Soil moisture retrieval in the North Slope of Alaska from GCOM-W1/AMSR2 and Meteor-M No. 2/MTVZA-GYa radiometers data

In this paper, for the Arctic tundra region in the North Slope of Alaska, calibration of microwave emission model on the basis of AMSR2 and MTVZA-GYa radiometric data of the GCOM-W1 and Meteor-M No. 2 satellites, respectively were carried out. The GCOM-W1 and Meteor-M No. 2 brightness temperature data covered the period from January 1, 2012 to December 31, 2016 and January 1 to December 31, 2015, respectively. The peculiarity of the proposed calibration lies in the use of biomass vegetation and soil temperature estimations from the AMSR2 and the MTVZA-GYa radiometers observations with using empirical relationships. To estimate the vegetation biomass and soil temperature were proposed calibration curves linking brightness temperatures, measured by the radiometers, with the aboveground phytomass which was estimated from MODIS NDVI data, and with soil temperature which was measured by weather stations in-situ. As a result was shown that the proposed calibration allows to retrieve soil moisture at the test sites in North Slope of Alaska with determination coefficient of 0.46–0.52 and RMSE of 0.06–0.1 cm3/cm3. The study shows the potential possibility of carrying out the calibration of emission model, which improves the accuracy of the measurement of soil moisture in the Arctic region compared to existing satellite information products. This study demonstrates the possibility of using radiometer MTVZA-GYa on aboard of the Russian satellite Meteor-M No. 2 to measure soil moisture in the Arctic region. Found empirical relationships between brightness temperatures and surface soil temperature and aboveground phytomass at the test sites allows to predict these values from GCOM-W1 and Meteor-M No. 2 observations in the range of RMSE 53–54g/m2 and 1–1.5K, respectively.