How do aerosols help our atmosphere clean itself?

They say “By shading and cooling the Earth’s surface, cloud cover plays a direct role in rates of global climate change”, but that’s only half the story. Cloud cover at night, i.e. the other 50% of the year, has the opposite effect and slows the rate of heat loss.

Everyday our atmosphere has to find a way to clean itself of the air, sea and soil pollution we throw at it, says Phys.org.

So, in order to study how this cleaning process works, the University of Melbourne’s Dr. Robyn Schofield is sailing through the pristine environment of the Southern Ocean to our most untouched continent, Antarctica—an environment with the least amount of pollution on the planet.

But a detailed study in this part of the world isn’t feasible without a fully functioning laboratory. So, onboard the ship with Dr. Schofield is a unique, mobile, air chemistry, shipping-container laboratory, known as AIRBOX or the Atmospheric Integrated Research Facility for Boundaries and Oxidative Experiments.

This custom-built laboratory is small—only 2.5 by 2.5 by 3 metres. But within that space it has nine instruments designed to carry out comprehensive atmospheric monitoring—taking measurements in the most remote places.

For this trip, the research team have also added another eight guest instruments measuring atmospheric chemistry, gases and aerosols over the Southern Ocean.

AIRBOX, an unsubtle stowaway, will travel on the icebreaker RSV Aurora Australis on four voyages this summer, as part of the Australian Antarctic Program.

With two expeditions on each of the voyages, Dr. Schofield and her colleagues will measure the summer season while all the Antarctic stations are resupplied.

And there’s a roster of expertise heading south throughout the Southern Hemisphere’s summer.
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One of the areas the research they are focusing on is clouds.

A CLOUD’S LIFECYCLE

The generation of clouds, starting from an aerosol and ending with rainfall, is an important part of our atmosphere’s self-cleaning. However, researchers want to know more about the process and understand how best to keep the system working in our warming climate.

“Clouds are very important, as well as beautiful weather phenomena,” Dr. Schofield says.

“By shading and cooling the Earth’s surface, cloud cover plays a direct role in rates of global climate change”, explains Dr. Schofield, based at the University of Melbourne’s School of Earth Sciences and an associate investigator of ARC Centre of Excellence for Climate Extremes.

Clouds are ‘seeded’ by tiny particles in the air called aerosols. These particles can include dust, soot and salt, some of which are particularly important for supplying nutrients to the oceans.

Water vapour attaches itself to the aerosol particles, condensing into a cloud droplet that is held aloft by air circulation and then grows to form a cloud, then once it gets big enough it will rain out. And the cycle starts again.

Low, shallow clouds are mostly made of water droplets of various sizes. Thin, upper level clouds or cirrus clouds are made of tiny ice particles. And deep thunderstorm clouds can contain both liquid and ice in the form of cloud and raindrops, cloud ice, snow and hail.

“The concentrations of aerosols in the Southern ocean and Antarctic atmosphere differs from anywhere else on Earth. Their measurement is of great interest to the international climate-modelling community and for the Australian climate more generally,” Dr. Schofield says.

CLOUDS AND THE CLIMATE

The AIRBOX project aims to better understand where the aerosols are coming from that are influencing the clouds and how they are made.

Full report here.