Research findings revealed a crucial role of biological particles, including pollen, spores, and bacteria, in the formation of ice within Arctic clouds, Stockholm University’s press office reports.
Research on the connection between biological particles and the formation of ice in Arctic clouds was conducted at the Zeppelin Observatory, which is situated in Svalbard. Findings were published in Nature Communications journal.
This research offers critical insights into the origin and properties of biological and ice nucleating particles in the Arctic that could enable climate model developers to improve the representation of aerosol-cloud interactions in models and reduce uncertainties related to anthropogenic radiative forcing estimates, Paul Zieger, Associate Professor at Stockholm University and co-author, stated.
The observations were carried out for four years in Svalbard. Scientists set up special traps at an altitude of almost 500 meters above sea level. They captured aerosol droplets and condensation nuclei. The researchers periodically extracted these solid particles and studied their quantity, structure and composition.
We have individually identified and counted these biological particles using a sensitive optical technique reliant on light scattering and UV-induced fluorescence. This precision is essential as we navigate through the challenge of detecting these particles in minuscule concentrations, akin to finding a needle in a haystack, Gabriel Freitas, lead author and PhD student at Stockholm University, detailed their innovative approach.
According to the researchers, aerosol particles of organic origin had a particularly strong influence on cloud formation in the Arctic during the summer and spring months. More than 90% of the particles that initiated ice crystal formation at high temperatures (-12 °C to -15 °C) in summer were of biological origin. The corresponding proportion in winter was still high, from 50% to 85%.
The scientists used different methodologies, including electron microscopy and the detection of specific substances, such as the sugar alcohol compounds arabitol and mannitol, to confirm the presence of biological particles.
While arabitol and mannitol are present in various microorganisms, their presence in the air are related to fungal spores, and might originate both from local sources or from long range atmospheric transport, Karl Espen Yttri, senior scientist at the Climate and Environmental Research Institute NILU and a co-author of the study, said.
The results provide evidence that biological particles dominate the concentration of ice crystal-forming particles at high temperatures in the Arctic. This indicates an important role of the biosphere in the formation of ice in Arctic clouds.
Studying the relationship between the concentration of organic compounds in the air and cloud formation can help predict how the region's climate will change in the future, the authors stated.
The editorial board of The Arctic Century