You are here:
An Analysis of Simulated Wet Deposition of Mercury from the North American Mercury Model Intercomparison Study
Citation:
BULLOCK, R., D. ATKINSON, T. BRAVERMAN, K. Civerolo, A. Dastoor, D. Davignon, J. Ku, K. Lohman, T. MYERS, R. J. Park, C. SEIGNEUR, N. E. SELIN, G. Sistla, AND K. Vijayaraghavan. An Analysis of Simulated Wet Deposition of Mercury from the North American Mercury Model Intercomparison Study. JOURNAL OF GEOPHYSICAL RESEARCH: ATMOSPHERES. American Geophysical Union, Washington, DC, 114(D08301):1-12, (2009).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling Division (AMD) conducts research in support of EPA′s mission to protect human health and the environment. AMD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
A previous intercomparison of atmospheric mercury models in North America has been extended to compare simulated and observed wet deposition of mercury. Three regional-scale atmospheric mercury models were tested; CMAQ, REMSAD and TEAM. These models were each employed using three sets of lateral boundary conditions to test their sensitivity to intercontinental transport of mercury. The same meteorological and pollutant emission data were used in each simulation. Observations of wet deposition were obtained from the NADP's Mercury Deposition Network. The regional models can explain 50-70% of the site-to-site variance in annual mercury wet deposition. CMAQ was found to have slightly superior agreement to observations of annual mercury deposition flux in terms of the mean value for all monitoring sites, but REMSAD showed the best correlation when measured by the coefficient of determination (r2). With the exception of one CMAQ simulation, all of the models tended to simulate more wet deposition of mercury than was observed. TEAM exceeded the observed average annual wet deposition by 50% or more in all three of its simulations. CMAQ and REMSAD were better able to reproduce the observed seasonal distribution of mercury wet deposition than TEAM, but TEAM showed the highest correlation for weekly wet deposition samples. An analysis of model accuracy at each observation site showed no obvious geographic patterns for correlation, bias or error. Adjusting simulated mercury deposition based on the difference between observed and simulated precipitation data improved the correlation and error scores for all of the models.
