A Multiyear Southern Ocean-scale EOF analysis between Surface Ocean Parameters and Biogenic Aerosol Presence

Abstract:

Marine biogenic aerosol formation is influenced by the activity of primary producers and fluctuations in sea ice. In the Southern Ocean, remote sensing-based studies focused on aerosol formation, distribution, and links to chlorophyll-a (chl-a) concentration and sea ice have thus far predominantly used passive satellite retrievals of aerosol optical properties. However, these can be subject to and biased by cloud presence, signal uncertainties, and lack of retrievals in high latitude wintertime. To address these concerns, we have developed a novel method of quantifying tropospheric marine aerosol with the NASA Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), which we term clean marine optical depth (CMOD). Using CMOD, we are undertaking a multi-year satellite remote sensing study using NASA CALIPSO and the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua to examine the large-scale variability between surface ocean and lower-atmosphere dynamics. We examine the spatial and temporal variability of CMOD, chl-a concentration, and sea ice presence from 2007 – 2019 across the spatial grid from 50S – 90S and 180W – 180E. Across this spatial grid, dipole interactions across these variables are evident between different basins in the Southern Ocean. Furthermore, the first mode of our EOF describes ~26%, ~35%, and ~30% of the variance in chl-a, CMOD, and sea ice, respectively. Our work thus far suggests that large-scale spatiotemporal variability is dominated by basin-scale processes in the Southern Ocean. Further work will examine linkages between these patterns and modes of climate variability including the El Niño-Southern Oscillation (ENSO), the Southern Annular Mode (SAM), and the Pacific Decadal Oscillation (PDO).