TY - JOUR
T1 - Evaluation of CMAQ Coupled With a State-of-the-Art Mercury Chemical Mechanism (CMAQ-newHg-Br)
AU - Ye, Zhuyun
AU - Mao, Huiting
AU - Driscoll, Charles T.
AU - Wang, Yan
AU - Zhang, Yanxu
AU - Jaeglé, Lyatt
N1 - Funding Information:
This work was sponsored by the New York State Energy Research and Development Authority (NYSERDA) and the National Science Foundation of China grant 41475115. We thank R. Volkamer of University of Colorado for their BrO vertical profile measurement data. We are grateful to C. Hogrefe of US EPA for providing the 2010 WRF simulations. This work used XSEDE, which is supported by National Science Foundation grant ACI-1548562. We are grateful to the two anonymous reviewers for their thoughtful, detailed, constructive comments, which helped to improve the clarity of the paper. The observational ambient Hg data were downloaded from http://nadp.sws.uiuc.edu/amn/data.aspx (AMNet website) and http://www.eos.unh.edu/observatories/data.shtml (University of New Hampshire, 2016). Observational Hg wet deposition data were downloaded from http://nadp.sws.uiuc.edu/data/MDN/ (MDN website). Hg dry deposition data used for comparison were derived from Zhang et al. (2012a,), Yu et al. (), Risch et al. (), and Wang (2012).
PY - 2018/3
Y1 - 2018/3
N2 - Most regional three-dimensional chemical transport models neglect gaseous elemental mercury (GEM) oxidation by bromine (Br) radicals and Br chemistry. In this study, the Community Multiscale Air Quality model with its default mercury module (CMAQ-Hg) was modified by implementing a state-of-the-art algorithm depicting Hg reactions coupled with Br chemistry (CMAQ-newHg-Br). Using CMAQ-newHg-Br with initial and boundary concentrations (ICs and BCs) from global model output, we conducted simulations for the northeastern United States over March–November 2010. Simulated GEM mixing ratios were predominantly influenced by BCs and hence reflected significant seasonal variation that was captured in the global model output as opposed to a lack of seasonal variation using CMAQ-Hg's default constant BCs. Observed seasonal percentage changes (i.e., seasonal amplitude [=maximum – minimum] in percentage of the seasonal average) of gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were 76% and 39%, respectively. CMAQ-newHg-Br significantly improved the simulated seasonal changes in GOM and PBM to 43% and 23%, respectively, from 18% and 16% using CMAQ-Hg. CMAQ-newHg-Br reproduced observed Hg wet deposition with a remarkably low fractional bias (FB; 0.4%) as opposed to a −56% to 19% FB for CMAQ-Hg simulations. Simulated Hg dry deposition using CMAQ-newHg-Br excluding the GEM + OH reaction agreed well with studies using inferential methods and litterfall/throughfall measurements, and the discrepancy varied over 13%–42%. This study demonstrated the promising capability of CMAQ-newHg-Br to reproduce observed concentrations and seasonal variations of GEM, GOM and PBM, and Hg wet and dry deposition fluxes.
AB - Most regional three-dimensional chemical transport models neglect gaseous elemental mercury (GEM) oxidation by bromine (Br) radicals and Br chemistry. In this study, the Community Multiscale Air Quality model with its default mercury module (CMAQ-Hg) was modified by implementing a state-of-the-art algorithm depicting Hg reactions coupled with Br chemistry (CMAQ-newHg-Br). Using CMAQ-newHg-Br with initial and boundary concentrations (ICs and BCs) from global model output, we conducted simulations for the northeastern United States over March–November 2010. Simulated GEM mixing ratios were predominantly influenced by BCs and hence reflected significant seasonal variation that was captured in the global model output as opposed to a lack of seasonal variation using CMAQ-Hg's default constant BCs. Observed seasonal percentage changes (i.e., seasonal amplitude [=maximum – minimum] in percentage of the seasonal average) of gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were 76% and 39%, respectively. CMAQ-newHg-Br significantly improved the simulated seasonal changes in GOM and PBM to 43% and 23%, respectively, from 18% and 16% using CMAQ-Hg. CMAQ-newHg-Br reproduced observed Hg wet deposition with a remarkably low fractional bias (FB; 0.4%) as opposed to a −56% to 19% FB for CMAQ-Hg simulations. Simulated Hg dry deposition using CMAQ-newHg-Br excluding the GEM + OH reaction agreed well with studies using inferential methods and litterfall/throughfall measurements, and the discrepancy varied over 13%–42%. This study demonstrated the promising capability of CMAQ-newHg-Br to reproduce observed concentrations and seasonal variations of GEM, GOM and PBM, and Hg wet and dry deposition fluxes.
KW - Br chemistry
KW - CMAQ-Hg
KW - Hg wet and dry deposition
KW - atmospheric Hg modeling
UR - http://www.scopus.com/inward/record.url?scp=85045657622&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85045657622&partnerID=8YFLogxK
U2 - 10.1002/2017MS001161
DO - 10.1002/2017MS001161
M3 - Article
AN - SCOPUS:85045657622
VL - 10
SP - 668
EP - 690
JO - Journal of Advances in Modeling Earth Systems
JF - Journal of Advances in Modeling Earth Systems
SN - 1942-2466
IS - 3
ER -