Fluctuations of Terra Nova Bay polynya as observed by active (ASAR) and passive (AMSR-E) microwave radiometers

This letter presents a first study of fluctuations in the extent of polynyas by means of two novel microwave instruments: the Advanced Synthetic Aperture Radar (ASAR) on the Envisat satellite and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on the Aqua satellite. ASAR images, with a spatial resolution of 150 m, offer a perfect view of polynya conditions but only a limited number of scenes is available in the ESA archive over a small area ( circa two scenes per month); AMSR images, with a spatial resolution of 6.25 km, allow the detection of polynya extent on a daily basis but with a much coarser accuracy. This study, while confirming the correlation between wind intensity and polynya area, suggests the possibility of using ASAR images to calibrate the 'open water' threshold in AMSR images for polynya size detection.