The North American Mercury Model Intercomparison Study (NAMMIS): Study description and model‐to‐model comparisons

Abstract

[ 1 ] An atmospheric mercury model intercomparison study has been conducted to compare three regional-scale atmospheric mercury models, CMAQ, REMSAD, and TEAM, in atightly constrained testing environment with afocus on North America. Each of these models used the same horizontal modeling grid, pollutant emission information, modeled meteorology,a nd boundary conditions to the greatest extent practical. Three global-scale atmospheric mercury models were applied to define three separate initial condition and boundary condition (IC/BC) data sets for elemental mercury,r eactive gaseous mercury,a nd particulate mercury air concentrations for use by the regional-scale models. The monthly average boundary concentrations of some mercury species simulated by the global models were found to vary by more than afactor of 10, especially at high altitudes. CMAQ, REMSAD, and TEAM were each applied three times, once for each IC/BC data set, to simulate atmospheric mercury transport and deposition during 2001. This paper describes the study design and shows qualitative model-to-model comparisons of simulation results on an annual basis. The air concentration patterns for mercury simulated by the regional-scale models showed significant differences even when the same IC/BC data set was used. Simulated wet deposition of mercury was strongly influenced by the shared precipitation data, but differences of over 50% were still apparent. Simulated dry deposition of mercury was found to vary between the regional-scale models by nearly af actor of 10 in some locations. Further analysis is underway to perform statistical comparisons of simulated and observed mercury wet deposition using weekly and annual sample integration periods.

An assessment of atmospheric mercury in the Community Multiscale Air Quality (CMAQ) model at an urban site and a rural site in the Great Lakes Region of North America

“…A number of studies have used these data to evaluate CMAQ-Hg (Bash, 2010;Bullock and Brehme, 2002;Bullock et al, 2008Bullock et al, , 2009Gbor et al, 2006Gbor et al, , 2007Lin et al, 2007;Lin and Tao, 2003;Pongprueksa et al, 2008;Sunderland et al, 2008;Vijayaraghavan et al, 2007), and other atmospheric chemistry models that include mercury (Cohen et al, 2004;Holmes et al, 2010;Sanei et al, 2010;Seigneur et al, 2003;Selin and Jacob, 2008;Vijayaraghavan et al, 2008). Until recently, most studies that evaluate model estimates of ambient mercury compare with Total Gaseous Mercury (TGM) and/or Hg 0 (Gbor et al, 2006(Gbor et al, , 2007Holmes et al, 2010;Lin and Tao, 2003;Lohman et al, 2008;Selin et al, 2007;Soerensen et al, 2010;Wen et al, 2011).…”

Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

“…The model is based on a three-dimensional Eulerian atmospheric chemistry and transport modeling system that simulates Hg, ozone, particulate matter, acid deposition, and visibility simultaneously. The model components and scientific backgrounds have been documented elsewhere (Bullock and Brehme, 2002;Bullock et al, 2008;Travnikov et al, 2010). A spin-up period of 10 days is used to eliminate the impact of initial conditions for atmospheric oxidants (O 3 and OH) that react with mercury.…”

“…Since then, extensive model intercomparison studies have been performed to evaluate and improve the original models (Bullock et al, 2008;Ryaboshapko et al, 2002Ryaboshapko et al, , 2007a. However, until today, we have not fully understood all parts of the global mercury cycle.…”

A new mechanism for atmospheric mercury redox chemistry: implications for the global mercury budget

“…Previous work assumed gas-phase OH and ozone to be the dominant Hg 0 oxidants (Bergan and Rodhe, 2001;Dastoor and Larocque, 2004;Selin et al, 2007;Bullock et al, 2008;Travnikov and Ilyin, 2009;De Simone et al, 2014;Gencarelli et al, 2014). It is now well established that the corresponding HgOH and HgO products are too thermally unstable to enable oxidation to Hg II under atmospheric conditions Goodsite et al, 2004;Calvert and Lindberg, 2005;Hynes et al, 2009;Jones et al, 2016).…”