Modelling the L-Band Snow-Covered Surface Emission in a Winter Canadian Prairie Environment

Alexandre Roy (1, 2, 3) , Marion Leduc-Leballeur (4) , Ghislain Picard (5) , Alain Royer (1, 3) , Peter Toose (6) , Chris Derksen (6) , Juha Lemmetyinen (7) , Aaron Berg (8) , Tracy Rowlandson (8) , Mike Schwank (9, 10)

1 CARTEL - Centre d'Applications et de Recherches en TELédétection [Sherbrooke]
2 Departement des sciences de l’environnement [Trois-Rivieres]
3 CEN - Centre d'Etudes Nordiques
4 IFAC - Institute of Applied Physics "Nello Carrara"
5 IGE - Institut des Géosciences de l’Environnement
6 Climate Research Division [Toronto]
7 FMI - Finnish Meteorological Institute
8 University of Guelph
9 Swiss Federal Institute for Forest, Snow and Landscape Research WSL
10 Gamma Remote Sensing Research and Consulting AG

Detailed angular ground-based L-band brightness temperature (TB) measurements over snow covered frozen soil in a prairie environment were used to parameterize and evaluate an electromagnetic model, the Wave Approach for LOw-frequency MIcrowave emission in Snow (WALOMIS), for seasonal snow. WALOMIS, initially developed for Antarctic applications, was extended with a soil interface model. A Gaussian noise on snow layer thickness was implemented to account for natural variability and thus improve the TB simulations compared to observations. The model performance was compared with two radiative transfer models, the Dense Media Radiative Transfer-Multi Layer incoherent model (DMRT-ML) and a version of the Microwave Emission Model for Layered Snowpacks (MEMLS) adapted specifically for use at L-band in the original one-layer configuration (LS-MEMLS-1L). Angular radiometer measurements (30°, 40°, 50°, and 60°) were acquired at six snow pits. The root-mean-square error (RMSE) between simulated and measured TB at vertical and horizontal polarizations were similar for the three models, with overall RMSE between 7.2 and 10.5 K. However, WALOMIS and DMRT-ML were able to better reproduce the observed TB at higher incidence angles (50° and 60°) and at horizontal polarization. The similar results obtained between WALOMIS and DMRT-ML suggests that the interference phenomena are weak in the case of shallow seasonal snow despite the presence of visible layers with thicknesses smaller than the wavelength, and the radiative transfer model can thus be used to compute L-band brightness temperature.

Mots clés: L-band emission; snow; WALOMIS; Frozen soil; ground-based radiometer

Domaines: Sciences de l'environnement

Alexandre Roy, Marion Leduc-Leballeur, Ghislain Picard, Alain Royer, Peter Toose, et al.. Modelling the L-Band Snow-Covered Surface Emission in a Winter Canadian Prairie Environment. Remote Sensing, 2018, 10 (9), pp.1451. ⟨10.3390/rs10091451⟩. ⟨hal-03747871⟩