Marine boundary layer sea spray aerosol number concentrations during VOCALS-REx
Abstract
Marine boundary layer (MBL) sea spray aerosols include all the inorganic material (sea-salt), organic matter from biogenic activity (plankton, bacteria, microalgae) and other surface active material (exopolymer) found at the surface ocean. SSA are released into the MBL by bursting air bubbles originating from wind-induced breaking waves at the ocean surface. SSA play a major role in the Earth's radiative budget due to their ability to significantly scatter the solar radiation and because of their high hygroscopicity SSA are effective as cloud condensation nuclei (CCN), thereby influencing cloud droplet numbers. Early studies generally focused on sizes larger than about 0.2μm due to their influence on atmospheric light propagation and also because of the instrumental difficulty to distinguish SSA from the more numerous natural sulfate and fine anthropogenic aerosol. During the last two decades, evidence from laboratory and field experiments showed the existence of SSA aerosol down to 0.01μm . Even though ultrafine SSA (<0.1μm) issue from bubble bursting processes appear present in the MBL, it is still largely unclear that sizes smaller than 0.1μm dominate the number size distribution. In this study, we focus on the SSA and especially the those in the ultrafine fraction of the size distribution that dominate CCN at low supersaturations characteristic of stratus clouds near 0.3%. We analyze thermally resolved airborne aerosol measurements made in the MBL during the VAMOS Ocean-Cloud-Atmosphere-Land-Study Regional Experiment (VOCALS-REx) over the the Southeast Pacific. We confirm that open-ocean SSA effective as CCN are produced from bubble bursting processes are present at dry sizes as small as 0.040μm.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.A51D0085B
- Keywords:
-
- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 3311 ATMOSPHERIC PROCESSES / Clouds and aerosols