Aerosol, Clouds and the Southern Ocean From Cape Grim to the RV - - PowerPoint PPT Presentation

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Aerosol, Clouds and the Southern Ocean From Cape Grim to the RV - - PowerPoint PPT Presentation

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Aerosol, Clouds and the Southern Ocean From Cape Grim to the RV Investigator Melita Keywood and Alain Protat 20 May 2015 OCEANS AND ATMOSPHERE FLAGSHIP Poor simulation of Southern Ocean Clouds cloud over SO Satellite obs >0.8 in a band

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Aerosol, Clouds and the Southern Ocean

From Cape Grim to the RV Investigator

OCEANS AND ATMOSPHERE FLAGSHIP

Melita Keywood and Alain Protat 20 May 2015

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  • cloud over SO

>0.8 in a band between 40° and 60°S

  • reanalysis

underestimates cloud cover by about 0.1-0.2

Naud et al., 2014

Poor simulation of Southern Ocean Clouds

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Wood et al., (

Satellite obs Reanalysis products

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Photo from Dagmar 3 |

What’s so important about the atmosphere over the Southern Ocean?

Two main cloud regimes affecting the shortwave radiation in the SO 1) frontal clouds because they are highly reflective 2) low-level clouds because they are ubiquitous (Haynes et al. 2011) Large radiation bias for Southern Ocean (models

  • verestimate radiation) e.g.

Trenberth and Fasullo (2010)

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Southern Ocean- modern surrogate for pre- industrial aerosol conditions

  • aerosol forcing

associated with ACI

  • ver the SO is small

relative to NH

Adapted from Kooperman et al. (2012) 4 |

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SOCRATES Whilte Paper 2014

Cape Grim

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The processes that influence cloud-forming aerosol properties in the remote marine atmosphere such as the SO are poorly understood (Quinn and Bates 2011)

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DMS only important in summer

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RV Investigator

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Maiden Science Voyage INV2015-v01

  • Piggy backed onto

Moorings voyage

  • 21-29 March 2015

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Baseline sector- 22-28

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Relationship to Cape Grim

  • Ship was in Baseline sector

22-28 March

  • Back trajectories (96 hours)

carried out every 6 hours

  • 5 cases of back trajectory

passing through location of ship (approx.)

  • 18 hours behind
  • 23 March (no CN data)
  • 26 March (CCN and CN

data)

  • CPC colocation at Cape

Grim agreed within 1%

  • CCN colocation at Cape

Grim agreed within 20%

CCN 190 CN 260 CCN 82 CN 400

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Photo by Dougie 11 |

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Periodical features

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Diurnal features

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Different patterns

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Presentation title | Presenter name 15 |

From Alain Protat and Eric Schulz

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Summary of quick look at data

  • Remove smoke plume
  • CN concentrations between 100-800 particles cm-3
  • CCN concentrations 20-200 particles cm-3
  • CN decreases from SO to Cape Grim; CCN increases
  • 5 day cycle CN and DMS (clearer in 2nd half of journey when data

set is more complete

  • CCN/CCN ratio increases on 26th from 20% to 80% and remains at

80%- after this we see a clear diurnal cycle in CN, CCN, SO4 but not DMS

  • Increase in CCN/CN followed by presence of low level clouds (less

than 1km)

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What next?

More voyages on RV Investigator (for instruments and others) CAPRICORN- Clouds, Aerosols, Precipitation, Radiation, and atmospheric Composition Over the southeRn oceaN –led by Alain Protat- March 2016 ACRE -Antarctic Cloud and Radiation Experiment led by Simon Alexander (AAD)- Macquarie Island 2016 SOCRATES- proposal- US led-SO Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) CSIRO OCE Post Doc – being advertised now! See CSIRO Careers web site http://csiro.nga.net.au/?jati=252ba9a8-bac7-16df-b7c4- 88cea809bb90

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Acknowledgements

  • Alain Protat (BoM)
  • Jason Ward, James Harnwell, Suzie Molloy, Marcel van der Schoot, Paul

Selleck, Sarah Lawson, Ian Galbally CSIRO

  • Zoran Ristovski, Luke Cravigan, Joel , Branka QUT
  • Dave Griffith and Dagmar UoW
  • Robyn Schofield, Dougie, Stephani Uni Melbourne
  • Grant Edwards Macquarie Uni
  • MNF Operations particularly Max Maguire and Lisa Woodward
  • Ian McRobert, Will Ponsonby, Steve Thomas, Brett Muir CSIRO
  • Leigh Roberts CSIRO
  • Crew
  • MNF TAG
  • O&A CDF and MNF for providing operating
  • Ken Glasson (BoM), Tom Trull (Voyage Leader), Eric Shultz (BoM)

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Photos by Stewart Wilde

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Photo from Dagmar 39 |