The potential of Icelandic dust to affect the Arctic clouds

 Icelandic dust makes ice in clouds

Dust particles can change the radiative properties of cold clouds via reducing their liquid water content and albedo. New study of Sanchez-Marroquin et al. (2020) shows that Icelandic volcanic dust generated by glacio-fluvial processes is an active Ice-Nucleating Particle (INP) similarly to Low Latitude Dust (LLD), but contrarily to freshly deposited volcanic ash. Airborne Icelandic dust sampled from the aircraft is more active INP than LLD at temperatures above −17°C. The greatest contribution of Icelandic dust to the INP population occurs during the summer over large areas of the North Atlantic and the Arctic at altitudes between 3-5.5 km, where mixed-phased clouds are known to occur. In future, increased INP concentrations would lead to a reduction in supercooled water and a decrease in shortwave reflectivity of clouds to produce a positive climate feedback, which has not yet been considered in climate simulations.

Íslenskt ryk og ský

Rykagnir auka myndun ískristalla og þar með skýjamyndun.  Þau hafa hafa áhrif á endurkast sólarljóss og auka á gróðurhúsaáhrif.  Ný rannsókn Sanchez-Marroquin o.fl. (2020) sýnir að basískar rykagnir frá Íslandi, sem eiga yfirleitt uppruna í jökulvatni, eru afar virkar í myndun ískristalla, virkari en ryk frá eyðimörkun sunnar á hnettinum.  Sýni sem tekin voru úr flugvél sýndu að ryk frá landinu eykur á skýjamyndun á víðfeðmum svæðum yfir Norður-Atlandshafi og heimskautasvæðunum í 3-5,5 km hæð.  Aukin rykmengun getur minnkað vernd gegn orkumiklum sólargeislum og aukið á hlýnun jarðar, sem mikilvægt er að taka tillit til við gerð loftslagslíkana.

Complete study is available here:
A. Sanchez-Marroquin, O. Arnalds, K. J. Baustian-Dorsi, J. Browse, P. Dagsson-Waldhauserova, A. D. Harrison, E. C. Maters, K. J. Pringle, J. Vergara-Temprado, I. T. Burke, J. B. McQuaid, K. S. Carslaw, B. J. Murray, Iceland is an episodic source of atmospheric ice-nucleating particles relevant for mixed-phase clouds. Science Advances 6, eaba8137 (2020).