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INTERCOMPARISON STUDY OF ATMOSPHERIC MERCURY MODELS: 2. MODELING RESULTS VS. LONG-TERM OBSERVATIONS AND COMPARISON OF COUNTRY ATMOSPHERIC BALANCES
Citation:
RYABOSHAPKO, A., R. BULLOCK, J. CHRISTENSEN, M. COHEN, A. DASTOOR, I. ILYIN, G. PETERSEN, D. SYRAKOV, R. S. ARTZ, D. DAVIGNON, R. R. DRAXLER, AND J. MUNTHE. INTERCOMPARISON STUDY OF ATMOSPHERIC MERCURY MODELS: 2. MODELING RESULTS VS. LONG-TERM OBSERVATIONS AND COMPARISON OF COUNTRY ATMOSPHERIC BALANCES. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier Science Ltd, New York, NY, 377(2-3):319-333, (2007).
Impact/Purpose:
The objectives of this task are to continue development and improvement of EPA's mesoscale (regional through urban scale) air quality modeling systems, such as the Community Multiscale Air Quality (CMAQ) model, as air quality management and NAAQS implementation tools. This task focuses on needed research and development of air quality models targeted for a major CMAQ model release in FY08. Model development for a broad scope of application is envisioned. For example, CMAQ will need to be able to simulate air quality feedbacks to meteorology and climate as well as intercontinental transport. The 2008 release of CMAQ is timed to coincide with EPA/OAR's and the states' needs for an improved model for assessments of progress (mid-course corrections) in the post-SIP submittal timeframe.
Description:
Five regional scale models with a horizontal domain covering the European continent and its surrounding seas, two hemispheric and one global scale model participated in the atmospheric Hg modelling intercomparison study. The models were compared between each other and with available measurements from 11 monitoring stations of the EMEP measurement network. Because of very limited number of long-term measurements of Hg available more attention was paid to intercomparison of modelling results. Monthly and annually averaged values of Hg concentrations and depositions as well as items of the Hg atmospheric balances for individual European countries were compared. The models demonstrated good agreement (within ±20%) between annual modelled and observed values of gaseous elemental Hg. Modelled values of Hg wet deposition in Western and Central Europe agreed with the observations within ±45%. Probability to predict wet depositions within a factor of 2 with regard to measurements was 50-70% for all the models. The scattering of modelling results for dry depositions of Hg was more significant (up to ±50% at the annual scale and even higher for monthly data). Contribution of dry deposition to the total Hg deposition was estimated at 30% or higher with elevated dry deposition fluxes during summer time. The participating models agree predicting transboundary pollution for individual countries within ±60% at the monthly scale and within ±30% at the annual scale. All the models predict that the major part of national anthropogenic emissions of Hg is transported outside the country territory.