Self- and Inter-Crossover Points of Jasons’ Missions as New Essential Add-on of Satellite Altimetry in the Sub-Arctic Seas and the Southern Ocean

For decades, satellite altimetry is providing reliable data on the sea level, surface currents, tides, planetary and wind waves and sea ice. We propose a potential enhancement of collecting special data subsets for a better temporal and spatial sampling of dynamics of the Sub-Polar seas. We show that peculiarities of the orbits of the TOPEX/Poseidon and Jasons’ missions generate a regular grid of crossovers which locations are fixed in space and time of the orbit cycles. Two types of these special crossovers are specified: self-crossovers (SC) occurring as intersections of tracks of the same satellite and inter-crossovers (IC) appearing during the phases of interleaved orbits when tracks of two different satellites are crossing. The time delay between two consecutive measurements in the high-latitude sites is less than 2 h for SC and 1 h for IC, thus providing a ground for monitoring large-scale currents (including current direction) and wind waves. The sets of the special crossovers can be regarded as networks of virtual ocean buoys. The Norwegian Sea case study illustrates the value of the special crossovers for the Sub-Polar seas and the feasibility of building the networks of SC and IC in other areas of the World Ocean

Wind waves in the North Atlantic from ship navigational radar: SeaVision development and its validation with the Spotter wave buoy and WaveWatch III

International audienceWind waves play an important role in the climate system, modulating the energy exchange between the ocean and the atmosphere and effecting ocean mixing. However, existing ship-based observational networks of wind waves are still sparse, limiting therefore the possibilities of validating satellite missions and model simulations. In this paper we present data collected on three research cruises in the North Atlantic and Arctic in 2020 and 2021 and the SeaVision system for measuring wind wave characteristics over the open ocean with a standard marine navigation X-band radar. Simultaneously with the SeaVision wind wave characteristic measurements, we also collected data from the Spotter wave buoy at the same locations, and we ran the WaveWatch III model in a very high-resolution configuration over the observational domain. SeaVision measurements were validated against co-located Spotter wave buoy data and intercompared with the output of WaveWatch III simulations. Observations of the wind waves with the navigation X-band radar were found to be in good agreement with buoy data and model simulations with the best match for the wave propagation directions. Supporting datasets consist of significant wave heights, wave directions, wave periods and wave energy frequency spectra derived from both SeaVision and the Spotter buoy. All supporting data are available through the PANGAEA repository - https://doi.org/10.1594/PANGAEA.939620 (Gavrikov et al., 2021). The dataset can be further used for validation of satellite missions and regional wave model experiments. Our study shows the potential of ship navigation X-band radars (when assembled with SeaVision or similar systems) for the development of a new near-global observational network providing a much larger number of wind wave observations compared to e.g. Voluntary Observing Ship (VOS) data and research vessel campaigns