Towards an understanding of the thermodynamic structure of the Marine Atmospheric Boundary Layer over the Southern Ocean — Australian Meteorological and Oceanographic Society
  1. Schedule
  2. 16. General atmosphere session
  3. Towards an understanding of the thermodynamic structure of the Marine Atmospheric Boundary Layer over the Southern Ocean

Towards an understanding of the thermodynamic structure of the Marine Atmospheric Boundary Layer over the Southern Ocean (#259)

Son Truong 1 , Yi Huang 2 3 , Francisco Lang 1 , Steven Siems 1 4 , Michael Manton 1
  1. School of Earth, Atmosphere and Environment, Monash University, CLAYTON, Victoria, Australia
  2. The University of Melbourne, Parkvale, VIC, Australia
  3. ARC Centre of Excellence for Climate Extremes, The University of Melbourne, Melbourne, Victoria, Australia
  4. Australian Research Council (ARC) Centre of Excellence for Climate Extremes, Monash University, CLAYTON, Victoria, Australia

The atmospheric boundary layer (ABL) over the Southern Ocean (SO) remains poorly understood due, primarily, to sparse observations in this remote region. This poor understanding directly contributes to the persistent large biases in the atmospheric radiation budget over the SO in both climate models and reanalysis products. Motivated by the need to improve the understanding of key atmospheric processes of the SO climate system, a range of ship- and airborne field campaigns have been taking place in recent years, yielding an unprecedented wealth of measurements ranging from Hobart to the edge of Antarctica.

In this research, 1703 atmospheric high-resolution soundings from several field campaigns including CAPRICORN 2016 & 2018,  SOCRATES (Jan – Feb 2018), MARCUS (Oct 2017 – Apr 2018) are complemented with routine soundings from Macquarie Island (2016-2018) to map out the ABL climatology over the SO. The analysis explores variations in the key ABL characteristics in relation to the sea surface temperature (SST) and synoptic meteorology (e.g. distance to atmospheric fronts / cyclone cores). A simple clustering analysis is also performed to complement the analysis.

The initial results show that the ABL over the SO can be classified into 10 clusters which well represent the various synoptic patterns across the mid- and high-latitude SO. Multi-layer clouds are commonly present over the cold SSTs (SST < 5ºC), accounting for 41% of 864 soundings. No-cloud, deep-cloud and one-layer cloud scenarios are present 15%, 2% and 42% of the time. Over warmer SSTs (SST > 5ºC), multi-layer clouds account for 31% of 839 soundings, while no-layer, all-layer and one-layer clouds are recorded14%, 2%, 53% of the time. The multi-layer clouds are commonly associated with either secondary above or below inversion over the cold SSTs, but more frequently linked to the secondary below inversion over the warm SSTs.

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