CWB M idterm Review 2011
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Transcript of CWB M idterm Review 2011
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CWB Midterm Review 2011
Forecast Applications BranchNOAA ESRL/GSD
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New STMAS surface analysis software
• A new version of STMAS surface analysis system is installed in CWB in May, 2011;
• It is multivariate, flow-, terrain, land-water dependent;
• It processes CWB observation datasets considering terrain differences between obs stations and analysis grid height;
• Constraints will be added in the next upgrade.
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Surface Observation Quality Control
• Standard deviation QC check is added;• When temperature, dew-point and station
pressure observations are available, the pressure is reduced to the analysis grid height;
• When temperature and dew-point obs are not available, an option of using model background for pressure adjustment;
• STMAS new 3D/4D will solve this issue.
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Standard Deviation from the background
Raw CWB station pressure obsStandard deviation from bkgd
After applied the pressure Adjustment, the standardDeviation from background
These stations do not have either temperature or dewpoint obs
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Options
For terrain difference is too large (50m?), QC these pressure data (removed, see figure);
Use background temperature and dewpoint to adjust the station pressure
Background adjustment helps reduce the deviation but is not as good the observation adjustment
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Analysis increment comparison
No adjust
AdjustedWith no Height check (50m)
AdjustedWith Height check (50m)
AdjustedWith bkgd
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Comparison with the current STMAS surface analysis: Better terrain/land-water usage and flow dependent
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Specific Humidity Issue• STMAS 3D uses LAPS cloud, hotstart and balance packages
temporarily;• STMAS full 3D-4D variational cloud, hotstart and balance are under
development;• Issues on specific humidity appear, showing zero SH at 950, or low
heights;• Thorough debugging and testing show that the problems come from
the LAPS humidity and balance packages.• Temporary solutions are recommended for CWB and two independent
analysis and forecast domains are set up at GSD for comparison, one with LAPS balance and the other without LAPS balance;
• Both CWB and GSD runs show slightly better forecasts without using LAPS balance package.
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STMAS analyses
With the LAPS balance Without the LAPS balance
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Specific humidity 3h forecasts
With the LAPS balance Without the LAPS balance
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Wind speed 3h forecasts
With the LAPS balance Without the LAPS balance
Comparing to the observations, both forecasts are good;
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STMAS Reflectivity Analysis: Morakot
• A reflectivity analysis operator has been implemented for STMAS 3-4D analysis;
• STMAS 3-4D is applied to Morakot Typhoon case again for evaluating precipitation forecasts;
• It is found that a better wind forecast from STMAS helps its precipitation forecast comparing to LAPS WRF forecast (identical setup but only analyses are from STMAS or LAPS).
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Radar reflectivity impact (6 hr)WRF initialized by LAPSwithout reflectivity
WRF initialized by LAPSwith reflectivity
Cumulative precipitation obs (6h)
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Precipitation Forecasts (6 hr)WRF initialized by LAPSwith GFS at boundary
WRF initialized by STMASwith GFS at boundary
Cumulative precipitation obs (6h)Lighter precipitation
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Morakot: Reflectivity Analyses
LAPS analysis STMAS analysis
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Wind forecasts at 1h
LAPS
STMAS
• The reflectivity analyses ofLAPS and STMAS are quitesimilar;
• Wind forecasts from bothanalyses are examined;
• The one hour wind forecastsshow relatively good typhoonstructures, both from LAPS and STMAS
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Wind forecasts at 6h
LAPS
STMAS
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Impact by STMAS multigrid levels
STMAS has been tested with different numbers of multigrid levels,
2 multigrid levels vs. 3 levels
STMAS with 2 multigrid levels STMAS with 3 multigrid levels
Differenceof theseanalyses
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Impact by microphysics
STMAS has been tested with a WRF with different microphysics, WSM5 vs. WDM 6
WSM5 WDM6
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Preliminary conclusions
• The radar reflectivity improves precipitation forecasts;• The wind analysis is quite important for precipitation
forecasts;• Multigrid improves the forecasts;• Different microphysics schemes affect the forecast in
detailed precipitation but not as much as the wind analysis;• Different boundary conditions has some impacts as well.
All are preliminary and further study will be needed in term of analysis schemes, microphysics and boundary conditions.
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Outlook for the remaining tasks
• Hotstart is under development (working with CWB and resolve issues with the LAPS hotstart and balance issues);
• Cycling issues are being investigated and the lateral boundary plays an important role (working with CWB on fixing a boundary consistency issue);
• Downscaling: more case studies have been done and looking for potential typhoon cases for CWB.
• Satellite data assimilation: Test of CRTM for AMSU-A data for STMAS variational analysis using CRTM K-matrix.