Aiden Robert Max Jönsson Post doc

Current research

I am currently working on the CleanCloud project as a postdoctoral researcher at the Department of Environmental Science, Atmospheric Unit (ACESL). The project aims to look at how the Earth system will interact with clouds via aerosols in a future with reduced human influence from aerosol emissions.

In 2024-2025, I took part in the CleanCloud Helmos Orographic Cloud Experiment (CHOPIN) campaign at Mt. Helmos, Greece. We brought a ground-based counterflow virtual impactor (CVI) that allows us to sample cloud droplets and ice crystals, dry them, and see what aerosols were activated or scavenged by the cloud. By placing instruments behind this special inlet, we could look at these particles' properties. Now, I am focusing on analyzing the observations of bioaerosols at CHOPIN using fluorescence spectroscopy, and their relations to measurements of ice nucleating particles.

In 2025, I took part in the CleanCloud PIANO campaign at Aarhus University, where sea spray aerosol generation was simulated with seawater samples from the Mediterranean and Arctic. These aerosols were put in a chamber and subjected to processes simulating atmospheric aging by oxidation and exposure to UV light, giving us insights into processes important to their interactions with clouds, such as their hygroscopicity and ice nucleating ability.

As a part of CleanCloud, I am also looking at aerosol-cloud observations taken in the Arctic during the sea ice melt season (on the ARTofMELT campaign).

Prior research

During Ph.D. studies I focused on the curious feature that is the near-exact symmetry in albedo between Earth's Northern and Southern Hemispheres (NH and SH). This feature is surprising since the two hemispheres have very different features, with the NH having much higher clear-sky albedo due to higher aerosol concentrations and more bright land surface area. I investigated how clouds compensate for this clear-sky albedo asymmetry, which may help us understand factors affecting global cloud cover and its features. This investigation was mainly through satellite observations of Earth's radiation balance, output from climate models, and atmospheric simulations.

Previously, I worked with social scientists to calculate exposure to natural hazards (floods, droughts, storms, and temperature extremes) to test whether hazard severity determines humanitarian relief/aid allocation. While the Earth system components I am motivated to study are ultimately very relevant to society, taking part in directly studying environmental impacts on society was an exciting practice.

My master's degree project focused on the role of moisture transport into the Antarctic sea ice zone, and the connection between moisture transport and states of low sea ice extent using satellite observations and atmospheric reanalyses. Antarctica and the Southern Ocean remains really interesting to me, and I hope to continue studying this intriguing region in future studies.