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Numerical Forecast Systems


Highlights for HWRF's 2014 implementation include the following:

1. HWRF Infrastructure/Resolution Upgrades : The NMM core of the operational HWRF model will be upgraded to latest community version ref erred to as V3.6a. Due to computational constraints, FY13 HWRF was run with a coarse vertical resolution of 42 levels with model top extending only up to 50 hPa. Proposed FY14 HWRF will have vertical resolution increased to 61 levels with model top extending up to 2 hPa. This will al low the model to have the much desired higher resolution in PBL, and resolve the upper atmosphere more accurately. Extending the model top to 2 hPa will allow the HWRF Data Assimilation System to ingest more satellite radiance data which usually peaks above 50 hPa. The nest domain si zes will be increased by 20% for the 9km domain and by 10% for the 3km domain to allow the high-resolution nests capture larger storm regions w ithin the moving domains.

2. HWRF Physics Upgrades : HWRF physics will undergo major upgrades which include RRTM-G for radiation, modified Ferrier Microphysics w ith advection of individual hydrometeors and an advanced land surface model (NOAH LSM). Radiation upgrades will improve the cloud-radiation in teractions with better representation of cloud top cooling and cloud base warming. The proposed microphysics upgrades will enhance representati on of the storm structure and provide more realistic distribution of hydrometeors, especially ice concentration and fall speeds. For the first time, a 4-level NOAH land surface model will be introduced into HWRF as a replacement of the GFDL slab model. NOAH LSM upgrades will address the cold land surface temperature bias noted in the current HWRF model forecasts, and will also provide the required surface runoff and base fl ow variables for landfall related downstream applications of river routing model and hydrology models.

3. HWRF Initialization Upgrades : Vortex initialization is modified with further improvements to the storm size correction and resizing the filter domain, and will better align the filtered vortex and the environment. For the first time, we will be continuously cycling the vort ex from unnamed depressions (invests) when they transition into numbered/named storms, eliminating the cold starts for tropical storms.

4. HWRF Data Assimilation System (HDAS) Upgrades : The 80-member global ensembles based one-way hybrid EnKF-3DVAR data assimilation sys tem for HWRF will further be upgraded to include more satellite data sets and aircraft recon data sets along with the NOAA-P3 Tail Doppler Rada r data. The GSI system will be further tuned to improve the initial analysis for all HWRF domains.

5. HWRF Ocean Upgrades : Ocean model component of HWRF will be upgraded to multi-processor MPI-POM-TC with single trans-Atlantic domain and for the first time, a 3D ocean for Eastern Pacific basin instead of the current 1-D POM. The ocean model resolution will increase from 1/ 6o to 1/12o and will have a modified feature based initialization suitable for the MPI POM-TC model.

6. HWRF Coupler Upgrade : The single processor NCEP coupler in HWRF model will be upgraded to run on multiple processors to enable fast er communications between the atmosphere and ocean components. This is required due to increased resolution

7. HWRF Post-Processing and Product Upgrades : HWRF post processing upgrades will include additional simulated synthetic imagery from d ifferent satellite sensors, and will have new products requested by SPC (tornadic potential fields) and for downstream applications including H urricane Wave Model. For the first time, FY14 operational HWRF will now have complete GRIB2 support, eliminating all GRIB1 products from opera tional suite.

8. HWRF Script Enhancements and Procedural Upgrades : Operational HWRF scripts will undergo major enhancements with better exception ha ndling features and efficiency. The new python based scripts will eliminate lot of duplication and will greatly reduce the length of HWRF scri pts in operations. They also provide for the first time the opportunity to unify various versions of the scripts used by the community and dev elopers. They also have the flexibility to add features that can be utilized for graphics and automation. Operational HWRF will remain in the v ertical structure and will be known as hwrf.v8.0.0 on WCOSS.