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SENSITIVITY OF REGIONAL OXIDANT MODEL PREDICTIONS TO PROGNOSTIC AND DIAGNOSTIC METEOROLOGICAL FIELDS
Citation:
Alapaty, K., D. Olerud, K. Schere, AND A. Hanna. SENSITIVITY OF REGIONAL OXIDANT MODEL PREDICTIONS TO PROGNOSTIC AND DIAGNOSTIC METEOROLOGICAL FIELDS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/529.
Description:
Objective analysis and diagnostic methods are used to provide hourly meteorological fields to many air quality simulation models. he viability of using prognostic predictions from the Mesoscale Model Version 4 together with four-dimensional data assimilation techniques (MM4-FDDA) to provide meteorological information to the. .S. EPA Regional Oxidant Model (ROM) is studied. wo numerical simulations are performed for eight days using the ROM for a domain covering the eastern United States. n the first case, diagnostically analyzed data are used to provide meteorological conditions, while in the second case the MM4's prognostic data are used. omparisons of processed diagnostic and prognostic meteorological data indicate differences in dynamical, thermodynamical, and other derived variables. ncertainties and forecast errors present in the prognostic data led to estimation of lower mixed layer heights and a smaller diurnal range of atmospheric temperatures compared to those obtained from the diagnostic data. omparison of horizontal winds indicated minor differences. hese differences systematically affected the estimation of other derived meteorological parameters, such as friction velocity and sensible heat flux. rocessed emission data also showed some differences that resulted from the differing characteristics of the diagnostic and prognostic meteorological data. omparison of predicted concentrations of primary (emitted) chemical species such as NOx and ROG in the two numerical simulations indicated higher values when the prognostic meteorological data are used. his result is consistent with the lower estimated values of the ROM's layer 1 and layer 2 heights (planetary boundary layer) with the prognostic meteorology. owever, comparison of predicted ozone concentrations did not indicate similar features. redicted concentrations of ozone indicated both increases and decreases over those predicted by the ROM utilizing diagnostic meteorological data. hese results indicate that the prediction of trace gas concentrations and the nonlinearity in the model's chemistry are sensitive to the type of meteorological input used.