Difference between revisions of "WRF Hindcast"
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Revision as of 17:33, 4 March 2017
The WRF Hindcast Project generates the data used in the Grow Degree Calculator and the Soil Moisture Estimator projects. WRF stands for Weather, Research, and Forecasting and is a program made available by UCAR/NCAR and other research participants.
WRF is normally used to forecast weather, but for our purposes we use it to simulate weather in the past.
Contents
Sectors
The area modeled by the WRF program is called a "domain", but since this implementation uses three domains (at 30km, 10km, and 3.3km resolution), the area of interest, the third domain, is called a "sector". Each sector is made up of 171x171 "pixels", 3.3km x 3.3km in size. Client programs can access the pixel's data by indicating latitude and longitude coordinates.
The image to the right depicts sectors defined, and those currently active (operational) are shown in green. This set of sectors are designated WCONUS (Western Continental United States) with an appellation of grid location. Sector rows are given letters and columns are given numbers, with the origin on the bottom right. For example, the bottom right sector is WCONUS_A0 and the top left sector is WCONUS_E4. Grid coordinates are based on data delivery needs and computation capacity. The most eastern sector users will want data earlier than the western ones, by about two hours, and so computation starts with "0" column. Likewise, the most southern sectors will have an earlier planting season than northern ones, and so the most southern row is "A".
Procedure
Input Files
GFS
Our implementation of the WRF program uses the Global Forecast System (GFS) as input forcing files. These are files generated by NOAA (NCEP) which are used to force data interpolations to defined values at certain times, projected into the future at six hour intervals. Once those projected times are reached, the forcing file is regenerated using real data instead of projected data and a new set of projected files are then generated, etc. This project uses the re-analyzed files at six-hour intervals for historical evaluation.
WRF Output
Domain sizes 171x171 variables
