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Snow Falling on Alpine Lakes (SNOWFALL)

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Dr. Hamish Pritchard

Ice Dynamics and Paleo-climate Group
British Antarctic Survey
Cambridge UK

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Fellowship Period:  07.2019-06.2020

Research interests and main activities

My focus is on the two great glaciology issues: ice-sheet deglaciation and sea level rise, and the role and future of mountain glaciers as a water resource.

My ongoing work involves finding two of the major missing pieces in hydrology’s jigsaw: auditing glacier ice volumes on the river-basin scale using a new airborne radar survey platform that I have developed and have deployed successfully in the Nepal Himalayas; developing a better way to measure mountain snowfall (SWE) over much larger areas than has so far been possible. My technical background is in synthetic aperture radar and laser remote sensing, low-frequency radar field surveys of glaciers and ice sheets, GIS and mountain water resources.

These are tools that I apply in both a polar and alpine context, and the use of Antarctic research techniques and equipment to glaciers in High Mountain Asia fits well with the increasing focus of UK science on overseas development issues.


Activities within WSL Fellowship

My project with WSL involved developing a novel instrumental method for measuring snowfall. This is exciting because it finally provides a way to measure snow’s most important property – its water content – directly, and autonomously through snowstorms in mountains and polar regions, on what I call the ‘landscape scale’.

This work revolved around fieldwork in the Swiss Alps, deploying sensors in lakes either from the shore in summer or through the lake ice in winter, and making independent measurements of accumulated snow to test the method. WSL was the perfect collaborating institute for such work with a wealth of local expertise and equipment and, of course the ideal, a very well-connected laboratory on the doorstep. There can be no better place in the world to do this research.

The project was a great success and rapidly led to publication of our results in the Journal of Hydrometeorology (below). This would not have been possible without the tremendous support of Dr Daniel Farinotti and the late Professor Director Koni Steffen, to whom I am extremely grateful.


Title: Measuring changes in snowpack SWE continuously on a landscape scale using lake water pressure

Abstract: The seasonal snowpack is a globally important water resource that is notoriously difficult to measure. Existing instruments make measurements of falling or accumulating snow water equivalent (SWE) that are susceptible to bias, and most can represent only a point in the landscape. Furthermore the global array of SWE sensors is too sparse and too poorly distributed to be an adequate constraint on snow in weather and climate models. We present a new approach to monitoring snowpack SWE from time series of lake water pressure. We tested our method in the lowland Finnish Arctic and in an alpine valley and high-mountain cirque in Switzerland, and found that we could measure changes in SWE and their uncertainty through snowfalls with little bias and with an uncertainty comparable to or better than that achievable by other instruments. More importantly, our method inherently senses change over the whole lake surface, an area in this study up to 10.95 km2 or 274 million times larger than the nearest pluviometer. This large scale makes our measurements directly comparable to the grid cells of weather and climate models. We find, for example, snowfall biases of up to 100% in operational forecast models AROME-Arctic and COSMO-1. Seasonally-frozen lakes are widely distributed at high latitudes and are particularly common in mountain ranges, hence our new method is particularly well suited to the widespread, autonomous monitoring of snow-water resources in remote areas that are largely unmonitored today. This is potentially transformative in reducing uncertainty in regional precipitation and runoff in seasonally-cold climates.


Cooperation within WSL


Cooperation outside of WSL