Work

Decoupling air and water: how throughflow shapes mountain lake temperatures

Year: 2026

Type: article

Abstract: While mountain lakes are seen as sentinels of climate change, their thermal response may be less pronounced than their exposure and sensitivity initially suggest. We hypothesize herein that the snowmelt-generated throughflow explains the apparent decoupling between atmospheric and water temperatures in mountain lakes. This study quantifies the advective heat flux of Lake Lioson, a Swiss lake at 1,848 m elevation, over 2023–2024. We compare the advective heat flux, estimated using a water balance method, with the discrepancies between measured daily heat content changes and net vertical heat fluxes. During snowmelt, the lake heat storage was decoupled from the surface heat exchanges, with 33–42% of vertical heat flux lost to advection. Contrasting snowpack conditions between 2023 and 2024 resulted in a 10% difference in heat accumulation and a 3-meter variation in thermocline depth. The snowpack plays a key role in lake thermal dynamics, extending beyond snowmelt. Advective heat fluxes led to a cooling of up to 3.9 °C. Based on the seasonal contributions of vertical and advective heat fluxes, we propose a three-phase framework as a valuable basis for comparing the thermal responses of different alpine lakes to snow and atmospheric forcing.

Source: Inland Waters

DOI: 10.1080/20442041.2026.2634018

Authors: Isabel Elena Herr, Damien Bouffard, Marie-Elodie Perga

Institutions: University of Lausanne, Swiss Federal Institute of Aquatic Science and Technology

Language: English

Topic: Cryospheric studies and observations

Subfield: Atmospheric Science

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDG: Climate action

Open Access status: hybrid

Funder: Service de la Santé Publique, Canton de Vaud