| Variations in wind forcing over first-year sea ice (FYI) melt ponds occur at hourly to weekly scales and contribute to microwave backscatter (sigma°) variability observed from spaceborne synthetic aperture radar (SAR) platforms (e.g., ENVISAT-ASAR and RADARSAT-1). Small Perturbation Model (SPM) predictions of like-polarized, C-band sigma° from FYI melt ponds were derived from surface wind-wave height spectra for varying wind speeds, upwind fetch lengths, and melt pond depths. Significant scale surface roughness was observed even at wind speeds of 3 m s-1, resulting in sigma° (HH) ranging from -6 dB at 20° incidence to -24 dB at 50° incidence. Results from a multivariate linear regression analysis shows 53.4% of observed variance in sigma° (HH or VV) explained by wind speed, upwind fetch and pond depth, with no appreciable difference in the relative contribution of explanatory variables. Modeled omni-directional sigma° for 100 m transects elaborate the role of fetch and depth, as well as the modulating effect of hummocks, on sigma°. |
