Sea2Cloud: From Biogenic Emission Fluxes to Cloud Properties in the Southwest Pacific
Résumé
The goal of the Sea2Cloud project is to study the interplay between surface ocean
biogeochemical and physical properties, fluxes to the atmosphere and ultimately their impact
on cloud formation under minimal direct anthropogenic influence. Here we present an
interdisciplinary approach, combining atmospheric physics and chemistry with marine
biogeochemistry, during a voyage between 41 and 47°S in March 2020. In parallel to ambient
measurements of atmospheric composition and seawater biogeochemical properties, we
describe semi-controlled experiments to characterize nascent sea spray properties and
nucleation from gas-phase biogenic emissions. The experimental framework for studying the
impact of the predicted evolution of ozone concentration in the Southern Hemisphere is also
detailed. After describing the experimental strategy, we present the oceanic and meteorological
context including provisional results on atmospheric thermodynamics, composition, and flux
measurements. In situ measurements and flux studies were carried out on different biological
communities by sampling surface seawater from subantarctic, subtropical and frontal water
masses. Air-Sea-Tanks (ASIT) were used to quantify biogenic emissions of trace gases under
realistic environmental conditions, with nucleation observed in association with biogenic
seawater emissions. Sea spray continuously generated produced sea spray fluxes of 34% of
organic matter by mass, of which 4% particles had fluorescent properties, and which size
distribution ressembled the one found in clean sectors of the Southern Ocean. The goal of
Sea2Cloud is to generate realistic parameterizations of emission flux dependences of trace
gases and nucleation precursors, sea spray, cloud condensation nuclei and ice nuclei using
seawater biogeochemistry, for implementation in regional atmospheric models
Domaines
MétéorologieOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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