| MSA (mainly derived from marine biogenic emissions) has been used to estimate the marine biogenic contribution frequently. MSA could form aerosols, these S-containing aerosols could influence the earth’s radiation balance by directly scattering solar radiation and act as cloud condensation nuclei (CCN) to influence cloud coverage and albedo, resulting in a negative feedback to climatic perturbations. Although there are many studies about MSA in Arctic and Antarctic were reported. However, most of reports about MSA were based upon land-based observations around the Arctic and Antarctic Ocean. Thus, more studies about MSA over the Arctic Ocean and Antarctic Ocean, are needed for a better understanding of biogenic sulfur emissions in the polar regions. Here we report and discuss the results of aerosol MSA in summertime taken during the Chinese National Arctic Research cruise (CHINARE2012,CHINARE2012and CHINARE11/12). Our goal is to investigate the spatial distributions of MSA and to explore the mechanisms and influencing factors of MSA the polar regions. Results from this work will also provide new data concerning MSA for model constraints. The major contents and results in this dissertation are listed below:During the fifth CHINARE in July to September2012, the aerosol MSA concentrations over Arctic Ocean varied considerably ranged from ND to229ng/m3, with an average of27±54ng/m (median:lOng/m). We found the distribution of aerosol MSA over the Arctic Ocean exhibited an obvious regional variations. Aerosol MSA in Arctic Ocean were mainly affected by biotic factors and abiotic factors. High values were generally observed in Norwegian Sea, this phenomenon was ascribed to high rates of phytoplankton primary productivity and DMS fluxes in this region, consistent with results of the previous studies. Sea ice also have a significant impact on MSA distributions, concentrations over the pack ice region in the central Arctic Ocean were generally lower than over the open waters at the ice edge in Chukchi Sea. Besides, we also found Physical factors could affect the distribution of MSA, higher MSA concentrations were associated with warmer sea surface temperature (SST), and a positive correlation between MSA and SST was observed, similar to the results of previous studies. The high MSA concentrations were found over the south of the60℃.When the southern ocean sea ice melts reach to the maximum, MSA and Nss-SO42-concentrations in atmospheric aerosol were increased. In addition to the high concentration of MSA over the southern ocean, the concentrations of Nss-SO42-was also high. And the high concentrations of MSA and Nss-SO42-may be ascribed to high primary production and strong air-sea exchange in this region.At the global scale, there is an upward trend of MSA concentrations from low latitude to high latitude, while Nss-SO42-had the opposite trend. Aerosol Nss-SO42-concentrations in low latitudes of the northern hemisphere were mainly affected by anthropogenic emissions. Besides, Nss-SO42-and NO3-have a good correlation (R2=0.8, P<0.001). This phenomenon is mainly ascribed to the increase of the concentration of nitrogen oxides in the atmosphere which could improve the oxidation efficiency of DMS.MSA/Nss-SO42-(R) showed different distribution between the northern hemisphere and the southern hemisphere. R value was relatively low, because there are quite non sea salt sulfate derived from pollutants produced by human activity in the northern hemisphere. |
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