10:15 AM - 10:30 AM
[ACC29-06] Variation in chemical form of aerosol deposited around southeastern Greenland in spring season during 1960-2015.
Keywords:Greenland, ice core, aerosol, micro-Raman
The ice samples were sublimated on Ni sheets in a clean booth under −22 degrees Celsius, and residual inclusions were analyzed. We analyzed 100 particles from spring samples. We identified CaSO4, Na2SO4, (NH4)2SO4, NaNO3, NH4NO3 and CaCO3 by Raman spectra. Sulfate/nitrate ratios gradually increase with depth direction. This trend is consistent with the decreasing trend of sulfate ion concentration (Iizuka et al., 2017). Moreover, (NH4)2SO4 is the major chemical form in the samples characterized by higher sulfate/nitrate ratios. Our back trajectory analyses using Hysplit suggest the air mass contribution from EU was higher during 60’s and 70’s. This higher contribution is possibly related to negative North Atlantic Oscillation (NAO-; Sodemann et al., 2008). From these results, we suggest that anthropogenic emission in EU before 70’s increased (NH4)2SO4 and sulfate depositions in SE Greenland. In contrast, sodium salts (Na2SO4 and NaNO3) decrease with depth direction. Atlantic Multidecadal Oscillation (AMO) changed from negative to positive after late 90’s. Sea salt emission in the North Atlantic around Greenland increases with SST during AMO+ (Li et al., 2015). We presumed that constant transportation of NaNO3 under AMO+ after late 90’s possibly maintained higher nitrate ions in the SE samples regardless of decreasing of anthropogenic NOx emissions.