Index Geophysics

Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

For oceans to become a significant source of primary organic aerosol, sea spray must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic fraction of sea spray aerosol (OC_ss). To test this hypothesis, we developed a new marine primary organic aerosol emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-<i>a</i>, dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll-<i>a</i> concentration ([Chl-<i>a</i>]) are the most consistent predictors of OC_ss. This relationship, combined with the published aerosol size dependence of OC_ss, resulted in a new parameterization for the organic carbon fraction of sea spray. Global marine primary organic emission is investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-<i>a</i>], and modeled 10 m winds. Analysis of model simulations show that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.1 to 5.3 Tg C yr⁻¹. This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere.

Gantt, B.

Meskhidze, N.

2018-08-11

Text

application/pdf

10.5194/acpd-11-425-2011

https://acp.copernicus.org/preprints/acp-2010-760/

eISSN: 1680-7324

eng