. ) – Load climatoligical atmospheric data base – Load surface background data base (Mean profiles, error covariance matrices) – Load OSS parameters (Optical depth tables) – Load solar spectrum – Load topography & land/ocean mask GTOPO 30 Digital Elevation Map, land/ocean mask 8 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (2 of 6) • Preprocessing Interpolated in Time and Space Land/ocean maps & MW Brightness Temperature tests @ 31, 50, 89 & 23 GHz – Test for precipitation – Compute surface pressure from NWP data – Test for surface type • Land • Ocean • Ice • Snow • Coast: ocean/land • Coast: ice/snow – Choose Background by Surface type & mix with emissivity information MW Ocean Emissivity per Wilheit model (Wilheit, 1979) Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 9 MW Land Emissivity per Grody model (Grody, 1988) Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (3 of 6) • Microwave Only Retrieval – Average radiances from 9 MHS FOVs – Execute OSS fast forward model based upon climatology first guess – Perform inversion & update first guess profile – Calculate new radiances using OSS – Test for convergence – Continue iteration if convergence criteria not met Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 10 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (4 of 6) • Scene Classification – Purpose • Maximize # of good retrievals within a field of regard (FOR) • Optimize an FOV clustering strategy for treatment of clouds and use of cloud clearing algorithm – Method • Form matrix of 9 FOVs by 62 IR channels in the spectral region from 709 to 748 cm-1 • Analyze for up to 9 principle components • Determine number of cloud formations present from PCA analysis & 2 statistical tests • Cluster minimum number of FOVs needed to perform cloud clearing Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 3 2 1 6 5 4 9 8 7 Example of PCA Analysis 3 principle components indicating 2 cloud formations 11 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (5 of 6) • Combined MW/IR Retrieval – Uses MW retrieval as first guess (profiles, surface, cloud parameters) – Modified Maximum Likelihood Method for nonlinear retrieval – Dynamically adjust channel weights to improve convergence and stability – Cloud clearing parameter h estimated each iteration – FOVs averaged above 80 mbar – Test for convergence – Continue iterations if convergence criteria not met Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 12 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Retrieval Process (6 of 6) • Quality Control – If normalized c 2 > 1. 0 for the retrieval, then retrieval is not reported – If MW radiances after MW/IR retrieval differ by more than 3 K from observed radiances, then entire retrieval rejected – If MW retrieval and MW/IR retrieval differ by more than 3 K, then the MW/IR retrieval is rejected – If difference between cloud cleared Cr. IMSS radiances and VIIRS cloud free radiance is greater than 2 k, then retrieval is suspect Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 13 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS Performance for Various Levels of Channel Selection 14 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Cr. IS EDR Algorithm Cr. IMSS Projected Performance Based on Global Average Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 15 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.

Expected Improvement Over HIRS Cr. IS EDR Algorithm (RMS Uncertainty, Global Average Basis) Cr. IS HIRS Cr. IS • ITT INDUSTRIES • AER • BOMEM • BALL • DRS 16 Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.