Meteorological Modeling Using WRF-ARW for Grand Bay Intensive Summer 2010 and Spring 2011

NOAA's Air Resources Laboratory operates a station for the long-term monitoring of atmospheric mercury and other trace species at the Grand Bay National Estuarine Research Reserve (NERR) in Moss Point, MS. The station is one of the first such sites established by the National Atmospheric Deposition Program's Atmospheric Mercury Network (AMNet). Measurements at the site support a range of research activities aimed at improving understanding of the atmospheric fate and transport of mercury. Routine monitoring was enhanced by two intensive measurement periods conducted at the site in summer 2010 and spring 2011. Detailed meteorological data is required to properly represent the weather conditions, determine the transport and dispersion of plumes, and the wet and dry deposition of mercury. To describe the mesoscale features required for the plume calculations for mercury episodes during the Grand Bay Intensive campaigns, finer resolution meteorological simulations were conducted using the Weather Research and Forecasting (WRF) model. The initial and boundary conditions for WRF originated from two set of analyses produced by the National Centers for Environmental Prediction (NCEP) – North American Regional Reanalysis (NARR) which is 3 hourly in 32-km resolution with 45 vertical layers, and global tropospheric analyses available in every 6 hours in 1 x 1 degree spacing and 27 vertical layers. Both reanalysis data went through the objective analysis process to provide improved input for initializing the WRF model and grid nudging was applied throughout the simulations to minimize the error growth. The comparisons of two simulations (using NARR and GFS IC/BC) showed substantial differences in predicted flow patterns, temperature and boundary layer characteristics, even though the simulations used identical physics options and nudging processes. Mercury episodes will be modeled using the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) with the different meteorological inputs. We intend to investigate the meteorological features associated with elevated mercury levels and their impacts on mercury modeling in synoptic settings of summer and spring seasons.