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CIRA AMSU Tropical Cyclone Algorithm

CIRA AMSU Tropical Cyclone Algorithm. 1. Retrieve T(x,y,z) from all AMSU-A channels 2. Correct T for rain and ice effects 3. Hydrostatic integration for P (x,y,z) 4. Gradient wind for V(r,z) 5. Statistical Prediction Independent Variables : Parameters from retrieved T, P, V

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CIRA AMSU Tropical Cyclone Algorithm

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  1. CIRA AMSU Tropical Cyclone Algorithm • 1. Retrieve T(x,y,z) from all • AMSU-A channels • 2. Correct T for rain and ice effects • 3. Hydrostatic integration for P(x,y,z) • 4. Gradient wind for V(r,z) • 5. Statistical Prediction • Independent Variables: • Parameters from retrieved T, P, V • Dependent Variables: • Max Wind (Vmax) • Min Sea-Level Pressure (MSLP) • Azimuthally averaged radii • of 34, 50, 64 kt winds (r34, r50, r64) • 6. Fit parametric wind model to r34, r50, r64 • and storm speed to get asymmetric radii (R34, R50, R64) V(r,Q) Sample r/z tangential wind cross-section from AMSU retrieval (steps 1-4)

  2. 2002 Real-Time Test • Algorithm developed from 1999-2001 Sample • 2002 Real-Time Runs • Initiated at 00, 06, 12, 18 UTC • Storm positions from ATCF • Analysis restricted to storms within 700 km of AMSU data swath • Results sent to TPC via ftp • Evaluation Samples • 1999-2001 Developmental cases (N=473) • 2002 All Atlantic/East Pacific cases (N=288) • 2002 Atlantic/East Pacific cases with recon (N=64) • Ground “Truth” for Evaluation • NHC Best Track Vmax and MSLP • NHC Forecast/Advisory for wind radii

  3. Predicted vs. “Observed” Scatter Plots for 2002 Real-Time Runs (Total and Recon-Only Samples) Vmax MSLP R34 R50 R64

  4. Error Summary for CIRA Algorithm:Developmental, 2002 All and 2002 Recon Samples Absolute Error Variance Explained Vmax MSLP Vmax MSLP Vmax and MSLP R34 R50 R64 R34 R50 R64 R34 R50 R64

  5. Conclusions from 2002 Evaluation • Vmax, MSLP: • 2002 errors very similar to dependent sample • Intensity still underestimated for strongest storms • Test dependent variable transformation for improvement • Wind Radii: • 2002 recon-only errors generally similar to dependent sample • Tendency for high bias for R50 and R64 • Observed R50 and R64 more asymmetric than predicted • Test variable asymmetry factor (different for R34, 50 and 64) • Suggestion to JHT: • Re-develop algorithm with 2002 cases added • Nearly doubles dependent dataset • Test suggested improvements • Evaluate again following 2003 season

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