Model Estimation of Sulfate Aerosol Sources Collected at Cape Hedo during an Intensive Campaign in October-November, 2015

Abstract

An intensive observation campaign at Cape Hedo, Okinawa, Japan was conducted from late October to early November 2015 to investigate the behavior of long-range transported atmospheric pollutants. During this period, sulfate (SO 4 2-) was the dominant aerosol component. The sources of SO 4 2-were estimated by using the air quality model with the tagged tracer method. The main source of high SO 4 2-concentration varied day-to-day. When the westerly wind was dominant (October 27), the main source was anthropogenic SO 2 emissions in China. When the northerly wind prevailed (November 1), the impact of volcanoes in western Japan was significant and the conversion ratio from SO 2 to SO 4 2-was lowest, at less than 70%, because of the faster transport. During the latter part of the campaign, the northerly to easterly winds were prominent, and the impacts of Korea, Japan, and ships on SO 4 2-observed at Cape Hedo were also clear. When the contributions from Korea, Japan, and ships were the highest (November 4), the conversion ratio was also the highest, at greater than 95% because of long-range transport. The modeled sources of volcanoes and ship emissions corresponded well with the observed coarse-mode SO 4 2-and V/Mn ratio, respectively. The mutual evaluation of sources from model and observations enable SO 4 2-sources to be estimated with higher confidence.

Refinement of Modeled Aqueous-Phase Sulfate Production via the Fe- and Mn-Catalyzed Oxidation Pathway

“…The model showed intrusions of high SO 4 2− concentrations from the Asian continent. This result was consistent with our previous studies suggesting trans-boundary SO 4 2− air pollution [26][27][28][29][30]. The correlation between the daily values from the observations and the model are compared in the scatter plot in Figure 3a.…”

“…The development of trace elements in emission inventories and model evaluations is required. Our approach for Japan should be applied to China given that trans-boundary SO 4 2− may have an impact over East Asia [26][27][28][29][30]. The refinement of the modeled aqueous-phase Fe-and Mn-catalyzed oxidation by O 2 over China may further improve the model performance during winter over both China and downwind regions.…”

Toward Synchronous Evaluation of Source Apportionments for Atmospheric Concentration and Deposition of Sulfate Aerosol Over East Asia

“…CAMx was configured with 220 × 140 grid points, a 36 km horizontal resolution, and 37 nonuniformly spaced layers from the surface to 50 hPa, centered at 35°N and 115°E on a Lambert conformal projection (Figure a). An earlier version of the WRF‐CAMx modeling system has been applied to air quality research over East Asia in our previous studies (Itahashi, Hayami, & Uno, ; Itahashi, Hayami, et al, ; Itahashi, Hatakeyama, et al, ).…”

“…To evaluate the source apportionment, the Particulate Source Apportionment Technology (PSAT) algorithm in CAMx was used (Wagstrom et al, ). PSAT was used to research the source apportionment of SO 4 2− over East Asia with superior computational efficiency (Itahashi, Hayami, et al, ; Itahashi, Hatakeyama, et al, ). To track SO 4 2− , CAMx calculates the SO 2 tracer as SO2 i and the SO 4 2− tracer as PS4 i , where i ( i = 1, …, N ) indicates the source group (i.e., source region and category).…”

“…version of the WRF-CAMx modeling system has been applied to air quality research over East Asia in our previous studies Itahashi, Hayami, et al, 2017;Itahashi, Hatakeyama, et al, 2017). The WRF meteorological model was configured as follows in this study.…”