Abstract
Reflectometry measurements have been conducted aboard the German research icebreaker <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Polarstern</i> during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Signals of Global Navigation Satellite Systems (GNSS) were recorded using a dedicated GNSS reflectometry receiver for retrieval of sea-ice reflectivity. The primary goal is reflectometry-based monitoring of sea ice as a part of the Arctic climate study. The dataset presented here covers the expedition’s first leg (late September to mid-December 2019) in the Siberian Sector of the central Arctic (at about 82 ° N to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$87~^\circ $ </tex-math></inline-formula> N). Daily profiles of reflectivity are retrieved for satellite elevations <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$< 45^\circ $ </tex-math></inline-formula> . In agreement with model prediction, the results show best reflectivity contrast (about 5 dB between compact pack-ice and lower ice concentrations) for observations at left-handed circular polarization and elevation angles of 10°–20°. A daily resolved time series of sea-ice relative permittivity is inverted from the left-handed data. In general, the level of inversion results is at the lower limit of sea-ice values (relative permittivity of 3 and below), potentially indicating an influence of incoherent volume scattering. An occasional increase in the relative permittivity is attributed to the presence of water. Sea-ice profiles show anomalies that are confirmed by enhanced model prediction (slab reflection). A long-term comparison of prediction and retrieved profiles indicates anomalies’ dependence on ice thickness and temperature.
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