ICE-ACCACIA is a project which will be running alongside the main ACCACIA project. It will collect samples which will be used to investigate the properties of the aerosols with respect to their properties as ice nuclei. From the samples we will be able to quantify the number and efficiency of ice nuclei in the remote Arctic for the first time. The exact chemical composition of these particles is very important when it comes to how good they are at ‘seeding ice crystals’.
This sensitivity of clouds to ice nucleation arises in part because cloud water droplets in the absence of particles which nucleate ice can supercool to about -36oC. In fact very pure water will remain liquid at temperatures well below 0 oC but will freeze instantly when the ‘supercooled’ liquid water comes into contact with dust (checkout this YouTube clip).
Samples collected in Kiruna will be analysed in a laboratory which has been set up in the Arena Arctica hangar. The samples are suspended in tiny cloud droplets, and the temperatures at which they freeze are recorded by taking a video of the droplets as they are cooled.
The ICE-ACCACIA project is led by Dr Ben Murray from the Institute for Climate and Atmospheric Science in Leeds, the ICE-ACCACIA team includes Dr Jim McQuaid, Dr Kelly Baustian and Dr Theo Wilson from ICAS. The results are used in atmospheric models which give us a better understanding of the effects of cloud on climate.