The Southern Ocean has a profound impact on the Earth's climate system. Its strong winds, intense currents, and fierce waves are critical components of the air–sea interface and contribute to absorbing, storing, and releasing heat, moisture, gases, and momentum. Owing to its remoteness and harsh environment, this region is significantly undersampled, hampering the validation of prediction models and large-scale observations from satellite sensors. Here, an unprecedented data set of simultaneous observations of winds, surface currents, and ocean waves is presented, to address the scarcity of in situ observations in the region – https://doi.org/10.26179/5ed0a30aaf764 (Alberello et al., 2020c) and https://doi.org/10.26179/5e9d038c396f2 (Derkani et al., 2020). Records were acquired underway during the Antarctic Circumnavigation Expedition (ACE), which went around the Southern Ocean from December 2016 to March 2017 (Austral summer). Observations were obtained with the wave and surface current monitoring system WaMoS-II, which scanned the ocean surface around the vessel using marine radars. Measurements were assessed for quality control and compared against available satellite observations. The data set is the most extensive and comprehensive collection of observations of surface processes for the Southern Ocean and is intended to underpin improvements of wave prediction models around Antarctica and research of air–sea interaction processes, including gas exchange and dynamics of sea spray aerosol particles. The data set has further potentials to support theoretical and numerical research on lower atmosphere, air–sea interface, and upper-ocean processes.

A numerical model, based on the two-phase incompressible Navier–Stokes equations, is used to study transmission of regular water waves by a thin floating plate in two dimensions. The model is shown to capture the phenomenon of waves overwashing the plate, and the generation of turbulent bores on the upper plate surface. It is validated against laboratory experimental measurements, in terms of the transmitted wave field and overwash depths, for a set of incident wave periods and steepness values. Corresponding simulations are performed for a thick plate that does not experience overwash, which are validated using experiments where an edge barrier prevents thin-plate overwash. The model accurately reproduces (i) the linear relationship between the transmitted and incident amplitudes for the thick plate, and (ii) the decrease in proportion of incident-wave transmission for the thin plate, as incident steepness increases. Model outputs are used to link the decreasing transmission to wave-energy dissipation in the overwash, particularly where bores collide, and in the surrounding water, particularly at the plate ends. It is shown that most energy dissipation occurs in the overwash for the shortest incident waves tested, and in the surrounding water for the longer incident waves. Further, evidence is given that overwash suppresses plate motions, and causes asymmetry in plate rotations.

The sound radiated by newly formed bubbles can be used to determine their properties. However, details of the fluid dynamics driving the acoustic emission remain unclear. A neck-collapsing model has been proposed to explain the sound generation at bubble pinch-off. The model uses a forcing function which drives the Rayleigh-Plesset equation and is linked to the bubble acoustic pressure. Here, the model is tested on bubbles of diameter up to 7 mm generated in distilled water, tap water, and alcohol-water solution. The model works well for bubbles less than 2.2 mm radius but the error increases up to 71% for larger diameters.