Changes in Supersaturation Inside and Around Arctic Cirrus during Warm Air Intrusion Events

Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, 82234 Wessling, Germany Lead Author e-mail address: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 9 April 2026

Abstract

Cirrus clouds play a significant role in the radiative processes in the upper troposphere. Depending on the ambient conditions during their formation their micro- and macro-physical characteristics might differ, leading to different and potentially stronger radiative effects. In this study, we use airborne lidar measurements of cirrus clouds performed in the arctic during the HALO-(AC)3 campaign. We distinguish between two cirrus types depending on the ambient conditions during their formation. WAI cirrus, formed during a Warm Air Intrusion and AC cirrus under undisturbed arctic conditions. For these two groups we analyze the distribution of Relative Humidity over ice (RHi) for in-cloud and near-cloud data. We find that WAI cirrus are more frequently detected with high RHi over the threshold for homogeneous nucleation and also reach higher absolute values of RHi, both in the in-cloud and near-cloud regions. This could be indicative of younger clouds where ice nucleation is still ongoing.