Climate drivers of summer warming in Emerald Lake, Sierra Nevada, California

Mountain lakes experience extreme inter-annual climate variation as
well as rapidly warming air temperatures, making them ideal systems to
understand lake-climate responses. Snowpack and water temperature are
highly correlated in mountain lakes, but we lack a complete
understanding of underlying mechanisms. Motivated by predicted
declines in snowfall with future temperature increases, we
investigated how surface heat fluxes and lake temperature responded to
variation in snowpack, ice-duration, and weather in a typical high
elevation lake in the Sierra Nevada, California. Ice duration
determined the phenology of lake exposure to solar radiation, and was
the dominant mechanism linking snowpack to lake temperature. The
relative importance of heat loss fluxes (longwave radiation, latent
and sensible heat exchange) varied among wet and dry years. Declines
in snowpack and ice cover in mountain systems will reduce the scale of
variation in lake thermal responses and increase the responsiveness of
lake warming to atmospheric forcing.