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Working Toward Better Snowfall Mapping in Forested Areas

By: Kathleen Tuck   Published 3:13 pm / February 14, 2017

JP Marshall and colleague measuring snow properties.

HP Marshall, left, with Andy Gleason, performs ground-based radar observations by ski in Colorado’s Senator Beck Basin.

Boise State snow scientist HP Marshall is in Colorado working on a NASA project testing new approaches to mapping snow water equivalent in forested areas. SnowEx aims to better measure how much water is stored in snow-covered regions, the distribution of snow-water equivalent (SWE), and the snow energy balance in various conditions.

Marshall is working with a team headed by Edward Kim, Charles Gatebe, Amy Misakonis and Kelly Elder on the largest snow remote sensing effort in 15 years. Eight Boise State faculty and students are involved. The effort is led by NASA Goddard.

Taking density measurements in a snow bank.

Gus Goodbody takes a density measurement to determine the snow’s water equivalent.

Much of Earth’s snow cover is on forested land, challenging current remote sensing techniques, although newer techniques such as LiDAR and interferometric microwave radar show promise in these areas. Using these and other techniques, Marshall is helping to collect a unique dataset to help address scientific questions.

Work being done now is focused on gathering information from multi-sensor observations in dry snow conditions in Grand Mesa and Senator Beck, Colorado. Senator Beck, located in the San Juan mountains, consists of rugged complex terrain between 11,000 and 13,510 feet. This information will be compared with measurements taken in September 2016, when the ground was dry.

One question the group is trying to answer is at what point a sensing technique is overwhelmed by dense forest. To tackle this, they are observing an area with a confounding factor (ranging from no trees to a fully closed forest canopy) and a gradient free of variant factors like complex topography.

Kelly Elder, HP Marshall and Ludo Brucker stand in the snow.

Kelly Elder, HP Marshall and Ludo Brucker. Photo by Chris Hiemstra.

They also are looking at how the techniques work in other complex topography, and how the snow estimates from aircraft can be used to predict stream flow. Marshall is leading the ground effort at the secondary site in Senator Beck Basin to answer these two questions.

Successful algorithms developed to map forested terrain are expected to allow for data retrieval in previously inaccessible areas.

See video of Marshall and colleague Andy Gleason taking SWE, snow-depth and snow-layering measurements with portable radar at 13,000 feet in Senator Beck Basin for the NASA SnowEx mission.