Processes controlling the physical properties of marine boundary layer aerosol particles during ACE 1

Abstract

The goal of the International Global Atmospheric Chemistry (IGAC) Program's first aerosol characterization experiment (ACE-l) was to determine and understand the properties and controlling factors of the aerosol in the remote marine atmosphere, which are relevant to radiative forcing and climate. A key question in terms of this goal and the overall biogeochemical sulfur cycle is what controls the formation, growth, and evolution of particles in the marine boundary layer. Nonsea salt (nss) sulfate aerosol particles in the remote marine atmosphere are thought to have only one primary gaseous precursor, dimethylsulfide (DMS). It is not clear, however, if the flux of DMS from the ocean to the atmosphere is sufficient to account for the total mass of nss sulfate aerosol, and if particle production occurs primarily in the marine boundary layer or the free troposphere. To address these questions, simultaneous measurements of DMS, the aerosol chemical mass size distribution, and the aerosol number size distribution from 3–10,000 nm diameter were made on the NOAA ship Discoverer during ACE-1. The data reveal that particle formation occurs in the free troposphere on large spatial and vertical scales and is not confined to regions of precursor gas emissions.