Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6339131 | Atmospheric Environment | 2014 | 11 Pages |
Abstract
Atmospheric concentrations of non-sea-salt sulfate (nss-SO42â) and methanesulfonic acid (MSA) were measured over the Pacific Ocean between 48°N and 55°S during the KH-08-2 and MR08-06 cruises in summers of 2008 and 2009, in order to investigate spatial distributions of each species and MSA/nss-SO42â ratio. In the subarctic western North Pacific, mean concentrations of nss-SO42â and MSA in bulk (fine + coarse) aerosols were 1.1 μg mâ3 and 0.061 μg mâ3, whereas those in the South Pacific were 0.25 μg mâ3 and 0.043 μg mâ3, respectively. In the subtropical western North Pacific, it was observed that nss-SO42â concentration sharply increased from 0.45 μg mâ3 up to 4.2 μg mâ3 under the dominant influence of the Kilauea volcano, while that of MSA remained low. Mean MSA/nss-SO42â ratio observed in the South Pacific was approximately 3.7 times higher than that in the subarctic western North Pacific, although the mean MSA concentration in the subarctic western North Pacific was a factor of 1.4 higher than that in the South Pacific. The distributions of nss-SO42â, MSA, and MSA/nss-SO42â ratio suggested that aerosol nss-SO42â plays a key role in the latitudinal variation in MSA/nss-SO42â ratio over the North and South Pacific during summer periods, and that high MSA concentrations in the subarctic western North Pacific and the South Pacific were related to high biological productivity and low air temperature. During the cruises, an inverse relationship (r = â0.72, p < 0.01) was observed between satellite-derived chlorophyll a concentration and air temperature, showing that high biological productivity occurred at high latitudes, where air temperature were relatively low, in both hemispheres during the summer periods. Although both MSA concentration and MSA/nss-SO42â ratio showed inverse and positive relationships with air temperature and chlorophyll a concentration, respectively, the correlations between these variables were weak, suggesting that the distributions of MSA concentration and MSA/nss-SO42â ratio over the North and South Pacific during the summer periods were influenced by more complex factors. Estimates using the MSA/nss-SO42â ratios measured in different latitude regions in the Pacific Ocean indicated that the contributions from biogenic sources accounted for 9.6-58% of the total nss-SO42â in aerosols collected in the subarctic western North Pacific, 15-85% in the subtropical western North Pacific, 10-70% in the central North Pacific, and 12-97% in the South Pacific, showing strong influence of anthropogenic nss-SO42â in the subarctic western North Pacific despite the higher mean concentration of MSA in the subarctic western North Pacific than in the South Pacific.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Atmospheric Science
Authors
Jinyoung Jung, Hiroshi Furutani, Mitsuo Uematsu, Jisoo Park,