Water temperature, mixing, and ice phenology in the arctic-alpine Lake Darfáljávri (Lake Tarfala), northern Sweden

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Kirchner, Nina, Weckström, Jan, Jansen, Joachim, Schenk, Frederik, Barnett, Jamie, Granebeck, Annika, Leppäranta, Matti, Korhola, Atte
• Format: Article in Journal/Newspaper
• Language: English
• Published: Uppsala universitet, Limnologi 2024
• Subjects: Tarfala; cryostratification; lake ice phenology; time-lapse imagery; lake temperature; Oceanography; Hydrology and Water Resources; Oceanografi; hydrologi och vattenresurser; Physical Geography; Naturgeografi; Arctic; Alpine Lake; Complex Lake; Antarctic and Alpine Research; Northern Sweden; Tundra
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-521198; https://doi.org/10.1080/15230430.2023.2287704

In the rapidly warming circumpolar Arctic, recent research of lakes has focused on their climatology and ecology but is challenged by sparsity of wintertime data. At the c. 48-m-deep and c. 0.5-km2 large proglacial Darfaljavri (Lake Tarfala), located in an arctic-alpine environment in the Scandinavian Mountains, year-round water temperatures were previously reported for 2016 to 2019. Here, this record is continued for 2019-2020 and 2021-2022, complemented by time-lapse imagery records of the state of the lake surface, as well as degree-day modeling of ice phenology (timing of ice-on and ice-off). Darfaljavri is cryostratified during winter, with interannual variations in the thermocline's thickness and temperature range. The ice season lasts from October to July. Modeled ice-on dates match observed ones reasonably well; however, observed ice-off dates occur much later than modeled ones, likely because of cold impact from Darfaljavri's glacial environment as inferred from a comparison with a close tundra lake. Though new insights into the complex lake mixing and ice phenology are provided, it remains to attribute the characteristics of Darfaljavri's winter stratification to additional potential drivers, such as lake ice thickness, atmospheric heat fluxes, and the water balance of the lake.