Reflected signals of Global Navigation Satellite Systems (GNSS) have been investigated for various applications in remote sensing over the last three decades. The overall research field of GNSS reflectometry includes the retrieval of sea ice parameters as an important application. For this purpose, GNSS reflectometry data have been recorded over the Arctic Ocean with a dedicated receiver setup during the MOSAiC expedition (Multidisciplinary drifting Observatory for the Study of Arctic Climate). The setup was mounted on the German research icebreaker Polarstern (AWI, 2017) that drifted during nine months of the expedition with the Arctic sea ice.

The here described data set comprises the expedition’s first leg in autumn 2019. It includes the drift period of the ship from 27th September until 14th December at about 82°N to 87°N in the Siberian Sector of the Arctic. The data set is based on essential contributions of setup & data recording (by GFZ), maintenance & data transfer (by AWI and MOSAiC partners), processing to data level 1 & documentation (by DLR-SO). The level 1 data consist of GNSS signal power estimates of the direct and reflected signal. Data appear in event files (netcdf format) sorted into day folders. Each event includes observations of a satellite on a continuous track, here, in a satellite elevation range from min. 1° to max. 45°.

A dedicated GNSS reflectometry receiver, of GORS (GNSS Occultation Reflectometry Scatterometry) type, was used for the measurements. It is equipped with four antenna front-ends. A master channel and two slave channels are assigned to the front-ends. The master channel tracks the GNSS signal on the direct link. The slave channels are dedicated for observations of reflection events: one at left-handed (LH) and another one at right-handed (RH) circular polarization. The respective up-looking master antenna and port-side looking slave antenna (dual-polarization) are set up with a short baseline on the ship’s observation deck, about 22 m above the water level. The given ship-based geometry results in events with rather short excess paths of the reflected signal relative to the direct signal, much less than the range of a code chip (about 300 m for GPS L1 C/A). Interferometric pattern of direct and reflected signal contributions are observed in the channel. A separation step is required in further processing.