Observations of clouds, aerosols, precipitation, and surface radiation over the Southern Ocean: An overview of CAPRICORN, MARCUS, MICRE and SOCRATES

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  • 1 Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, Norman, OK
  • 2 School of Meteorology, University of Oklahoma, Norman, OK
  • 3 Department of Atmospheric Sciences, University of Washington, Seattle, WA
  • 4 Australian Bureau of Meteorology, Melbourne, Australia
  • 5 Australian Antarctic Programme Partnership, Institute for Marine and Antarctic Science, University of Tasmania, Hobart, Australia
  • 6 Department of Atmospheric Science, Colorado State University, Fort Collins, CO
  • 7 Australian Antarctic Division, Hobart, Australia
  • 8 Scripps Institution of Oceanography, La Jolla, CA
  • 9 Centre National de Recherches Météorologiques, UMR3589, Toulouse, France
  • 10 NorthWest Research Associates, Redmond, WA
  • 11 Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO
  • 12 School of Earth, Atmosphere and Environment, Monash University, Melbourne, Australia
  • 13 School of Earth Sciences, University of Melbourne, Melbourne, Australia
  • 14 Department of Atmospheric Sciences, University of Illinois, Urbana, IL
  • 15 National Center for Atmospheric Research, Boulder, CO
  • 16 University of Utah, Salt Lake City, UT
  • 17 Department of Atmospheric Sciences, Pusan National University, Busan, South Korea
  • 18 Karlsruhe Institute of Technology, Karlsruhe, Germany
  • 19 Climate Science Centre, Oceans and Atmosphere, CSIRO, Melbourne, Australia
  • 20 School of Earth and Atmospheric Sciences, Queensland University of Technology, Brisbane, Australia
  • 21 NOAA, Boulder, Colorado
  • 22 Beijing Normal University, Beijing, China
  • 23 Handix Scientific, Boulder, Colorado
  • 24 Peking University, Beijing, China
  • 25 National Institute of Water and Atmospheric Research, Wellington, New Zealand
  • 26 Gateway Antarctica, University of Canterbury, Christchurch, New Zealand
  • 27 School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
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Abstract

Weather and climate models are challenged by uncertainties and biases in simulating Southern Ocean (SO) radiative fluxes that trace to a poor understanding of cloud, aerosol, precipitation and radiative processes, and their interactions. Projects between 2016 and 2018 used in-situ probes, radar, lidar and other instruments to make comprehensive measurements of thermodynamics, surface radiation, cloud, precipitation, aerosol, cloud condensation nuclei (CCN) and ice nucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase cloudsnucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase clouds common to this pristine environment. Data including soundings were collected from the NSF/NCAR G-V aircraft flying north-south gradients south of Tasmania, at Macquarie Island, and on the RV Investigator and RSV Aurora Australis. Synergistically these data characterize boundary layer and free troposphere environmental properties, and represent the most comprehensive data of this type available south of the oceanic polar front, in the cold sector of SO cyclones, and across seasons.

Results show a largely pristine environments with numerous small and few large aerosols above cloud, suggesting new particle formation and limited long-range transport from continents, high variability in CCN and cloud droplet concentrations, and ubiquitous supercooled water in thin, multi-layered clouds, often with small-scale generating cells near cloud top. These observations demonstrate how cloud properties depend on aerosols while highlighting the importance of confirmed low clouds were responsible for radiation biases. The combination of models and observations is examining how aerosols and meteorology couple to control SO water and energy budgets.

Corresponding Author: Greg M. McFarquhar, Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma 120 David L. Boren Blvd., Norman, OK 73072 mcfarq@ou.edu; 405-325-3041

Abstract

Weather and climate models are challenged by uncertainties and biases in simulating Southern Ocean (SO) radiative fluxes that trace to a poor understanding of cloud, aerosol, precipitation and radiative processes, and their interactions. Projects between 2016 and 2018 used in-situ probes, radar, lidar and other instruments to make comprehensive measurements of thermodynamics, surface radiation, cloud, precipitation, aerosol, cloud condensation nuclei (CCN) and ice nucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase cloudsnucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase clouds common to this pristine environment. Data including soundings were collected from the NSF/NCAR G-V aircraft flying north-south gradients south of Tasmania, at Macquarie Island, and on the RV Investigator and RSV Aurora Australis. Synergistically these data characterize boundary layer and free troposphere environmental properties, and represent the most comprehensive data of this type available south of the oceanic polar front, in the cold sector of SO cyclones, and across seasons.

Results show a largely pristine environments with numerous small and few large aerosols above cloud, suggesting new particle formation and limited long-range transport from continents, high variability in CCN and cloud droplet concentrations, and ubiquitous supercooled water in thin, multi-layered clouds, often with small-scale generating cells near cloud top. These observations demonstrate how cloud properties depend on aerosols while highlighting the importance of confirmed low clouds were responsible for radiation biases. The combination of models and observations is examining how aerosols and meteorology couple to control SO water and energy budgets.

Corresponding Author: Greg M. McFarquhar, Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma 120 David L. Boren Blvd., Norman, OK 73072 mcfarq@ou.edu; 405-325-3041
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