Effects of mesoscale weather disturbances on contamination concentrations. Fourth technical progress report, August 1, 1976--October 31, 1977

The objective of this research is the development and verification of a regional scale numerical weather prediction model for use in forecasting air pollution concentrations. The scope includes verification of meteorological forecasts of flow fields, boundary layer structure and precipitation using three hourly rawinsonde data in the central and eastern United States. A prototype regional numerical weather forecast system has been developed. This system includes codes to read in the first guess data and the observational data needed to initialize the prediction model. Other codes use these data to perform an isentropic analysis of the wind, temperature and pressure fields and analysis of the humidity field using optimal interpolation. Subsequent codes transform these analyses to the prediction grid and adjust the wind field to remove the vertically integrated mass convergence. The output from that code is the input to the fine mesh prediction model that uses a 140 km grid size and makes a 24 h forecast. Fine mesh model output is used to initialize the mesoscale model and provide time dependent lateral boundary tendencies to the mesoscale model. The mesoscale model is on a 35 km grid and normally makes a 12 h forecast during some portion of the 24 h fine mesh forecast period