Expedition Antarctica: chasing the clouds

Preben Van Overmeiren replaces filters in a passive sampler © H. Robert – IPF (large view)

Preben Van Overmeiren replaces filters in a passive sampler © H. Robert – IPF

(10-02-2021) PhD student Preben Van Overmeiren collected samples in Antarctica to learn more about clouds, precipitation and atmospheric circulation in the Southern Hemisphere.

Antarctic air samples

Preben Van Overmeiren is a PhD student at the research group Environmental Organic Chemistry and Technology (EnVOC) at Ghent University. He collected organic and inorganic atmospheric particles for the CHASE project, which seeks to learn more about atmospheric circulation in the Southern Hemisphere and how atmospheric particles and gas phase compounds are transported to Antarctica.

"Firstly, we’ve sampled the air in Antarctica to learn details about the chemical characteristics of atmospheric particles and gaseous compounds", the researcher explains.

"Secondly, we’re investigating the atmospheric transport pathways, a task the Royal Meteorological Institute oversees. This year the project is coming to an end, but we’ve still got work to do to analyze the samples we’ve collected." Some of the samples will be analyzed in the EnVOC lab at Ghent University.

Clouds and precipitation

He also did field work for the CLIMB project, which is investigating how such particles influence cloud formation and precipitation in Antarctica.

The project focuses on taking measurements of meteorological, aerosol, cloud, and precipitation characteristics at the Princess Elisabeth Station and directly at the cloud level, on the edge on the Antarctic plateau south of the Sør Rondane Mountains.

"Aerosols are important to the cloud formation process. The IPCC defined the effect of clouds on climate change as one of the biggest uncertainties."

Various primary and secondary aerosols affect the microphysics of clouds. They act as nuclei for the formation of cloud droplets or small ice crystals.

Clouds are an important factor in the earth’s albedo, they are reflecting a fraction of the sun’s radiation back into space but also reflecting back thermal radiation of the earth itself.

Inland vs coastal regionsPreben Van Overmeiren removes a filter from a sampler in Antarctica

Preben collected atmospheric samples along a 250 km transect from the high plateaus to the coast.

"This has helped us compare the transport and composition of aerosols in inland highland regions to their transport and composition in lowland coastal regions."

For example, in the interior highlands, atmospheric circulation transports fine particles produced through mountain erosion. At the coast, atmospheric circulation brings in compounds from different landmasses surrounding Antarctica in the Southern Hemisphere: South America, Africa and Australia.

"At the coast you tend to see more anthropogenic influence showing up in our samples."

Expedition Antarctica: tentChristmas in Antarctica

Due to poor weather conditions, Preben had to change his flight schedule and got to celebrate Christmas and New Year’s in Antarctica at the Princess Elisabeth Antarctica station, together with the crew there.

"This was special! If there ever were one time in your life to spend Christmas and New Year’s in Antarctica, this was the year. COVID-19 has made it impossible to have large gatherings in Belgium. But in Antarctica, as we were all together isolated from the world in a COVID-free environment, it was more enjoyable."

More info

CHASE started in 2017 with funding from the Belgian Federal Science Policy Office (BELSPO). It has four main partners: the Université Libre de Bruxelles (ULB), the Vrije Universiteit Brussels (VUB), Ghent University and the Royal Meteorological Institute of Belgium (KMI/IRM).

CLIMB is coordinated by the Royal Meteorological Institute with partners Ghent University, KU Leuven and the Royal Belgian Institute for Space Aeronomy (IASB-BIRA).