Impact of wildfire smoke on Arctic cirrus formation, part 1: analysis of MOSAiC 2019–2020 observations

• Main Authors: Ansmann, Albert, Jimenez, Cristofer, Roschke, Johanna, Bühl, Johannes, Ohneiser, Kevin, Engelmann, Ronny, Radenz, Martin, Griesche, Hannes, Hofer, Julian, Althausen, Dietrich, Knopf, Daniel A., Dahlke, Sandro, Gaudek, Tom, Seifert, Patric, Wandinger, Ulla
• Format: Text
• Language: English
• Published: 2024
• Subjects: Arctic; Breaker
• Online Access: https://doi.org/10.5194/egusphere-2024-2008; https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2008/

The number of wildfire smoke layers in the upper troposphere per fire season increased at mid and high northern latitudes during the last years. To consider smoke in weather and climate models appropriately, the influence of smoke on a variety of atmospheric processes needs to be explored in detail. In this study, we focus on the potential impact of wildfire smoke on cirrus formation. For the first time, state-of-the-art aerosol and cirrus observations with lidar and radar, presented in part 1 of a series of two articles, are closely linked to comprehensive modeling of gravity-wave-induced ice nucleation in cirrus evolution processes, presented in part 2. The complex study is based on aerosol and ice cloud observations in the central Arctic during the one-year MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) expedition. For almost a year (from the summer of 2019 to the spring of 2020), aged Siberian wildfire smoke polluted the tropopause region over the central Arctic and many cirrus systems developed in the polluted upper troposphere. Goal of the data analysis (part 1) is to provide observational evidence for a dominating impact of aged wildfire smoke (organic aerosol particles) on cirrus formation in the central Arctic (over the MOSAiC research icebreaker Polarstern) during the winter half year of 2019–2020. Aim of the simulations in part 2 is to gain a deeper and more detailed insight into the potential smoke impact on ice nucleation as a function of observed aerosol and meteorological conditions (temperature, relative humidity) and by considering realistic gravity wave characteristics (updraft speed, wave amplitude). Vertical movements of air parcels are essential to initiate cloud formation. The measurements presented in part 1 were conducted during the winter half year (October to March), aboard the ice breaker Polarstern. The research vessel Polarstern drifted with the pack ice in the central Arctic mainly at latitudes >85 °N during the winter half ...