Measurements of Aerosols, Radiation, andClouds over the Southern Ocean
The Southern Ocean is the stormiest place on Earth, buffeted bywinds and waves that circle the ice of Antarctica, sheathed in clouds
that mantle a dynamic ocean with rich ecosystems. The remote andusually pristine environment, typically removed from many aerosol
sources, makes the Southern Ocean unique for examining cloud‐aerosol interactions and particles found in sea spray. Even though
it is remote, the Southern Ocean influences the atmospheric andoceanic circulation of the entire Southern Hemisphere and beyond.
Weather and earth system models are challenged by uncertainties
and biases in the simulation of Southern Ocean clouds, aerosols,and precipitation, and almost universally underestimate sunlightreflected by near-surface clouds. Many of these difficulties trace backto poor physical understanding of the underlying physical processes.
The Measurements of Aerosols, Radiation, and Clouds over theSouthern Ocean (MARCUS) field campaign, conducted by theU.S. Department of Energy’s Atmospheric Radiation Measurement(ARM) user facility, acquired comprehensive observations over theSouthern Ocean from October 2017 until April 2018. To obtainthese measurements, the second ARM Mobile Facility (AMF2) wasdeployed on the Australian Antarctic supply vessel Aurora Australis as
it made routine trips between Hobart, Australia, and Antarctica, andvisited Macquarie Island and Australian Antarctic stations Mawson,
Davis, and Casey.
AUSTRALIA

MacquarieIslandDavis

The MARCUS campaign was part of a large international multi‐agency effort called the Southern Ocean Clouds, Radiation, Aerosol
Transport Experimental Study (SOCRATES). The MARCUS
observations are self‐standing and unique within SOCRATES. Thecampaign captured the variability in aerosol and cloud properties
across the Southern Ocean from spring to autumn, especially incold waters at latitudes poleward of 60˚S, where supercooled andmixed‐phase boundary layer clouds in the cold sector of cyclones are
frequent and where past and planned observations are most sparse.

Science Objectives

HobartMawsonThe Southern Ocean’s remoteness and harsh conditions make it
difficult to study.

Casey

ANTARCTICA

The second ARM Mobile Facility traveled from Hobart, Australia, tothree Antarctic research stations and Macquarie Island via the Southern Ocean. Four five-week research cruises of about 7,000 kilometers
each took place over a six-month period.

MARCUS collected measurements of aerosols in the boundary
layer, retrieving vertical distributions of macrophysical andmicrophysical properties of liquid and mixed‐phase clouds,
and measuring downwelling radiative fluxes over the SouthernOcean. The primary campaign objectives were to:• understand the synoptically varying vertical structure ofSouthern Ocean boundary layer clouds and aerosols• discover the sources and sinks of Southern Ocean cloud
condensation nuclei and ice nucleation particles, including
the role of local biogenic sources over spring, summer,and fall

Atmospheric Radiation Measurement • USER FACILITY• understand the mechanisms controlling supercooled liquidand mixed‐phase clouds• advance retrievals of clouds, precipitation, and aerosols over
the Southern Ocean from ground‐based and satellite remotesensing.

Research Instrumentation
Deployment aboard a moving vessel requires special preparation,
including keeping instruments clean of sea spray and correcting
for the pitch and roll of the ship. Onsite operators monitor andmaintain the mobile facility to make sure the best and mostcomplete data set is obtained.
Measurement Capabilities. They include meteorological andaerosol instrumentation, broadband and spectral radiometer
suites, and remote-sensing instruments.
• Cloud Condensation Nuclei Particle Counter• Nephelometer• Condensation Particle Counter• Ozone Monitor• Surface Meteorological Instrumentation• Cimel Sunphotometer• Balloon-Borne Sounding System – sondes (weather balloons)launched each day at regular intervals• Micropulse Lidar• Microwave Radiometer (MWR) and 3-Channel MWR• Marine W-Band ARM Cloud Radar• Ceilometer

The second ARM Mobile Facility consists of instruments,operations shelters, and data and communications systems
and is well-traveled on the high seas.

Using an ARM Mobile Facility. Mobile facility deployments
are determined through a user proposal process. An AMF canbe deployed for stand-alone campaigns or for collaboration withinteragency experiments. Scientists interested in using an AMF
are encouraged to submit proposals at the following web page:www.arm.gov/research/campaign-proposal.

Collaborations
The ARM Facility is collaborating with the Australian Antarctic
Division and the Australian Bureau of Meteorology on the
MARCUS campaign.

• Inertial Navigation System, known as SeaNav• Sky Radiometers on Stand for Downwelling Radiation

For more information:• Laser Disdrometer

Hanna Goss, ARM Public Information Officer
Pacific Northwest National Laboratory
hanna.goss@pnnl.gov• Total Sky Imager• Marine Atmospheric Emitted Radiance Interferometer• Beam-Steering Radar Wind Profiler.
Data and Communications System. Continuous
measurements obtained by the sensors and instruments arecollected by integrated data systems. These data are checked for
quality and transmitted periodically, when the ship is in port,to the ARM Data Center for storage and availability to thescientific community.

Greg McFarquhar, MARCUS Principal Investigator
University of Oklahoma
mcfarq@ou.edu
Heath Powers, AMF2 Operations LeadLos Alamos National Laboratory
hpowers@lanl.gov

www.arm.gov/research/campaigns/amf2017marcus
DOE/SC-ARM-16-055
Revised October 2018

ARM is funded through the U.S. Department of Energy’s Office of Science.
Additional information is available on the ARM website at www.arm.gov.