Evaluation of the NCEP Mesoscale Eta Model Convective Boundary Layer for Air Quality Applications

Abstract

Atmospheric models are a basic tool for understanding the processes that produce poor air quality, for predicting air quality problems, and for evaluating proposed solutions. At the base of many air quality models is a mesoscale meteorological model. The National Centers for Environmental Prediction (NCEP) is now using a model with spatial resolution better than that used for many previous air quality studies. Mixing depth and wind and temperature profiles in the convective boundary layer are the key parameters that must be predicted correctly by a meteorological model for air quality applications. This paper describes an evaluation of the Eta Model predictions of these parameters based on comparisons to measurements made by boundary layer wind profilers at sites in Illinois and Tennessee. The results indicate that the Eta Model is quite usable as a meteorological driver for air quality modeling under reasonably simple terrain and weather conditions. The model estimates of mixing depth, boundary layer winds, and temperature profiles are reasonably accurate. This performance stems from a combination of recent Eta Model advancements in PBL and surface layer physics, land surface physics, 4D data assimilation, and vertical and horizontal resolution.