Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS04] Atmospheric Chemistry

Thu. May 30, 2019 10:45 AM - 12:15 PM 102 (1F)

convener:Tomoki Nakayama(Graduate School of Fisheries and Environmental Sciences, Nagasaki University), Yoko Iwamoto(Graduate School of Biosphere Science, Hiroshima University), Sakae Toyoda(Department of Chemical Science and Engineering, Tokyo Institute of Technology), Nawo Eguchi(Kyushu University), Chairperson:Fumikazu Taketani(海洋研究開発機構), Michihiro Mochida(名古屋大学)

11:15 AM - 11:30 AM

[AAS04-24] Roles of heterogeneous reactions in the tropospheric chemistry: a global modeling study

*Phuc Thi Minh Ha1, Fumikazu Taketani2, Yugo Kanaya2, Kengo Sudo1,2 (1.Graduate School of Environmental Studies, Nagoya University, 2.Research and Development Center for Global Change, JAMSTEC)

Keywords:heterogeneous reaction, chemical climate model, North Pacific

Heterogeneous reactions in the atmosphere largely affect air quality and climate by changing tropospheric photochemical processes involving gases like O3, HOx, NOx, HNO3, CO, VOCs, and aerosols.
There are many previous studies on the effects of heterogeneous reactions at regional to global scales using direct measurements, remote sensing, and simulation. For the atmospheric chemistry simulation, there is a large uncertainty from the treatment of the heterogeneous reactions in the model due to the still insufficient understanding of the mechanism of heterogeneous reactions.
This study is intended to understand the roles of the heterogeneous reactions in the global tropospheric chemistry using a chemistry-climate model CHASER (MIROCESM) (Sudo et al., 2011) which includes more than 250 chemical reactions in the troposphere and stratosphere with more than 70 chemical species. This model also includes aerosol components (SPRINTARS) for sulfate, nitrate, BC, POA/SOA, dust, and sea-salt; formation of nitrate and SOA, and ageing of BC are calculated tightly linked to the chemistry in CHASER. The present version of CHASER considers heterogeneous reactions of N2O5, HO2, RO2, and HCHO for surfaces of the individual aerosol components and cloud particles.
The model simulation is validated with the observational data from EANET, EMEP and the ship-based observation. Our performed sensitivity simulations with respect to the heterogeneous reactions show that the impacts of the N2O5 heterogeneous reaction may not be as large as previously reported; surface concentrations of NOx, O3 and OH are only reduced by 1.6%, 2.2%, 2.6%, respectively, in global mean (in regional, at most, 23%, 5.4%, and 12.8%). Whereas, the HO2 reaction (to form H2O2) can cause a significant effect on distributions of O3 and related species (NOx, O3, OH are changed by 68.7%, -21.5% and -70.1%). In addition to the polluted areas in China and India, we found that in the North Pacific region the heterogeneous reactions can play a critical role in the concentrations of NOx, O3, CO, OH, HO2 (up to 69%, 21%, 7%, 70%, 81%, respectively). The possible large impacts of the heterogeneous reactions are also verified with the ship-based observational data for the North Pacific and Alaska regions.