Multi‐Year Seasonal Trends in Sea Ice, Chlorophyll Concentration, and Marine Aerosol Optical Depth in the Bellingshausen Sea

Abstract

In the remote polar sea ice environment of the Bellingshausen Sea, the formation and presence of marine tropospheric aerosol is coupled with physical, chemical, and biological processes. Present in both the Antarctic and Arctic, sea ice habitats are among the largest ecosystems on our planet (Arrigo, 2014). They are subject to a number of physical processes due to the inherent temporality of high-latitude environments, from the seasonal dynamics of variable light availability, increases and decreases in sea ice extent and thickness, fluctuations in nutrient availability, and fluctuations in the timing and magnitude of primary

Wind‐Driven and Seasonal Effects on Marine Aerosol Production in the Bellingshausen Sea, Antarctica

“…They further surmised that this significant anticorrelation was due to the suppression of SSA during increased chlorophyll– a concentrations (chl‐ a ) and associated high surfactant concentrations in the sea surface microlayer (Dror et al., 2018; Modini et al., 2013). Contrasting this study, analyses of time‐lagged data binned by month in several high‐latitude studies show that Marine Aerosol Optical Depth (MAOD) (Dasarathy et al., 2021) and AOD increased alongside seasonal increases in chl‐ a and sea ice melt (Gabric et al., 2005, 2018). Those authors attributed a biological component of marine aerosol contributing to fluctuations in seasonal magnitudes of AOD.…”

“…Those authors attributed, to first order, variations in AOD C to variations in wind, but they found that summertime blooms masked the wind speed dependence (Dror et al., 2018). We considered whether the high‐latitude coastal region of the Bellingshausen Sea would show MAOD and AOD C suppression due to stronger biological seasonality as supported by prior studies (Dasarathy et al., 2021; Gabric et al., 2005, 2018). We used AOD C , a proxy for aerosol particles with radii >1 μm (most notably SSA in remote marine environments), as well as MAOD, a proxy for lower altitude marine aerosol particles with radii >100 nm to answer the following: (a) Do MAOD and AOD C correlate to wind speed across time scales in the Bellingshausen Sea region?…”

“…As in Dror et al (2018), we retrieved AOD C from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua. Using methods previously developed in Dasarathy et al (2021), we further examined MAOD, retrieved from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). AOD C is a measure of the coarse mode of aerosol particles (those with radii >1 μm) (Fitzgerald, 1991;Kleefeld, 2002;Sellegri et al, 2001).…”

“…Nevertheless, passive sensor retrievals have limitations, and in high-latitude environments these include the full omission of wintertime data due to lack of nighttime retrievals. To address these challenges, previously we developed a novel method of quantifying low-lying aerosols (Dasarathy et al, 2021). MAOD-retrieved in high-latitude winter despite lack of solar radiation--is used alongside AOD C to characterize these aerosols (For more information, see Section S1 in Supporting Information S1).…”

The representation of sea salt aerosols and their role in polar climate within CMIP6

“…For the purpose of this CMIP6 model evaluation, a proxy based on MODIS AOD and Angstrom exponent is therefore used to create a simple version of this missing product. A more refined dedicated polar marine AOD climatology product could be created by combining several satellite sources (Dror et al, 2018;Dasarathy et al, 2021;Atmoko & Lin, 2022) in future work. However, the Arctic time series obtained using the methodology described below (Section 3.2.2) is well in line with the SSaer AOD values reported in Xian et al (2022) for example, which are based on an ensemble of reanalyses.…”