Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties Journal Article uri icon

Overview

abstract

  • Controls on pristine aerosol over the Southern Ocean (SO) are critical; for constraining the strength of global aerosol indirect forcing.; Observations of summertime SO clouds and aerosols in synoptically varied; conditions during the 2018 SOCRATES aircraft campaign reveal novel; mechanisms influencing pristine aerosol-cloud interactions. The SO free; troposphere (3-6 km) is characterized by widespread, frequent new; particle formation events contributing to much larger concentrations (≥; 1000 mg-1) of condensation nuclei (diameters > 0.01 μm); than in typical sub-tropical regions. Synoptic-scale uplift in warm; conveyor belts and sub-polar vortices lifts marine biogenic; sulfur-containing gases to free-tropospheric environments favorable for; generating Aitken-mode aerosol particles (0.01-0.1 μm).; Free-tropospheric Aitken particles subside into the boundary layer,; where they grow in size to dominate the sulfur-based cloud condensation; nuclei (CCN) driving SO cloud droplet number concentrations (Nd; ~ 60-100 cm-3). Evidence is presented for a hypothesized; Aitken-buffering mechanism which maintains persistently high summertime; SO Nd against precipitation removal through CCN replenishment from; activation and growth of boundary layer Aitken particles. Nudged; hindcasts from the Community Atmosphere Model (CAM6) are found to; underpredict Aitken and accumulation mode aerosols and Nd, impacting; summertime cloud brightness and aerosol-cloud interactions and; indicating incomplete representations of aerosol mechanisms associated; with ocean biology.

publication date

  • March 13, 2021

has restriction

  • bronze

Date in CU Experts

  • March 19, 2021 4:25 AM

Full Author List

  • McCoy IL; Bretherton CS; Wood R; Twohy CH; Gettelman A; Bardeen C; Toohey DW

author count

  • 7

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