Atmospheric Boundary Layer Modeling for Combined Meteorology and Air Quality Systems

Atmospheric Eulerian grid models for mesoscale and larger applications require sub-grid models for turbulent vertical exchange processes, particularly within the Planetary Boundary Layer (PBL). In combined meteorology and air quality modeling systems consistent PBL modeling of winds, temperature, humidity, and chemical concentrations is necessary for accurate simulation of chemical transport through the 3-d grid and accurate simulation of gas-phase and aerosol chemistry. A recently developed PBL model, known as the Asymmetric Convective Model version 2 (ACM2), has been designed to represent realistic turbulent transport of atmospheric constituents. The ACM2 has local and non-local components for transport in convective boundary layers. Evaluation of the ACM2 involves comparisons to observed vertical profiles of meteorology and chemistry. For example, simulations of the Weather Research and Forecast (WRF) model and the Community Multiscale Air Quality (CMAQ) model are compared to vertical profiles of potential temperature, water vapor mixing ratio, and several trace chemical species from aircraft and balloon soundings. The modeled vertical structures of chemical and meteorological parameters are consistent with observations