CWB Midterm Review 2011

Forecast Applications BranchNOAA ESRL/GSD

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.

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.

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

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

Analysis increment comparison

No adjust

AdjustedWith no Height check (50m)

AdjustedWith Height check (50m)

AdjustedWith bkgd

Comparison with the current STMAS surface analysis: Better terrain/land-water usage and flow dependent

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.

STMAS analyses

With the LAPS balance Without the LAPS balance

Specific humidity 3h forecasts

With the LAPS balance Without the LAPS balance

Wind speed 3h forecasts

With the LAPS balance Without the LAPS balance

Comparing to the observations, both forecasts are good;

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).

Radar reflectivity impact (6 hr)WRF initialized by LAPSwithout reflectivity

WRF initialized by LAPSwith reflectivity

Cumulative precipitation obs (6h)

Precipitation Forecasts (6 hr)WRF initialized by LAPSwith GFS at boundary

WRF initialized by STMASwith GFS at boundary

Cumulative precipitation obs (6h)Lighter precipitation

Morakot: Reflectivity Analyses

LAPS analysis STMAS analysis

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

Wind forecasts at 6h

LAPS

STMAS

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

Impact by microphysics

STMAS has been tested with a WRF with different microphysics, WSM5 vs. WDM 6

WSM5 WDM6

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.

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.