1A sea ice detection algorithm developed using UK TDS-1 Global Navigation Satellite Systems (GNSS)- newly formed sea ice, the scattering is mostly coherent which is typical for a mostly flat surface. In order to 7 measure the degree of coherence of the received waveform or DDM three different estimators are presented: 8 the normalized DDM average, the Trailing Edge Slope (TES), and the matched filter approach. Here we present 9 a probabilistic study based on a Bayesian approach using two different and independent ground-truth datasets. 10This approach allow us thoroughly assessing the performance of the estimators. The best results are achieved 11 for both the TES and the matched filter approach with a probability of detection of 97%, a probability of false 12 alarm of ∼ 2%, and a probability of error of 2.5%. However, the matched filter approach is preferred due to 13 its simplicity. The measurement of the sea ice concentration is also assessed in this work, but the nature of the 14 UK TDS-1 data (lack of calibrated data) does not allow us to make any specific conclusions about the sea ice 15 concentration. 16 Index Terms 17Sea Ice, coherent scattering, incoherent scattering, GNSS-R, UK TDS-1 18

Abstract-Since 1993, when the European Space Agency (ESA) proposed the use of GNSS reflected signals for sea mesoscale altimetry, a wide range of applications have appeared. This work focuses on the retrieval of Significant Wave Height (SWH) and the Mean Sea Surface Level (MSSL) from a ground-based experiment using the Interference Pattern Technique (IPT). Two different observables on the IPT are analyzed: the oscillation frequency, and the angle where coherency is lost. The point where coherency in the reflection process is lost can be related to the Rayleigh criterion for smooth surfaces and helps to determine the SWH. Spectral analysis on the interference pattern helps to determine the MSSL. A three-month field campaign was performed on the "Pont del Petroli" pier, Badalona, Spain, to see how the reflected GNSS signals were affected by coastal sea state, and check previous assumptions. Results from this field experiment are shown confirming that the SWH can be retrieved with an accuracy of 6 cm and the MSSL with 4 cm. Estimations of both parameters are obtained every 30 minutes approximately.

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For spaceborne Global Navigation Satellite SystemReflectometry (GNSS-R), the delay and Doppler frequency conditions dynamically change, so the compensation of the delay and Doppler errors using tracking is important to the altimetric and scatterometric performances. This work presents the characteristics of the delay and the Doppler frequency in spaceborne GNSS-R, such as the range of them, the Doppler spreading width, and the change rate. They are important considerations for design of the delay and Doppler tracking strategy. The characteristics of delay-Doppler conditions of spaceborne GNSS-R are presented with additional considerations for tracking design. The tracking methods are discussed, and the error impacts are visually demonstrated by using the spaceborne measured data from United Kingdom's Disaster Monitoring Constellation (UK-DMC) satellite.