Impact of ensemble mesoscale meteorological data used as input

The Utah Division of Air Quality, the National Center for Atmospheric Research, and the Dugway Proving Ground (DPG) Meteorology Division are collaborating on a study linking high-resolution ensemble weather model output data with an air quality model. The goal of the study is to evaluate the potential utility of this approach in developing Utah's State Implementation Plan (SIP). Traditionally, the impacts of emission-control strategies for SIPs are evaluated based on a single meteorology-chemistry model run. This approach ignores the possible uncertainty associated with any single model run and casts doubt on the efficacy of a chosen emissions control strategy. Ensemble weather modeling is a tool that allows for the quantification of prediction variability. This variability can be used to demonstrate the uncertainty of the impact of selected emission control strategies. The ensemble weather model used in this study is the 30-member operational mesoscale system, using Weather Research and Forecasting (WRF) and Mesoscale Meteorological Model, Version 5 (MM5) coupled with the Real-Time Four-Dimensional Data Assimilation (RT-FDDA) system used in the Army Test and Evaluation Command (ATEC) Four-Dimensional Weather (4DWX) system. Output from the 4DWX system is used to drive the Community Multiscale Air Quality (CMAQ) three-dimensional atmospheric chemistry and transport model. RT-FDDA and 4DWX were developed by National Center for Atmospheric Research (NCAR) for the U.S. Army Test and Evaluation Command (ATEC) Operational Meteorology Program. The Ensemble-4DWX system is operated by the DPG Meteorology Division using a computer cluster provided by the Department of Defense (DoD) High-Performance Computing Modernization Program.