Measuring sea ice concentration in the Arctic Ocean using SMOS

Other literature type English OPEN
Gabarro, Carolina ; Turiel, Antonio ; Elosegui, Pedro ; Pla-Resina, Joaquim A. ; Portabella, Marcos (2016)

We present a new method to estimate sea ice concentration in the Arctic Ocean using brightness temperature observations from the Soil Moisture Ocean Salinity (SMOS) interferometric satellite. The method, which employs a Maximum Likelihood Estimator (MLE), exploits the marked difference in radiative properties between sea ice and seawater, in particular when observed over the wide range of satellite viewing angles afforded by SMOS. Observations at L-band frequencies such as those from SMOS (i.e., 1.4&thinsp;GHz, or equivalently 21-cm wavelength) are advantageous to remote sensing of sea ice because the atmosphere is virtually transparent at that frequency. We find that sea ice concentration is well determined (correlations of about 0.75) as compared to estimates from other sensors such as the Special Sensor Microwave/Imager (SSM/I and SSMIS). We also find that the efficacy of the method decreases under thin sea ice conditions (ice thickness <<span style="position: relative;bottom:-.5em; left:-.80em;">~</span><i style=" margin-left:-.7em"></i>0.6&thinsp;m). This result is expected because thin ice is partially transparent at L-band thus causing sea ice concentration to be underestimated. We therefore argue that SMOS estimates can be a compelling complement to estimates of ice concentration of both thick and thin sea ice from other satellite sensors such as the Advanced Microwave Scanning Radiometer (AMSR-E and AMSR-2) or SSMIS, enabling a synergistic monitoring of pan-Arctic sea ice conditions.
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