Workshop on the Clouds, Workshop on the Clouds, Precipitation and Meteorology Precipitation and Meteorology

over the Southern Oceanover the Southern Ocean

Christian JakobChristian JakobAlain ProtatAlain ProtatSteve SiemsSteve Siems

Tuesday 27 November 2012Tuesday 27 November 2012

Revision of Southern Ocean Revision of Southern Ocean CloudsClouds

Model & Analysis EvaluationModel & Analysis Evaluation• Trenberth & Fasullo (2010) J ClimTrenberth & Fasullo (2010) J Clim

Recent Satellite ClimatologiesRecent Satellite Climatologies• Mace (2010) JGRMace (2010) JGR• Hu et al (2010) JGR Hu et al (2010) JGR • Mace et al (2007) GRLMace et al (2007) GRL• Bennartz (2007) JGRBennartz (2007) JGR

Aerosol Characterization Aerosol Characterization ExperimentExperiment

ACE-1 (1995)ACE-1 (1995)• Russell et al (1998) JGRRussell et al (1998) JGR• Boers et al (1998) JGRBoers et al (1998) JGR• Bates et al(1998) JGRBates et al(1998) JGR

Southern Ocean Cloud ExperimentsSouthern Ocean Cloud ExperimentsSOCEX I & II (1993 & 1995) SOCEX I & II (1993 & 1995)

• Boers et al (1996 & 1998) JGRBoers et al (1996 & 1998) JGR• Jensen et al (2000) ARJensen et al (2000) AR• Yum & Hudson (2004) AEYum & Hudson (2004) AE

Various CSIRO flightsVarious CSIRO flights• Twomey & Warner (1967) JASTwomey & Warner (1967) JAS• Mossop et al (1970) JAMMossop et al (1970) JAM• Paltridge (1976) JGRPaltridge (1976) JGR• Platt (1976) QJRMSPlatt (1976) QJRMS• Stephens (1978) JASStephens (1978) JAS

Revision of Southern Ocean Revision of Southern Ocean CloudsClouds

Q: What makes the meteorology & clouds over the Q: What makes the meteorology & clouds over the Southern Ocean unique compared to the Northern Southern Ocean unique compared to the Northern Hemisphere?Hemisphere?

A:A: The absence of land at the surface.The absence of land at the surface.Absence of terrestrial aerosols (dust)Absence of terrestrial aerosols (dust)

Absence of anthropogenic aerosolsAbsence of anthropogenic aerosols

Q: Are SO clouds & precipitation fundamentally different due Q: Are SO clouds & precipitation fundamentally different due to the microphysics? to the microphysics?

Absence of a no-slip boundary leading to stronger surface winds, Absence of a no-slip boundary leading to stronger surface winds, waves and sea spray waves and sea spray

Q: Is Monin-Obukhov similarity theory even valid?Q: Is Monin-Obukhov similarity theory even valid?

Q: Do we understand cloud & precipitation processes in the Q: Do we understand cloud & precipitation processes in the SO boundary layer? SO boundary layer?

The air is The air is pristine. pristine.

Yum and Hudson (2004 Yum and Hudson (2004 Atmospheric Atmospheric Environment) looked Environment) looked at CCN concentrations at CCN concentrations from various field from various field experiments. experiments.

The lowest concentrations The lowest concentrations of CCN observed was of CCN observed was during SOCEX-1 during SOCEX-1 (winter) off the coast (winter) off the coast of Tasmania.of Tasmania.

There is a lot of wind, There is a lot of wind, wind shear, waves and wind shear, waves and sea spray.sea spray.

During ACE-1, Russell et al looked at During ACE-1, Russell et al looked at the mixing between the boundary the mixing between the boundary layer (400-700 m) and a thick layer (400-700 m) and a thick buffer layer (~1000 m) buffer layer (~1000 m) immediately above the boundary immediately above the boundary layer. Intermittent turbulence was layer. Intermittent turbulence was evident in this buffer layer with evident in this buffer layer with fluxes from both above and below. fluxes from both above and below.

Jensen et al (2000) found wind shear at Jensen et al (2000) found wind shear at the cloud tops during SOCEX. the cloud tops during SOCEX.

Objectives for the DayObjectives for the DayThe immediate aims of this workshop are to:The immediate aims of this workshop are to:

identify the research interests in studying these identify the research interests in studying these weather systems and their associated cloud and weather systems and their associated cloud and precipitation patterns, precipitation patterns,

What are the outstanding scientific questions? What are the outstanding scientific questions? discuss how best to utilise the future observations of discuss how best to utilise the future observations of

the RV Investigator and Cape Grim and facilitate the RV Investigator and Cape Grim and facilitate wider collaboration. wider collaboration.

What are the opportunities? What are the opportunities?

Further aims are to focus and present these research Further aims are to focus and present these research challenges and opportunities to the wider scientific challenges and opportunities to the wider scientific community community in an effort to eventually design the in an effort to eventually design the scientific objectives of an international field campaign.scientific objectives of an international field campaign.

Why/whereWhy/where/when/when is the radiative budget off over the Southern is the radiative budget off over the Southern Ocean? Ocean?

What are the inconsistencies between the simulated and observed What are the inconsistencies between the simulated and observed cloud fields?cloud fields?

What are the dominant cloud regimes, and what are their properties? What are the dominant cloud regimes, and what are their properties?

Are the cloud microphysical properties of SO clouds unique relative Are the cloud microphysical properties of SO clouds unique relative to the NH? to the NH?

Is the atmospheric boundary layer over the SO unique due to winds, Is the atmospheric boundary layer over the SO unique due to winds, waves & sea spray? waves & sea spray?

Is sea spray being overlooked? Wind shear?Is sea spray being overlooked? Wind shear?

What are the inconsistencies between the simulated and observed What are the inconsistencies between the simulated and observed surface fluxes?surface fluxes?

How well are we modeling fronts & precipitation given the sparse How well are we modeling fronts & precipitation given the sparse observations? observations?

What is the meteorology of the different cloud regimes?What is the meteorology of the different cloud regimes?

What are the inconsistencies between the simulated and observed What are the inconsistencies between the simulated and observed cold fronts?cold fronts?

What are the observational challenges in this region?What are the observational challenges in this region?