Sea Ice Concentration Observed Low Microwave Frequency Radiometers

Abstract

The launch of the Soil Moisture and Ocean Salinity (SMOS) mission, in 2009, marked the dawn of a new type of space-based microwave observations. Although the mission was originally conceived for hydrological and oceanographic studies, SMOS is also making inroads in the cryospheric sciences by measuring the thin ice thickness. SMOS carries an L-band (1.4 GHz), passive interferometric radiometer (the so-called MIRAS) that measures the electromagnetic radiation emitted by the Earth's surface, at about 50 km spatial resolution, continuous multi-angle viewing, large wide swath (1200-km), and with a 3-day revisit time at the equator, but more frequently at the poles. AMSR-2 instrument is on JAXA ́s GCOM-W1 spacecraft, and was launched on 2012. AMSR-2 have radiometers working at several bands: 6.9, 7.3, 10.65, 18.7, 23.8, 36.5, and 89.0 GHz.An assessment on the differences on the sea ice concentration (SIC) maps obtained from low microwave frequencies radiometers, 6.9GHz (from AMSR-2) and SMOS, versus higher frequency (19Ghz and 37GHz) radiometers are presented. Despite its lower spatial resolution relative higher frequencies, SMOS-derived SIC products are little affected by the atmosphere and the snow (almost transparent at L-band). Moreover L-band measurements are more robust in front of the accelerated metamorphosis and melt processes during summer affecting the ice surface fraction measurements