Biogenic aerosol in central East Antarctic Plateau as a proxy for the ocean-atmosphere interaction in the Southern Ocean

Ten years of data of biogenic aerosol (methane sulfonic acid, MSA, and non-sea salt sulfate, nssSO(4)(2-)) collected at Concordia Station in the East Antarctic plateau (75 degrees 06' S.123 degrees 20' E) are interpreted as a function of the Southern Annular Mode (SAM), Chlorophyll-a concentration (Chl-a; a proxy for phytoplankton biomass), sea ice extent and area It is possible to draw three different scenarios that link these parameters in early, middle, and late summer. In early summer, the biogenic aerosol is significantly correlated to sea ice retreats through the phytoplankton biomass increases. Chl-a shows a significant correlation with nssSO(4)(2-) in the finest fraction (< 1 mu m). In contrast, only Chl-a in West Pacific and Indian Ocean sectors correlates with MSA in the coarse fraction. The transport routes towards the inner Antarctic plateau and aerosol formation processes could explain the different correlation patterns of the two compounds both resulting from the DMS oxidation. In mid-summer, Chl-a concentrations are at the maximum and are not related to sea ice melting. Due to the complexity of transport processes of air masses towards the Antarctic plateau, the MSA concentrations are low and not related to Chl-a concentration. In late summer, MSA and nssSO(4)(2-) present the highest concentrations in their submicrometric aerosol fraction, and both are significantly correlated with Chl-a but not with the sea ice. In early and mid-summer, the enhanced efficiency of transport processes from all the surrounding oceanic sectors with air masses traveling at low elevation can explain the highest concentrations of nssSO(4)(2-) and especially MSA. Finally, considering the entire time series, MSA shows significant year-to-year variability. This variability is significantly correlated with SAM but with a different time lag in early (0-month lag) and late summer (4-months lag). This correlation likely occurs through the effect of the SAM on phytoplankton blooms. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Based on the interpretation of ten years of biogenic aerosol data collected at Concordia Station in the East Antarctic plateau, three different scenarios can be drawn that are linked to sea ice, chlorophyll-a concentration, and the Southern Annular Mode. In early summer, biogenic aerosol is significantly correlated with sea ice retreats and increased phytoplankton biomass. In mid-summer, aerosol concentrations are low and not related to sea ice melting. In late summer, aerosol concentrations are highest and correlated with chlorophyll-a, but not sea ice. Additionally, there is significant year-to-year variability in aerosol concentrations, which is correlated with the Southern Annular Mode.