A new instrumental way to measure accumulating SWE in mountain and polar catchments directly, on the kilometre-scale and in near-real time

The Snow Water Equivalent (SWE) of snowfall is important but difficult to measure. While numerous techniques have been developed, measurements are still too sparse, too poorly distributed, too infrequent, too biased and too small to represent the variability of SWE in mountain landscapes. Snow pillows, pluviometers and other instruments have not solved this problem: precipitation products have large biases over mountain ranges worldwide. A novel measurement technique can now provide direct observations of snowfall SWE in polar and alpine settings accurately and on far larger spatial scales than most existing in situ methods, over areas comparable to model and satellite resolutions. By sensing water-pressure changes in lakes it is directly sensitive to the mass of new snowfall over the whole area of the lake, rather than a proxy for mass or a measurement at a point, and it is capable of high-frequency, high-resolution, low-cost and low-bias SWE measurements that do not saturate over time. Tests of this technique show it to be highly sensitive to falling snow, and highlight the sometimes-large errors present in conventional instruments, precipitation models and products. (Keywords: SWE, snowfall, lake, water, pressure).

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