A sea-state based source function for size- and composition-resolved marine aerosol production

M S Long,W C Keene,D J Erickson,H Maring,D J Kieber

doi:10.5194/acp-11-1203-2011

Abstract

Abstract. A parameterization for the size- and composition-resolved production fluxes of nascent marine aerosol was developed from prior experimental observations and extrapolated to ambient conditions based on estimates of air entrainment by the breaking of wind-driven ocean waves. Production of particulate organic carbon (OCaer) was parameterized based on Langmuir equilibrium-type association of organic matter to bubble plumes in seawater and resulting aerosol as constrained by measurements of aerosol produced from productive and oligotrophic seawater. This novel approach is the first to parameterize size- and composition-resolved aerosol production based on explicit evaluation of wind-driven air entrainment/detrainment fluxes and chlorophyll-a as a proxy for surfactants in surface seawater. Production fluxes were simulated globally with an eight aerosol-size-bin version of the NCAR Community Atmosphere Model (CAM v3.5.07). Simulated production fluxes fell within the range of published estimates based on observationally constrained parameterizations. Because the parameterization does not consider contributions from spume drops, the simulated global mass flux (1.5 × 103 Tg y−1) is near the lower end of published estimates. The simulated production of aerosol number (1.4 × 106 m−2 s−1) and OCaer (29 Tg C y−1) fall near the upper end of published estimates and suggest that primary marine aerosols may have greater influences on the physicochemical evolution of the troposphere, radiative transfer and climate, and associated feedbacks on the surface ocean than suggested by previous model studies.

Highlights

Particle production by bursting bubbles at the air-sea interface is the dominant global source of aerosol mass and a major global source of aerosol number (Andreae and Rosenfeld, 2008)
The goals of this study were (1) to formulate a parameterization for primary marine aerosol production based on chemical and physical characteristics of aerosol generated under controlled conditions and the associated physical drivers, (2) to simulate global production fluxes of inorganic sea-salt mass, total particle number, and primary OCaer, and (3) to interpret results in the context of corresponding estimates by other investigators
(1) Simulated mass and number production fluxes based on air entrainment by breaking waves fell within the broad ranges of independent estimates extrapolated from whitecap area on the surface ocean

Summary

Introduction

Particle production by bursting bubbles at the air-sea interface is the dominant global source of aerosol mass and a major global source of aerosol number (Andreae and Rosenfeld, 2008). Organic contents inferred from thermal desorption measurements of aerosols produced artificially from coastal seawater (Modini et al, 2010) and generated naturally from coastal surf (Clarke et al, 2006) suggest lower enrichments. Causes for these differences are not known. Manipulation experiments indicate that the chemical processing of marinederived particulate organic material is a major source of the OH radical and a likely suite of important low molecular weight reaction products including carboxylic acids, ketones, and alcohols (Zhou et al, 2008). Primary marine aerosols scatter incident solar radiation and account for a significant fraction of cloud condensation nuclei (CCN) over the world’s oceans thereby influencing Earth’s radiative balance and climate (Clarke et al, 2006)

Objectives

Results

Conclusion