Exploration of Thermal Bridging through Shrub Branches 1 in Alpine Snow

• Published in: Geophysical Research Letters
• Main Authors: Domine, Florent, Fourteau, Kévin, Choler, P.
• Other Authors: Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: snow; alders; ground temperature; shrubification; alpine greening; [SDE]Environmental Sciences; Arctic; Tundra
• Online Access: https://hal.science/hal-04308316; https://hal.science/hal-04308316/document; https://hal.science/hal-04308316/file/GRL-ChangesAccepted.pdf; https://doi.org/10.1029/2023GL105100

In the high Arctic, thermal bridging through frozen shrub branches has been demonstrated to cool the ground by up to 4°C during cold spells, affecting snow metamorphism and soil carbon and nutrients. In alpine conditions, the thermal conductivity contrast between shrub branches and snow is much less than in the Arctic, so that the importance of thermal bridging is uncertain. We explore this effect by monitoring ground temperature and liquid water content under green alders and under nearby alpine tundra in the Alps. During a January 2022 cold spell, the ground temperature at 5 cm depth under alders is 1.3°C colder than under alpine tundra. Ground water freezing under alders is complete, while water remains liquid under tundra. Finite element simulations reproduce the observed temperature difference between both sites, showing that thermal bridging does affect ground temperature also under Alpine conditions.