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Advanced AHW Diagnostics

Advanced AHW Diagnostics. Ryan D. Torn, Univ. Albany SUNY Chris Davis, NCAR. AHW Assimilation System Diagnostics AHW Forecast Diagnostics Ready-to-go HWRF Diagnostics. Pressure Tendency. Measure of the imbalance in initial conditions

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Advanced AHW Diagnostics

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  1. Advanced AHW Diagnostics Ryan D. Torn, Univ. Albany SUNY Chris Davis, NCAR • AHW Assimilation System Diagnostics • AHW Forecast Diagnostics • Ready-to-go HWRF Diagnostics

  2. Pressure Tendency • Measure of the imbalance in initial conditions • Computed using high-frequency model output. Files processed using short fortran program that writes netcdf tendency file. • Plotted via NCL

  3. Observation Verification • Large-scale model errors and biases • Windowing by region can demonstrate more detailed model bias information • Computed within AHW assimilation system, could extend to HWRF if grids are made available • NCL or Matlab plotting

  4. Near-TC Verification • Compute errors relative to obs. near TC. Primarily for diagnosing near-storm environmental errors • Done from fortran program that windows observations based on distance to TC • Aggregation using fortran program

  5. Inner-Core Verification Wind Speed • Comparison against aircraft and dropsonde obs. in vortex-relative space. Eliminates position-related errors. • Computed via fortran program that reads WRF files and obs. from DA system and writes model estimates at observation locations. • Plotting with Matlab, with transition to NCL Temperature PriorAnalysis Obs.

  6. Lagrangian Diagnostics • Used extensively during PREDICT to evaluate processes that lead to genesis • Each Lagrangian metric is computed using a separate fortran program, could be merged into single application • Plotting via NCL Metrics: circulation, thickness, humidity, vertical shear, divergence, precipitation, average winds

  7. Histogram Verification • Shows conditional biases • In assimilation system, computed via separate fortran program, aggregated via Matlab script, output as netcdf • AHW forecasts have all-in-one fortran program • Calculations can include equitable threat scores • Plotting accomplished via Matlab with transition to NCL Davis et al. 2010, WAF

  8. Climatology Comparisons • Shows whether the model can replicate the observed distribution of a quantity, shows systematic biases • Easy to compute once you have quantities Davis et al. 2010, WAF

  9. Environment Shear Remove effect of storm from estimate of vertical shear between two levels (subscripts 1 and 2) by removing vertical difference of storm-related vorticity (z) and divergence (d) Due to storm 200 mb – 900 mb wind difference with storm removed: EPAC developing composite 200 mb – 900 mb wind difference (and 900 mb relative vorticity): EPAC developing composite Davis et al., 2008: MWR

  10. HWRF Histograms • Convert ATCF to netcdf • Histogram constructed via Matlab • Plotting either via Matlab or NCL

  11. HWRF Histograms • Convert ATCF to netcdf • Histogram constructed via Matlab • Plotting either via Matlab or NCL

  12. Future Diagnostics • H*WIND comparisons (either RMS difference or quadrant-by-quadrant fraction coverage, similar to Marchok calculation)

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