Articles | Volume 17, issue 11
Atmos. Chem. Phys., 17, 6925–6955, 2017

Special issue: Global Mercury Observation System – Atmosphere...

Atmos. Chem. Phys., 17, 6925–6955, 2017

Research article 13 Jun 2017

Research article | 13 Jun 2017

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

Johannes Bieser1,2, Franz Slemr3, Jesse Ambrose4, Carl Brenninkmeijer3, Steve Brooks5,6, Ashu Dastoor7, Francesco DeSimone8, Ralf Ebinghaus1, Christian N. Gencarelli8, Beate Geyer1, Lynne E. Gratz9, Ian M. Hedgecock8, Daniel Jaffe4,10, Paul Kelley5,11, Che-Jen Lin12, Lyatt Jaegle21, Volker Matthias1, Andrei Ryjkov7, Noelle E. Selin13,14, Shaojie Song13, Oleg Travnikov15, Andreas Weigelt1,16, Winston Luke5, Xinrong Ren5,11,17, Andreas Zahn18, Xin Yang19, Yun Zhu20, and Nicola Pirrone22 Johannes Bieser et al.
  • 1Helmholtz Zentrum Geesthacht, 21052 Geesthacht, Germany
  • 2DLR – Deutsches Luft und Raumfahrtzentrum, Münchener Straße 20, 82234 Weßling, Germany
  • 3Max Planck Institute for Chemistry (MPI), Hahn-Meitner-Weg 1, 55128 Mainz, Germany
  • 4School of Science, Technology, Engineering and Mathematics, University of Washington-Bothell, Bothell, WA, USA
  • 5Air Resources Laboratory, National Oceanic and Atmospheric Administration, 5830 University Research Court, College Park, MD 20740, USA
  • 6Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee Space Institute, 411 BH Goethert Parkway, Tullahoma, TN 37388, USA
  • 7ECCC – Air Quality Research Division, Environment and Climate Change Canada, Dorval, Canada
  • 8CNR Institute of Atmospheric Pollution Research, Division of Rende, Rende, Italy
  • 9Environmental Program, Colorado College, Colorado Springs, CO, USA
  • 10School of Science, Technology, Engineering and Mathematics, University of Washington-Bothell, Bothell, WA, USA
  • 11Cooperative Institute for Climate and Satellites, University of Maryland, 5825 University Research Court, College Park, MD 20740, USA
  • 12Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas, USA
  • 13Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
  • 14Institute for Data, Systems, and Society, Massachusetts Institute of Technology, Cambridge, MA, USA
  • 15Meteorological Synthesizing Centre – East of EMEP, Moscow, Russia
  • 16Federal Maritime and Hydrographic Agency (BSH), Hamburg, Germany
  • 17Department of Earth, Ocean, and Atmospheric Science, Florida State University, 117 North Woodward Avenue, Tallahassee, FL 32306, USA
  • 18Institut für Meteorologie und Klimaforschung (IMK-ASF), Karlsruhe Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Leopoldshafen, Germany
  • 19British Antarctic Survey, Cambridge, UK
  • 20South China University of Technology, School of Environment and Energy, Guangzhou, China
  • 21University of Washington, Department of Atmospheric Sciences, Seattle, WA 98195, USA
  • 22CNR Institute of Atmospheric Pollution Research, Rome, Italy

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights.

The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

Short summary
We conducted a multi model study to investigate our ability to reproduce the vertical distribution of mercury in the atmosphere. For this, we used observational data from over 40 aircraft flights in EU and US. We compared observations to the results of seven chemistry transport models and found that the models are able to reproduce vertical gradients of total and elemental Hg. Finally, we found that different chemical reactions seem responsible for the oxidation of Hg depending on altitude.
Final-revised paper