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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 - PowerPoint PPT Presentation
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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
• Computed using high-frequency model output. Files processed using short fortran program that writes netcdf tendency file.
• Plotted via NCL
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
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
Inner-Core Verification
• 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
Wind Speed
Prior Analysis Obs.
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 NCLMetrics: circulation, thickness, humidity, vertical shear, divergence, precipitation, average winds
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
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
Environment ShearRemove effect of storm from estimate of vertical shear between two levels (subscripts 1 and 2) by removing vertical difference of storm-related vorticity () and divergence ()
2 1 022 1 2 1
0
for( ) ; 0 on lateral boundaries
0
r r
r r
2 1 022 1 2 1
0
for( ) ; 0 on lateral boundaries
0
r r
r r
2 1 2 1ˆ ( ); ( )v k v
2 1envv v v v v
200 mb – 900 mb wind difference (and 900 mb relative vorticity): EPAC developing composite
Due to storm
200 mb – 900 mb wind difference with storm removed:EPAC developing composite
Davis et al., 2008: MWR
HWRF Histograms
• Convert ATCF to netcdf
• Histogram constructed via Matlab
• Plotting either via Matlab or NCL
HWRF Histograms
• Convert ATCF to netcdf
• Histogram constructed via Matlab
• Plotting either via Matlab or NCL
Future Diagnostics
• H*WIND comparisons (either RMS difference or quadrant-by-quadrant fraction coverage, similar to Marchok calculation)
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