Abstract
Abstract. The Model Inter-Comparison Study for Asia (MICS-Asia) phase III was conducted to promote understanding of regional air quality and climate change in Asia, which have received growing attention due to the huge amount of anthropogenic emissions worldwide. This study provides an overview of acid deposition. Specifically, dry and wet deposition of the following species was analyzed: S (sulfate aerosol, sulfur dioxide (SO2), and sulfuric acid (H2SO4)), N (nitrate aerosol, nitrogen monoxide (NO), nitrogen dioxide (NO2), and nitric acid (HNO3)), and A (ammonium aerosol and ammonia (NH3)). The wet deposition simulated by a total of nine models was analyzed and evaluated using ground observation data from the Acid Deposition Monitoring Network in East Asia (EANET). In the phase III study, the number of observation sites was increased from 37 in the phase II study to 54, and southeast Asian countries were newly added. Additionally, whereas the analysis period was limited to representative months of each season in MICS-Asia phase II, the phase III study analyzed the full year of 2010. The scope of this overview mainly focuses on the annual accumulated deposition. In general, models can capture the observed wet deposition over Asia but underestimate the wet deposition of S and A, and show large differences in the wet deposition of N. Furthermore, the ratio of wet deposition to the total deposition (the sum of dry and wet deposition) was investigated in order to understand the role of important processes in the total deposition. The general dominance of wet deposition over Asia and attributions from dry deposition over land were consistently found in all models. Then, total deposition maps over 13 countries participating in EANET were produced, and the balance between deposition and anthropogenic emissions was calculated. Excesses of deposition, rather than of anthropogenic emissions, were found over Japan, northern Asia, and southeast Asia, indicating the possibility of long-range transport within and outside of Asia, as well as other emission sources. To improve the ability of models to capture the observed wet deposition, two approaches were attempted, namely, ensemble and precipitation adjustment. The ensemble approach was effective at modulating the differences in performance among models, and the precipitation-adjusted approach demonstrated that the model performance for precipitation played a key role in better simulating wet deposition. Finally, the lessons learned from the phase III study and future perspectives for phase IV are summarized.
Highlights
With recent increases in anthropogenic emissions, Asia has experienced the highest atmospheric acid deposition worldwide (Vet et al, 2014)
Observation datasets of sulfur dioxide (SO2) and sulfate aerosol concentrations and wet sulfate aerosol (SO24−) deposition were prepared by a cooperative monitoring network in eastern Asia (Fujita et al, 2000), and a total of 18 sites located in China, Taiwan, Republic of Korea, and Japan were compared with models
3.1 Evaluation of precipitation In MICS-Asia phase III, the meteorological field was simulated by Weather Research and Forecasting (WRF) for models M1, M2, M4, M5, M6, M11, and M12, by Goddard Earth Observing System 5 (GEOS-5) for model M13, and by Regional Atmospheric Modeling System (RAMS) for model M14
Summary
With recent increases in anthropogenic emissions, Asia has experienced the highest atmospheric acid deposition worldwide (Vet et al, 2014). Observation datasets of sulfur dioxide (SO2) and sulfate aerosol concentrations and wet sulfate aerosol (SO24−) deposition were prepared by a cooperative monitoring network in eastern Asia (Fujita et al, 2000), and a total of 18 sites located in China, Taiwan, Republic of Korea, and Japan were compared with models. The EANET observation data of wet deposition at 37 sites were compared with models (Wang et al, 2008). The models generally reproduced acid deposition in China, Republic of Korea, Japan, and southeast Asia but could not accurately describe deposition in inland areas such as Mongolia and Russia. These differences were attributed to differences in meteorology, chemical mechanisms, and deposition parameterizations.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have