Satellite assessment of sea spray aerosol productivity: Southern Ocean case study. Issue 2 (25th January 2016)

• Record Type: Journal Article
• Authors: Witek, Marcin L.; Diner, David J.; Garay, Michael J.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 2(2016)
• Page Start: 872
• Page End: 894
• Publication Date: 2016-01-25
• Subjects: sea spray aerosol -- MISR -- MODIS -- AOD -- SSA emission parameterization -- sea surface temperature; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2015JD023726
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Despite many years of observations by multiple sensors, there is still substantial ambiguity regarding aerosol optical depths (AOD) over remote oceans, in particular, over the pristine Southern Ocean. Passive satellite retrievals (e.g., Multiangle Imaging Spectroradiometer (MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS)) and global aerosol transport models show a distinct AOD maximum around the 60°S latitude band. Sun photometer measurements performed by the Maritime Aerosol Network (MAN), on the other hand, indicate no increased AODs over the Southern Ocean. In this study elevated Southern Ocean AODs are examined from the modeling perspective. The primary aerosol component over the Southern Ocean is sea spray aerosol (SSA). Multiple simulations of SSA concentrations and optical depths are carried out using a single modeling framework, the Navy Aerosol Analysis and Prediction System (NAAPS) model. Several SSA emission functions are examined, including recently proposed formulations with sea surface temperature corrections. The differences between NAAPS simulations are primarily due to different SSA emission formulations. The results are compared against satellite‐derived AODs from the MISR and MODIS instruments. MISR and MODIS AOD retrievals are further filtered to eliminate retrievals potentially affected by cloud contamination and cloud adjacency effects. The results indicate a very large impact of SSA emission parameterization on the simulated AODs. For some scenarios, the Southern Ocean AOD maximum almost completely disappears. Further MISR and MODIS AOD quality screening substantially improves model/satellite agreement. Based on these comparisons, an optimal SSA emission function for global aerosol transport models is recommended. Key Points: Satellite AOD retrievals are used to effectively evaluate different SSA emission parameterizations Recommended SSA emission function is Sofiev et al. (2011) with Jaegle et al. (2011) SST scaling Model agreement with satellite AOD is improved after SST influence on SSA emission is factored in