HWRF Idealized Overview

Description of HWRF Idealized

The Hurricane Weather Research and Forecast system (HWRF) Idealized capability is distributed with version 3.8a.

The HWRF model has two classes of initialization: a) ideal vortex and b) real data. For more information on how to build and run HWRF, please refer to the Users Guide.

Starting V3.8a the HWRF Idealized capability include a landfall option. Currently only GFDL Slab land surface physics option is supported for landfall capability and efforts are underway to include other land-surface physics options. A namelist file for land surface configuration introduces a switch for landfalling capability, specifies the type of land surface, initial land-surface temperature to be used over land. The default configuration introduces a homogeneous land surface but can be modified to account for heterogeneity through the source code. The direction of land motion can also be chosen. Two options are available – West to East or East to West.

The idealized simulation requires 00-h and 120-h GFS GRIB2 forecasts, along with a sounding, specifications of the initial vortex, and a namelist. The idealized simulation is performed on the operational triple nested domain configuration, with grid spacings of 18-, 6- and 2-km. All the operational atmospheric physics, as well as the supported experimental physics options in HWRF, can be utilized in the idealized framework. The post processing can be done using the Unified Post-Processor.

A few examples of a run performed with the default configuration are provided here as a benchmark. This run was conducted on the NOAA Jet supercomputer, and users should not expect to obtain identical results when using different computational platforms.

Figure 1 shows 10-m zonal wind (m/s) on the parent domain for the 12-h forecast lead time. Streaks or spotty behavior near the edges occur because the waves cannot propagate beyond the boundary and get refelected back to the domain. Spurious gravity waves do not appear in the innermost domain. Figures 2 and 3 show the meridional wind speed as a cross section and a 850-hPa plan view, respectively. Due to the reflection of waves on the boundary of the parent domain, it is recommended to limit the simulation length to 48 h. Figure 4 shows hi-frequency (5 sec) 12-h intensity and MSLP forecast from the Idealized run. The values are plotted every 5 minutes.

Fig 1                       Fig 2                       Fig 3                      Fig 4

Click for larger image.

Always look for Known Issues before setting up any experiment

For the convience of the user community, sample GFS GRIB2 files for running the idealized case are provided.

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