Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols

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dc.contributor.authorAlroe, Jen_AU
dc.contributor.authorCravigan, LTen_AU
dc.contributor.authorMiljevic, Ben_AU
dc.contributor.authorJohnson, GRen_AU
dc.contributor.authorSelleck, PWen_AU
dc.contributor.authorHumphries, RSen_AU
dc.contributor.authorKeywood, MDen_AU
dc.contributor.authorChambers, SDen_AU
dc.contributor.authorWilliams, AGen_AU
dc.contributor.authorRistovski, ZDen_AU
dc.date.accessioned2024-12-12T21:49:18Zen_AU
dc.date.available2024-12-12T21:49:18Zen_AU
dc.date.issued2020-07-10en_AU
dc.date.statistics2024-12-11en_AU
dc.description.abstractCloud–radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations, and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64∘ S, and accompanied by the highest median cloud condensation nuclei (CCN) concentrations, at 252 cm−3. During the other two episodes, synoptic-scale weather patterns diverted air masses across distances greater than 1000 km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93 % of the total number concentration activating as CCN. Frequent cyclonic weather conditions were observed at high latitudes and the associated strong wind speeds led to predictions of high concentrations of sea spray aerosol. However, these modelled concentrations were not achieved due to increased aerosol scavenging rates from precipitation and convective transport into the free troposphere, which decoupled the air mass from the sea spray flux at the ocean surface. CCN concentrations were more strongly impacted by high concentrations of large-diameter Aitken mode aerosol in air masses which passed over regions of elevated marine biological productivity, potentially contributing up to 56 % of the cloud condensation nuclei concentration. Weather systems were vital for aerosol growth in biologically influenced air masses and in their absence ultrafine aerosol diameters were less than 30 nm. These results demonstrate that air mass meteorological history must be considered when modelling sea spray concentrations and highlight the potential importance of sub-grid-scale variability when modelling atmospheric conditions in the remote Southern Ocean. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.en_AU
dc.identifier.citationAlroe, J., Cravigan, L. T., Miljevic, B., Johnson, G. R., Selleck, P., Humphries, R. S., Keywood, M. D., Chambers, S. D., Williams, A. G., & Ristovski, Z. D. (2020). Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols. Atmospheric Chemistry and Physics., 20(13), 8047-8062. doi:10.5194/acp-20-8047-2020en_AU
dc.identifier.issn1680-7316en_AU
dc.identifier.issn1680-7324en_AU
dc.identifier.issue13en_AU
dc.identifier.journaltitleAtmospheric Chemistry and Physicsen_AU
dc.identifier.pagination8047-8062en_AU
dc.identifier.urihttps://doi.org/10.5194/acp-20-8047-2020en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15814en_AU
dc.identifier.volume20en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherCopernicus Publicationsen_AU
dc.subjectMeteorologyen_AU
dc.subjectAerosolsen_AU
dc.subjectCloudsen_AU
dc.subjectAntarctic Oceanen_AU
dc.subjectClimate modelsen_AU
dc.subjectAustraliaen_AU
dc.subjectAtmosphericsen_AU
dc.subjectNucleien_AU
dc.subjectWeatheren_AU
dc.titleMarine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosolsen_AU
dc.typeJournal Articleen_AU
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