Development of SMAP Freeze/Thaw algorithms adapted for the Canadian tundra.

• Main Author: Bernier, Monique
• Format: Report
• Language: English
• Published: INRS, Centre Eau Terre Environnement 2015
• Subjects: seasonal Freeze/Thaw cycle; climate; boreal region; SMAP instrument; radiometer; Synthetic Aperture Radar (SAR); Arctic; Canada; permafrost; Tundra
• Online Access: https://espace.inrs.ca/id/eprint/6524/; https://espace.inrs.ca/id/eprint/6524/1/R1522.pdf

The seasonal Freeze/Thaw (F/T) cycle is a major phenomenon in the climate system and plays an important role in ecosystem functioning by influencing the rate of photosynthesis and respiration of the vegetation, reducing evaporation, reducing the penetration of water into the soil and altering surface runoff. Boreal and arctic regions form a complex land cover mosaic where vegetation structure, condition and distribution are strongly regulated by environmental factors such as soil moisture and nutrient availability, permafrost, growing season length and disturbance. In these seasonally frozen environments, the growing season is determined primarily by the length of the non-frozen period. Variations in both the timing of spring thaw and the resulting growing season length have been found to have a major impact on terrestrial carbon exchange and atmospheric CO2 source/sink strength in boreal regions. The frozen soil mapping can be improved by using the NASA SMAP instrument which includes both a Radiometer and a Synthetic Aperture Radar operating at L-band (1.20-1.41 GHz). In fact, SMAP will be able to monitor the frozen soil because of its capability to make coincident measurements of surface emission and backscatter, and with its ability to sense the soil conditions through moderate land cover. The accuracy, resolution, and global coverage of the SMAP mission should make possible a systematic updating of frozen ground maps and monitoring the seasonal F/T cycle. The main purpose of this project is to enhance the Canadian Plan for SMAP related F/T products by 1) supporting and augmenting an existing ground network in Northern Quebec as the main Cal/Val site related to F/T products in Canada and 2) developing and validating algorithms for the future SMAP mission to monitor F/T over the Tundra and the Boreal Forest using available time series of passive microwave and SAR L-band data. The Cal/Val site will provide field data for the development and validation of algorithms before and after the SMAP mission launch.