Irradiance and temperature drive melt date shifts in Northern Finnish snow cover

Research has revealed that both irradiance and temperature have comparable effects on the melt-out-date (MOD), while a significantly higher concentration of light-absorbing particles (LAP) in the snow is required to produce a similar result. This is because the time LAP have available to impact snow conditions is relatively short in Northern Finland, and the snow naturally darkens with age, increasing its absorption of incoming irradiance.

Photo: Pasi Markkanen

The retreat of snow is of great importance for Northern Finland, being interlinked with regional hydrology, and affecting various parameters within ecosystems, as well as various human activities. This study evaluated the complex processes influencing snow cover and the MOD for Northern Finland.

Using a novel conceptual framework, scientists simplified these processes, dividing the snow season into just two periods. The reduction in snow depth was then parameterized based on three key variables: average temperature, incoming shortwave irradiance, and LAP deposition in the snow.

The findings demonstrate that annual variations in precipitation, average temperature, and irradiance all exert a similar influence on MOD. As these variables are interconnected in a changing climate, where temperature, clouds, precipitation, and irradiation are interdependent, they may effectively mask trends in one another through compensating effects.

In summary, these results enhance our understanding of snow cover dynamics in Northern Finland and underscore the intricate network of climate variables influencing these changes. These findings are crucial for anticipating and addressing the consequences of climate change in the Arctic region.

Further information:

Jonas Svensson, researcher, Finnish Meteorological Institute, jonas.svensson@fmi.fi

The scientific article is available in Science of The Total Environment.

Full citation of publication: Ström J., Svensson J., Moosmüller H., Meinander O., Virkkula A., Hyvärinen A., Asmi E.: Snow cover duration in northern Finland and the influence of key variables through a conceptual framework based on observed variations in snow depth, Science of The Total Environment, 903, 166333, doi.org/10.1016/j.scitotenv.2023.166333.

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