Initial validation of an ambient air quality model for Naval air operations

Abstract

A previously developed model was updated to appropriately represent 1978/79 operations and then evaluated for prediction sensitivity to variations in meteorological and dispersion model parameters. A joint effort with the Naval Air Propulsion Center, the Environmental Protection Agency/Northrup Services, Inc. and PMTC, Pt. Mugu was conducted to obtain detailed data over a one-week period. Much of the measured pollution concentration data (including all of the suspended particulate data) was lost due to instrument and measurement technique problems. This severely limited the validation effort. Comparison of model predictions with the limited initial measured concentration data indicated that: (1) predicted CO concentrations were in good agreement with measurement, (2) predicted NOX concentrations from aircraft idle/taxi operations were too low, and (3) predicted total hydrocarbons and particulate concentrations were too high for aircraft idle/taxi operations and too low for environ sources. Model predictions were significantly improved by increasing engine RPM settings to above idle for all modes normally specified as idle. Model validation efforts would be improved if one-half integer stability categories could be measured and used in the model. (Author)