NWT RESEARCH DATABASE

Tags: physical sciences, hydrology, engineering, remote sensing, snow water equivalence

Objective(s): To advance the understanding of the Ku-band radar response to snow properties and develop improved retrieval algorithms using airborne sensors that replicate elements of the proposed spaceborne mission.

Project Description: High resolution Ku-band synthetic aperture radar (SAR) has been proposed to measure Snow Water Equivalent (SWE) from space as part of the proposed Canadian Space Agency Terrestrial Snow Mass Mission (TSMM). An opportunity exists to advance the understanding of the Ku-band radar response to snow properties and develop improved retrieval algorithms using airborne sensors that replicate elements of the proposed spaceborne mission. During the winter of 2012-2013, Environment and Climate Change Canada (ECCC) began this work with an evaluation of X- and Ku-band (9.6 and 17.2 GHz) radar response to snow covered tundra within Trail Valley Creek (TVC). The 2012-2013 campaign identified three areas of research that must be further explored to improve on the current understanding of snow-microwave interactions including: 1) exploration of complimentary microwave frequencies; 2) improved understanding of spatial variability in tundra snow microstructure; and, 3) characterization of tundra background (soil and vegetation) contributions. A multi-deployment field campaign is proposed to fill in the knowledge gaps identified by analysis of the 2012-2013 data. Below is a list of the research objectives/projects that will be lead by ECCC in collaboration with the University of Massachusetts and Wilfrid Laurier University: 1) to collect and validate novel 13.5 GHz InSAR measurements within the TVC basin; 2) to evaluate the response of InSAR in relation to variations in snow, soil, and vegetation properties with enhanced in situ and sensor network measurements; 3) to leverage existing snow-free lidar estimates of surface roughness and newly deployed soil sensor network to decompose background soil radar contributions; 4) to evaluate the influence of snow microstructure and snow stratigraphy on radar backscatter with local-scale quantitative measurements; and, 5) to establish meaningful snow and background input for microwave models and retrieval development. Airborne and ground based measurements will be acquired in close proximity to the Trail Valley Creek research station. The campaign will include four deployment phases, each with a central focus to address a gap in knowledge identified during the 2012-2013 work at TVC: 1) Deployment of the soil sensor network, 2) Airborne and ground-based snow measurement of shallow snow and the frozen soil background, 3) Airborne and ground-based snow measurement of the early-mid winter snowpack, and 4) Airborne and ground-based snow measurement of the mature mid-winter snowpack. An airborne radar system developed by the University of Massachusetts (UMass) will be flown to collect backscatter measurements of snow-covered tundra within the TVC watershed during Phases 2, 3 and 4. The Ku-band 13.2 GHz, single polarization, interferometric SAR system emulates a potential high-resolution spaceborne SAR configuration. Backscatter and phase information retrieved from the SAR will be combined with in situ snow and background soil measurements to decompose contributions to backscatter. The SAR system will be mounted onboard Northwright Airways (Norman Wells) Cessna 208 Grand Caravan aircraft, and is being proposed to be flown at an altitude of ~1000 m above ground level. A total of 3 days of flying, during each Phase is proposed. At the same time as the overflights of the UMass system are being flown, snow surveys documenting the snow depth, water equivalent, density, grain size, and layering will be conducted by a team of researchers on the ground. The goal is measure the same snow properties using both manual survey techniques on the ground and via the airborne SAR sensors overhead, multiple times, over the course of several days, at different times during the winter months. The researchers participating in this campaign will provide the Aurora Research Institute (ARI) with a copy of any published journals/articles/thesis related to this campaign. In collaboration with the research partners from Wilfrid Laurier, the research team will be looking to present an overview of the research project and the type of data that the team is collecting in March 2019 to the local community by presenting at the local school and/or community centre(s). The research team will be reaching out to these venues in-advance to make arrangements during the campaign. The data collected during this campaign will also be made available online as part of the Open Data initiative of the Canadian government with details to be provided to the ARI when they are posted. The fieldwork for this study will be conducted from February 8, 2019 to April 02, 2019.