The dual nature role of the snow cover in rain on snow events and a note on latent heat
Abstract
Rain on snow events often cause flooding and are severe threats in many areas of the world. Analysing a case study in the Swiss Alps of 10 October 2011, we show that the status of the snow cover before the event can modify the runoff response significantly. In a region located in the Bernese Alps of Switzerland, a rather shallow snow cover was quickly turned into a melting snow cover and aggravated the runoff from warm precipitation causing local flooding and severe damage. Other regions in Switzerland, where the precipitation event had similar characteristics, were affected less, mainly because a much thicker snow cover was able to store some of the precipitation and therefore caused a more moderate runoff reaction. It is further shown that latent heat exchange has a significant role in the warming of the snow cover, amounting to approximately 50% of the total energy for melt. While this is a common characteristic of rain on snow events, it is often overlooked by snow modellers, especially those using temperature-index melt models. With climate change, rain on shallow alpine snow covers is expected to become more frequent and the process should be properly represented in warning scenarios.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.C33A0617W
- Keywords:
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- 0740 CRYOSPHERE / Snowmelt;
- 1821 HYDROLOGY / Floods;
- 4303 NATURAL HAZARDS / Hydrological