Submitted as: development and technical paper 04 May 2021

Submitted as: development and technical paper | 04 May 2021

Review status: this preprint is currently under review for the journal GMD.

Incorporation of volcanic SO2 emissions in the Hemispheric CMAQ (H-CMAQ) version 5.2 modeling system and assessing their impacts on sulfate aerosol over Northern Hemisphere

Syuichi Itahashi1, Rohit Mathur2, Christian Hogrefe2, Sergey L. Napelenok2, and Yang Zhang3 Syuichi Itahashi et al.
  • 1Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Abiko, Chiba 270–1194, Japan
  • 2Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, U.S.A.
  • 3Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, U.S.A.

Abstract. The state-of-the-science Community Multiscale Air Quality (CMAQ) Modeling System has recently been extended for hemispheric-scale modeling applications (referred to as H-CMAQ). In this study, satellite-constrained estimation of the degassing SO2 emissions from 50 volcanos over the northern hemisphere is incorporated into H-CMAQ, and their impact on tropospheric sulfate aerosol (SO42−) levels is assessed for 2010. The volcanic degassing improves predictions of observations from the Acid Deposition Monitoring Network in East Asia (EANET), the United States Clean Air Status and Trends Network (CASTNET), and the United States Integrated Monitoring of Protected Visual Environments (IMPROVE). Over Asia, the increased SO42− concentrations were seen to correspond to the locations of volcanoes, especially over Japan and Indonesia. Over the U.S.A., the largest impacts occurred over the central Pacific caused by including the Hawaiian Kilauea volcano while the impacts on the continental U.S.A. were limited to the western portion during summertime. The emissions of the Soufriere Hills volcano located on Montserrat Island in the Caribbean Ocean affected the southeastern U.S.A. during the winter season. The analysis at specific sites in Hawaii and Florida also confirmed improvements in regional performance for modeled SO42− by including volcanoes SO2 emissions. At the edge of the western U.S.A., monthly-averaged SO42− enhancements greater than 0.1 μg/m3 were noted within the boundary layer (defined as surface to 750 hPa) during June–September. Investigating the change on SO42− concentration throughout the free troposphere revealed that although the considered volcanic SO2 emissions occurred at or below the middle of free troposphere (500 hPa), compared to the simulation without the volcanic source, SO42− enhancements of more than 10 % were detected up to the top of the free troposphere (250 hPa). Our model simulations and comparisons with measurements across the Northern Hemisphere indicate that the degassing volcanic SO2 emissions are an important source impacting airborne sulfur budgets and should be considered in air quality model simulations assessing background SO42− levels and their source attribution.

Syuichi Itahashi et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-109', Anonymous Referee #1, 30 May 2021
  • RC2: 'Comment on gmd-2021-109', Anonymous Referee #2, 02 Jun 2021
  • CEC1: 'Comment on gmd-2021-109', Juan Antonio Añel, 29 Jun 2021

Syuichi Itahashi et al.

Syuichi Itahashi et al.


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Short summary
The Community Multiscale Air Quality (CMAQ) modeling system extended for hemispheric-scale applications (H-CMAQ) incorporated the satellite-constrained degassing SO2 emissions from 50 volcanos across the northern hemisphere. The impact on tropospheric sulfate aerosol (SO42−) is assessed for 2010. Although the considered volcanic emissions occurred at or below the middle of free troposphere (500 hPa), SO42− enhancements of more than 10 % were detected up to the top of free troposphere (250 hPa).