WRF PreProcessing System (WPS) A Brief Overview. Dr Meral Demirtaş Turkish State Meteorological Service Weather Forecasting Department. WMO, Training Course, 26-30 September 2011 Alanya, Turkey. Outline. What is WPS? Components of the WPS geogrid ungrib metgrid. What is WPS?
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A Brief Overview
Dr Meral Demirtaş
Turkish State Meteorological Service
Weather Forecasting Department
WMO, Training Course, 26-30 September 2011
Coriolis parameters at every grid point
topography height, land use category, soil type, vegetation fraction, monthly surface albedo)
* The real earth is (roughly) an ellipsoid
* But WRF computational domains are defined by rectangles in the plane
4.Latitude-longitude (for global domain, you must
choose this projection!)
(If two are given, the order doesn’t matter.)
* Good for high-latitude domains, especially if domain must contain a pole
* A single true latitude is specified
* Required for global domains
* It may be also used for regional domains
* It can be used in its normal or rotated aspect
In some cases, it may be computationally better to rotate the poles of the projection away from the poles of the earth
* When placing a nest over a
region that would otherwise lie
within a filtered region
* When using the lat-lon
projection for limited area
location in the domain (by default, the center point of the domain)
In general, source data (GFS, NAM, RUC and etc) are given on a different projection from the WRF model grid.
1.Which fields will be produced by geogrid
2.What sources of data will be used
3.How the data will be interpolated/smoothed
4.Any derived fields (e.g., dominant cat., df/dx)
so user will not generally need to edit the file.
interpolate new static fields
(where n is the domain ID #)
(read_met_module.F and write_met_module.F)
* under the “Downloads” tab:
(defined by geogrid)
An ARW grid-cell labelled for mass (θ) and wind (u, v )
U-component = westerly component;
V-component = southerly component
U-component (V-component) parallel to source model x-axis (y-axis)
A wind vector (u,v) with respec to the WRF grid
A wind vector (u,v) with respect to the its source grid
Note that this rotation process may require two successive rotations: one from source grid to earth grid and a second from earth grid to WRF grid.
In ARW, we also get the first time period for all nested grids
met_em.d0n.YYYY-MM-DD_HH:mm:ss.nc (where n is the domain ID #)
Thanks to WPSpresentations of Michael Duda of NCAR/MMM Divisionfor providing excellent starting point for this talk.