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A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry.
Environ Sci Technol. 2019 05 07; 53(9):5052-5061.ES

Abstract

Air-sea exchange of mercury (Hg) is the largest flux between Earth system reservoirs. Global models simulate air-sea exchange based either on an atmospheric or ocean model simulation and treat the other media as a boundary condition. Here we develop a new modeling capability (NJUCPL) that couples GEOS-Chem (atmospheric model) and MITgcm (ocean model) at the native hourly model time step. The coupled model is evaluated against high-frequency simultaneous measurements of elemental mercury (Hg0) in both the atmosphere and surface ocean obtained during five published cruises in the Atlantic, Pacific, and Southern Oceans. Results indicate that the calculated global Hg net evasion flux is 12% higher for the online model than the offline model. We find that the coupled online model captures the spatial pattern of the observations; specifically, it improves the representation of peak seawater Hg0 (Hg0aq) concentration associated with enhanced precipitation in the intertropical convergence zone in both the Atlantic and the Pacific Oceans. We investigate the causes of the observed Hg0aq peaks with two sensitivity simulations and show that the high Hg0aq concentrations are associated with elevated convective cloud mass flux and bromine concentrations in the tropical upper troposphere. Observations of elevated Hg0aq concentrations in the western tropical Pacific Ocean merit further study involving BrO vertical distribution and cloud resolving models.

Authors+Show Affiliations

Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences , Nanjing University , Nanjing , Jiangsu 210023 , China.Department of Atmospheric Sciences , University of Washington , Seattle , Washington 98195 , United States.Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences , University of Science and Technology of China , Hefei , Anhui 230026 , China.Anhui Province Key Laboratory of Polar Environment and Global Change, School of Earth and Space Sciences , University of Science and Technology of China , Hefei , Anhui 230026 , China.Department of Marine Chemistry , Leibniz Institute for Baltic Sea Research , Rostock-Warnemünde 18119 , Germany.Department of Environmental Science and Analytical Chemistry , Stockholm University , Stockholm 10691 , Sweden.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30946578

Citation

Zhang, Yanxu, et al. "A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights Into Wet Deposition and Atmospheric Redox Chemistry." Environmental Science & Technology, vol. 53, no. 9, 2019, pp. 5052-5061.
Zhang Y, Horowitz H, Wang J, et al. A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry. Environ Sci Technol. 2019;53(9):5052-5061.
Zhang, Y., Horowitz, H., Wang, J., Xie, Z., Kuss, J., & Soerensen, A. L. (2019). A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry. Environmental Science & Technology, 53(9), 5052-5061. https://doi.org/10.1021/acs.est.8b06205
Zhang Y, et al. A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights Into Wet Deposition and Atmospheric Redox Chemistry. Environ Sci Technol. 2019 05 7;53(9):5052-5061. PubMed PMID: 30946578.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A Coupled Global Atmosphere-Ocean Model for Air-Sea Exchange of Mercury: Insights into Wet Deposition and Atmospheric Redox Chemistry. AU - Zhang,Yanxu, AU - Horowitz,Hannah, AU - Wang,Jiancheng, AU - Xie,Zhouqing, AU - Kuss,Joachim, AU - Soerensen,Anne L, Y1 - 2019/04/12/ PY - 2019/4/5/pubmed PY - 2019/9/19/medline PY - 2019/4/5/entrez SP - 5052 EP - 5061 JF - Environmental science & technology JO - Environ Sci Technol VL - 53 IS - 9 N2 - Air-sea exchange of mercury (Hg) is the largest flux between Earth system reservoirs. Global models simulate air-sea exchange based either on an atmospheric or ocean model simulation and treat the other media as a boundary condition. Here we develop a new modeling capability (NJUCPL) that couples GEOS-Chem (atmospheric model) and MITgcm (ocean model) at the native hourly model time step. The coupled model is evaluated against high-frequency simultaneous measurements of elemental mercury (Hg0) in both the atmosphere and surface ocean obtained during five published cruises in the Atlantic, Pacific, and Southern Oceans. Results indicate that the calculated global Hg net evasion flux is 12% higher for the online model than the offline model. We find that the coupled online model captures the spatial pattern of the observations; specifically, it improves the representation of peak seawater Hg0 (Hg0aq) concentration associated with enhanced precipitation in the intertropical convergence zone in both the Atlantic and the Pacific Oceans. We investigate the causes of the observed Hg0aq peaks with two sensitivity simulations and show that the high Hg0aq concentrations are associated with elevated convective cloud mass flux and bromine concentrations in the tropical upper troposphere. Observations of elevated Hg0aq concentrations in the western tropical Pacific Ocean merit further study involving BrO vertical distribution and cloud resolving models. SN - 1520-5851 UR - https://www.unboundmedicine.com/medline/citation/30946578/A_Coupled_Global_Atmosphere_Ocean_Model_for_Air_Sea_Exchange_of_Mercury:_Insights_into_Wet_Deposition_and_Atmospheric_Redox_Chemistry_ L2 - https://doi.org/10.1021/acs.est.8b06205 DB - PRIME DP - Unbound Medicine ER -