Wind‐Driven and Seasonal Effects on Marine Aerosol Production in the Bellingshausen Sea, Antarctica. Issue 3 (8th February 2023) - Dasarathy, S.
Abstract: We assessed satellite‐retrieved marine aerosol in the western Antarctic Peninsula (WAP) across a 12‐year period from coarse‐mode aerosol optical depth (AODC ), often used as a proxy for sea spray aerosol (SSA), and marine aerosol optical depth (MAOD), a newly developed proxy for tropospheric marine aerosol. Across open ocean to coastal regions, daily fluctuations in nighttime and daytime winds, respectively, drove increasing MAOD and AODC . MAOD depicted strong correlations with wind speed across open ocean and weak correlations in coastal regions. In the open ocean, AODC exhibited a very weak significant correlation to wind speed and a weak significant correlation to sea surface temperature (SST). We thus observed that warmer SST enhanced the production of SSA, supporting prior studies. This is the first study to assess patterns of AODC in the WAP. In contrast to the tropical Pacific, seasonal patterns showed that biological activity likely contributed toward MAOD and AODC magnitudes. Plain Language Summary: The production of marine aerosol in the Bellingshausen Sea of the western Antarctic is coupled to the environment. Processes driving marine aerosol include wind speed, which produces sea spray aerosol (SSA), sea surface temperature (SST), which can enhance the production of SSA, and seasonal dynamics of sea ice melt and phytoplankton blooms, which can contribute to production of biogenic sources of marine aerosol. To study these drivers in closer detail, we used two specialized proxies of marine aerosol concentration: coarse‐mode Aerosol Optical Depth (AODC ), a proxy for SSA, and Marine Aerosol Optical Depth (MAOD) a proxy for low‐altitude marine aerosol. We examined MAOD and AODC from 2007 to 2018 and found that wind speed was a driver of day‐to‐day fluxes in marine aerosol. In contrast to the tropical Pacific in which enhanced biological activity suppresses SSA particle production, we did not observe lessening of MAOD and AODC magnitudes during the biologically productive austral summertime. In fact, summertime MAOD exhibited a weak significant correlation to daily wind speed in the coastal ocean despite a lack of significance in wintertime. This work enriches our knowledge of biotic and abiotic drivers of marine aerosol in high‐latitude environments. Key Points: The open ocean and coastal Bellingshausen Sea show weak correlations of marine aerosol optical depth (MAOD) to daily winds AODC exhibits weak correlations to sea surface temperature (SST) in the open ocean and very weak correlations to daily wind speed across all regions Seasonal increases in MAOD dependence on daily wind speed is likely associated with higher biological activity in summer