18th Conference on Weather and Forecasting, 14th Conference on Numerical Weather Prediction, and Ninth Conference on Mesoscale Processes

Monday, 30 July 2001
An objective evaluation and regime classification of RAMS forecast errors during the 2000 Florida warm season
Jonathan L. Case, NASA Kennedy Space Center/Applied Meteorology Unit/ENSCO Inc., Cocoa Beach, FL; and J. Manobianco, A. V. Dianic, D. E. Harms, and P. N. Rosati
Poster PDF (93.1 kB)
This paper describes a component of the Applied Meteorology Unit’s (AMU) evaluation of the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS is designed to provide emergency response guidance for operations at the Cape Canaveral Air Force Station (CCAFS) and Kennedy Space Center (KSC), Florida, in the event of an accidental hazardous material release or an aborted vehicle launch. The evaluation protocol is based on the needs of Eastern Range safety and weather personnel, and designed to provide specific information about the capabilities, limitations, and daily use of RAMS in ERDAS for operations at KSC/CCAFS. The prognostic data from RAMS is available to ERDAS for display and input to the Hybrid Particle and Concentration Transport (HYPACT) model. Thus, the accuracy and sensitivities of the HYPACT model are contingent upon the prognostic data from RAMS.

In ERDAS, RAMS is run in real-time on four nested grids with horizontal resolutions of 60, 15, 5, and 1.25 km using full microphysics on all grids. The model is initialized twice-daily at 0000 and 1200 UTC using operationally-available observational data and run for a 24-h forecast period on local workstations with multiple processors. The 12-h forecast from the National Centers for Environmental Prediction Eta model provides the background field for the initial condition and the Eta 12-36-h forecasts are used as boundary conditions.

The primary goal of the evaluation is to determine the accuracy of RAMS forecasts during all seasons and under specific weather regimes. The overall evaluation consists of an objective and a subjective component; however, this paper presents the results of the objective component only. The objective evaluation focuses on point error statistics and the sensitivity of the model forecasts to physical parameterizations, resolution, and other factors. A high-resolution network of KSC/CCAFS surface wind towers located entirely within the 1.25-km RAMS grid is used for model validation. The AMU computed error statistics of temperature, wind, and moisture at the KSC/CCAFS wind-tower locations in east-central Florida.

This paper will present wind and temperature error statistics from the KSC/CCAFS tower network classified by three regimes. First, the cumulative statistics for the months of May-September 2000 will be discussed. Second, the point forecast errors will be shown for prevailing surface wind regimes: easterly, westerly, and light or light and variable. Finally, the RAMS forecast errors will be presented for combinations of forecast and observed thunderstorm days. The point error statistics for all these regimes will be presented at the conference.

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