2002 Annual

Sunday, 13 January 2002
Work-station Eta model forecasts on AWIPS
Alan M. Cope, NOAA/NWS, Mount Holly, NJ
Since March 2000 the National Weather Service Forecast Office at Mount Holly, NJ (PHI) has been running a work-station version of the Eta model, which is based on the operational Eta model run at the NOAA Environmental Modeling Center in Washington, D.C. As of June 2001, forecast fields from the work-station Eta (WS-Eta) are being routinely imported into the AWIPS system at PHI, so that they are readily available to operational forecasters. The WS-Eta model domain is 75 rows by 121 columns, with a horizontal grid spacing of about 7.5 km. This domain covers an area approximately from 36.5N to 44.5N, and 70.0W to 83.0W, or from the VA/NC border to northern NY, and from Cape Cod, MA to central OH.

The WS-Eta at PHI runs four times per day, initialized at T=00Z, 06Z, 12Z and 18Z, producing forecasts every three hours out to 24 hours. A 24 hour forecast takes about 2.5 hours wall clock time on a Dell Precision Workstation 420, with dual 800 MHz Pentium III processors, running the Red Hat Linux 6.2 operating system. The WS-Eta runs must wait for the operational Eta to provide initial and boundary conditions, so runs begin at T+3 hours and end at about T+6 hours, including about 0.5 hours to download grid tiles from the operational Eta.

At this time it is uncertain what benefits, if any, to forecast operations may follow from the availability of WS-Eta forecasts. The 7.5 km grid spacing compares favorably with the operational Eta's grid spacing of about 20 km. This should allow for better resolution of horizontal gradients, e.g., land-sea temperature difference, and possibly better forecasts of related sea-breeze effects. The more detailed WS-Eta model terrain may be significant for the northwest part of the PHI forecast area, where some elevations exceed 600 m. The WS-Eta also provides a choice of two convective parameterization schemes, as well as a non-hydrostatic option. If possible, case studies will be presented to show the effects of these options on WS-Eta forecasts in AWIPS.

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