Arctic Observations of Snow Water Equivalent with the Non-Contact Cosmic Ray Method

Abstract:

Snow plays a key role in the land surface energy budget, but accurate and spatially representative measurements are notoriously difficult to obtain, even in the most ideal circumstances. Snow data are particulalry lacking in the Arctic, where conditions are far from ideal, and where conventional technologies, including precipitation sensors, fail. The cosmic-ray technique, which has been successful in monitoring soil moisture, is also a promising way to measure snow water equivalent (SWE) depth in the Arctic. Because it has a large footprint (100s of meters in diameter) a cosmic-ray probe can average spatial heterogeneities, for example due to drifting snow, providing a big advantange over point sensors. Because it is non-invasive, it is well suited for mobile surveys. But does it work? Recent results from a tundra site near Barrow, Alaska show that the sensor is physically robust over the arctic winter, and yields reasonable SWE data. Snow pack built up gradually during the course of the winter, reaching a maximum of 2 cm SWE in mid May. I show how a cosmic-ray probe can be used in a mobile application, thus making it an an invaluable contribution to a ground-based Arctic observing platform.