ACPD Atmospheric Chemistry and Physics Discussions ACPD Atmos. Chem. Phys. Discuss. 1680-7375 Göttingen, Germany 10.5194/acp-2022-104 Measurement Report: Real-Time Remote Sensing of the Coastal Boundary Layer and its Interaction with Meteorology at Cape Grim, Australia Chen Zhenyi 1 Schofield Robyn https://orcid.org/0000-0002-4230-717X 2 Keywood Melita https://orcid.org/0000-0001-9953-6806 3 Cleland Sam 4 Williams Alastair G. https://orcid.org/0000-0002-0568-8487 5 Griffiths Alan https://orcid.org/0000-0003-1135-1810 5 Wilson Stephen https://orcid.org/0000-0003-4546-2527 6 Rayner Peter https://orcid.org/0000-0001-7707-6298 2 Shu Xiaowen 7 School of Ecology and Environment, Beijing Technology and Business University, 100048, Beijing, China School of Earth Sciences, University of Melbourne, 3010, Melbourne, VIC, Australia Climate Science Centre, Oceans and Atmosphere, CSIRO, 3195, Aspendale, VIC, Australia Observing Systems and Operations, Bureau of Meteorology, 7330, Smithton, Tasmania, Australia Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia School of Earth, Atmosphere and Life Sciences, University of Wollongong, 2522, NSW, Australia Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, 230031, Hefei, China 09 03 2022 2022 1 21 Copyright: © 2022 Zhenyi Chen et al. 2022 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://acp.copernicus.org/preprints/acp-2022-104/ The full text article is available as a PDF file from https://acp.copernicus.org/preprints/acp-2022-104/acp-2022-104.pdf

<p>Despite considerable efforts during the last decade, real-time characterization of the marine boundary layer and aerosol optical properties over the Southern Ocean remains scarce. We conducted simultaneous measurements of the marine boundary layer utilizing a synergy of remote sensing technology at the Baseline Air Pollution Station at Cape Grim in northwestern Tasmania, Australia, from 14 May to 16 July 2019. Aerosol optical properties were monitored by lidar (miniMPL) and a ceilometer to identify the boundary layer height, and sodar provided wind profiles to investigate their influences on the layer evolution. Boundary layer heights simulated using the Weather Research and Forecasting (WRF) model were also employed for comparison purposes. Through complementary analyses of three cases representing different source influences (marine, sea breeze and continental), this paper evaluates two algorithms (Image Edge Detection Algorithm (IEDA) and gradient method) for boundary layer height detection and examines the vertical aerosol distribution within the boundary layer at Cape Grim with an emphasis on the contributions of regional and local meteorology. We found IEDA generally performed better than the gradient method, especially during the marine-flow-influenced period with a convective layer structure. Different features of boundary layer structures in three episodes, including differential boundary layer growth and interaction with wind evolutionary processes were investigated. One was characterized by a diurnal variation with a boundary layer height of approximately 0.2&ndash;0.5 km, associated with the veering of the wind vector within the marine boundary layer during the development of a sea breeze. The other showed a thermally stable layer below 0.3 km with an enhanced extinction coefficient and linear depolarization ratio under the influence of continental sources, which was also validated by the observation from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The increasing extinction coefficient and depolarization ratio with wind speeds may be attributed to the increased wet sea salt production and regional transportation from mainland Australia.</p>