H2O GEOMATICS INC. (CA)
Lakes that form a seasonal ice cover are a major component of the terrestrial landscape. They cover approximately 2% of the Earth’s land surface, with the majority of them located in the Northern Hemisphere. The presence (or absence) of ice cover on lakes during the winter months affects both regional climate and weather events, such as lake-effect snowfall. Monitoring of lake ice is critical to our skill at forecasting high-latitude weather, climate, and river runoff as well as for ship navigation and transportation on winter ice roads. Lake ice cover (extent) and ice thickness have been identified as two ECVs by GCOS (2016). However, ground-based measurements of lake ice thickness are sparse in both space and time, and the number of sites where such measurements are made has dramatically decreased over the last two to three decades in many northern countries. In light of this and in support of GCOS, there is an urgent need to develop ice thickness products from satellite observations. Altimetry missions could play an important role in this respect, allowing for systematic measurements of ice thickness for many lakes of the globe.
The goal of this 12-month study is to pave the way for the eventual retrieval of lake ice thickness from satellite altimetry missions, supported by a thermodynamics lake ice model (CLIMo; Duguay et al., 2003) and a microwave radiative transfer snow model (SMRT; Picard et al., 2018). SMRT has recently been revised to include lake ice. The study will investigate the sensitivity of backscatter (σ0) and brightness temperature (TB) data collected by satellite altimetry missions to lake ice and on-ice snow properties. To meet this goal, the study will be divided into four main tasks: 1) review of the state-of-the-art in lake ice thickness retrieval as well as an analysis of requirements; 2) forward simulations of σ0 and TB using the latest active/passive version of the SMRT model; 3) comparison of SMRT model simulations with measurements from altimetry missions for a selection of North American and European lakes; and 4) formulation of conclusions and recommendations for future work (a roadmap), including the provision of various options for the development of retrieval framework. The framework could be applied, at a later stage (beyond the scope of this short study), to retrieve lake ice thickness from past, current and, eventually future altimetry missions such as Sentinel-6 and CRISTAL.