Application and Evaluation of Satellite Vegetation and Albedo in the MPAS-CMAQ Global Modeling System

We have enhanced the Model for Prediction Across Scales – Atmosphere (MPAS-A) for the next generation of air quality model development with the Community Multiscale Air Quality (CMAQ) modeling system. The enhanced version of MPAS-A includes the addition of four-dimensional data assimilation, the Pleim-Xiu land surface model (PX LSM), and Asymmetric Convective Model 2 planetary boundary layer model. 2011 National Land Cover Database (NLCD) and Moderate Resolution Imaging Spectroradiometer (MODIS) land cover data sets are used for land surface representation in the PX LSM. Here we present the evaluation of MPAS-A surface representation and simulated meteorology with land surface updates using satellite vegetation and albedo products.

Accurate description of surface characteristics is important in meteorology and air quality modeling systems, particularly in global simulations using MPAS-CMAQ, for the exchange of heat, moisture, momentum, and trace atmospheric chemicals between the land surface and the atmosphere. In the MPAS-CMAQ, surface characteristics including vegetation parameters and surface albedo are specified in the LSM look-up tables by NLCD-MODIS land use categories. Plant phenological dynamics are modeled using simple time- and temperature-dependent functions. The goal of this research is to improve land surface modeling in MPAS-CMAQ by incorporating satellite temporal vegetation and albedo products for faithful surface representation. Albedo and leaf area index (LAI) are two important parameters in meteorology and air quality modeling because albedo affects not only the surface energy budget and fluxes, but also photolysis rates in the air quality model. LAI is important not only for scaling leaf level fluxes to the canopy level, but also for controlling deposition of various atmospheric gases and particles. We will evaluate the LAI and albedo from the current MPAS-CMAQ configuration against observation data from satellite products and ground measurements. This presentation will focus on MPAS-A global meteorology simulations of 2016. Simulated meteorology (e.g. temperature, moisture, wind speed and direction) will be compared and evaluated among different simulations with table-prescribed LAI and albedo and with satellite LAI and albedo. The benefits and issues in using satellite LAI and albedo products will be demonstrated with analysis against measurement data.