Atmospheric scientists will use ships, aircraft and satellites to study super-cooled Southern Ocean clouds this summer. The project involving Australian and United States researchers will gather data on super-cooled cloud formations, which are clouds that remain as liquid water well below freezing.

Clouds consist of water that normally would freeze to ice crystals. In super-cooled clouds, the water remains in a liquid state and thus, the clouds have different properties and behaviors. Picture: Michael Wenger
Clouds consist of water that normally would freeze to ice crystals. In super-cooled clouds, the water remains in a liquid state and thus, the clouds have different properties and behaviors. Picture: Michael Wenger

Australian Antarctic Division atmospheric scientist, Dr Simon Alexander, said while these clouds occur frequently above the Southern Ocean and around coastal Antarctica, little is known about them. “We are going to look at the composition of clouds, how much ice or water they contain, and determine how they affect the weather and climate of the region,” Dr Alexander said. From October through to March Australia’s icebreaker Aurora Australis, the CSIRO’s RV Investigator and the US National Science Foundation’s Gulfstream V aircraft, managed by the National Center for Atmospheric Research, will gather information on the clouds on many trips south from Hobart.

A balloon filling station (green object on left), a cloud radar (centre) and wind profiling radar (right) on the Aurora Australis. Credit: © Phil Boxall, AAD
A balloon filling station (green object on left), a cloud radar (centre) and wind profiling radar (right) on the Aurora Australis. Credit: © Phil Boxall, AAD

The Aurora Australis has had more than seven tonnes of equipment attached to a specially strengthened deck, including 24 atmospheric instruments from the US Department of Energy’s Atmospheric Radiation Measurement (ARM) Mobile Facility. ARM Mobile Facilities Operations Manager, Kim Nitschke, said the scientists on the ship will monitor the clouds and the aerosols which contribute to cloud formation. “A cloud lidar will use laser pulses to measure the thickness, composition and height of the clouds, while a cloud radar and microwave radiometer will look at the liquid and ice content,” Mr Nitschke said. “Weather balloons will also be launched every six hours to measure temperature, winds and humidity above the ocean.” Similar instruments will be carried by the RV Investigator across ice-free areas of the Southern Ocean in early 2018.

The NSF/NCAR Gulfstream V aircraft is a cutting-edge observational platform that will use on-board instrumentation to study mixed-phase clouds (ice and water) and super-cooled liquid clouds over the Southern Ocean this summer. Credit: ©UCAR, licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, via OpenSky.
The NSF/NCAR Gulfstream V aircraft is a cutting-edge observational platform that will use on-board instrumentation to study mixed-phase clouds (ice and water) and super-cooled liquid clouds over the Southern Ocean this summer. Credit: ©UCAR, licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, via OpenSky.

In the air, a United States research aircraft will collect information on the thermodynamic and physical properties above, below and within clouds. “It may be an interesting ride, as the plane will fly ramped ascents and descents through aerosols, storms, and some super-cooled water clouds,” Dr Alexander said. “There will be about 16 flights between mid-January and late February and some of these flights will occur at the same time that the ships are traversing the ocean.” The research will feed into climate models to improve global weather and climate forecasts in the high southern latitudes and across the globe.

Source: Australian Antarctic Division