The THINICE Field Campaign: Interactions between Arctic Cyclones, Tropopause Polar Vortices, Clouds, and Sea Ice in Summer

The THINICE field campaign, based in Svalbard in August 2022, provided unique observations of summertime Arctic cyclones, their coupling with cloud cover, and their interactions with tropopause polar vortices and sea ice conditions. THINICE was motivated by the need to advance our understanding of these processes and to improve coupled models used to forecast weather and sea ice, as well as long-term projections of climate change in the Arctic. Two research aircraft were deployed with complementary instrumentation. The Service des Avions Frangais Instruments pour la Recherche en Environnement (Safire) Aerei da Trasporto Regionale 42 (ATR42) aircraft, equipped with the radar-lidar (RALI) remote sensing instrumentation and in situ cloud microphysics probes, flew in the midtroposphere to observe the wind and multiphase cloud structure of Arctic cyclones. The British Antarctic Survey Meteorological Airborne Science Instrumentation (MASIN) aircraft flew at low levels measuring sea ice properties, including surface brightness temperature, albedo and roughness, and the turbulent fluxes that mediate exchange of heat and momentum between the atmosphere and the surface. Long-duration instrumented balloons, operated by WindBorne Systems, sampled meteorological conditions within both cyclones and tropospheric polar vortices across the Arctic. Several novel findings are highlighted. Intense, shallow low-level jets along warm fronts were observed within three Arctic cyclones using the Doppler radar and turbulence probes. A detailed depiction of the interweaving layers of ice crystals and supercooled liquid water in mixed-phase clouds is revealed through the synergistic combination of the Doppler radar, the lidar, and in situ microphysical probes. Measurements of near-surface turbulent fluxes combined with remote sensing measurements of sea ice properties are being used to characterize atmosphere-sea ice interactions in the marginal ice zone. SIGNIFICANCE STATEMENT: Arctic cyclones can span several thousand kilometers and last several weeks, bringing strong winds, clouds, and precipitation across the remote Arctic and affecting the sea ice through wind stress, surface energy budget, and snow cover. Therefore, they play a key role in Arctic weather and climate. Motivated by the need to improve the coupled environmental prediction, the representation of cyclones, and their influence on the rapidly changing Arctic climate, the THINICE field campaign intensively observed several Arctic cyclones in August 2022 by operating two aircraft and launching steerable balloons. Key measurements of fine-scale features within Arctic cyclones are highlighted including low-level jets along fronts, mixed-phase clouds containing multiple layers of supercooled water, boundary layer turbulent fluxes, and sea ice properties beneath the cyclones. The ability of state-of-the-art numerical models, with and without coupling to dynamic sea ice models, in representing these cases and coupled processes is the focus of the ongoing work with an aim to improve prediction capabilities. KEYWORDS: Atmosphere; Arctic; Sea ice; Clouds; Jets; Aircraft observations
1. Introduction The rapidly changing Arctic climate is one of the most alarming signals of global warming as it is having stark impacts on vulnerable ecological systems and indigenous people, [...]