Time series of metocean variables derived form WAMOS (marine radar) data collected during the Antarctic Circumnavigation Expedition (ACE, https://spi-ace-expedition.ch/), from December 2016 to March 2017. Waves in the Southern Ocean are the biggest on the planet. They exert extreme stresses on the coastline of the Sub-Antarctic Islands, which affects coastal morphology and the delicate natural environment that the coastline offers. There is a lack of field data in the Sub-Antarctic and Antarctic Oceans. Thus, wave models are not well calibrated and perform poorly in these regions. Uncertainties relate to the difficulties to model the strong interactions between waves and currents (the Antarctic Circumpolar and tidal currents) and between waves and ice (reflected waves modify the incident field and ice floes affect transmission into the ice-covered ocean). Drawbacks in wave modelling undermine our understanding and ability to protect this delicate ocean and coastal environment. By installing a Wave and Surface Current Monitoring System (WaMoS II, a marine X-Band radar) on the research vessel Akademic Thresnikov and using the meteo-station and GPS on-board, this project has produced a large database of winds, waves and surface currents. Data were collected during the Antarctic Circumnavigation Expedition, which took place from Dec. 2016 to Mar. 2017. The dataset contains timeseries of relevant metocean variables divided in - Sea state and current parameters (PARA, MPAR) - Sea state and current parameters (PEAK, MPEK) - Ship course, position and speed (COURSE) - Wind speed and direction file (WIND) ********************************************************** Sea state and current parameters files (PARA, MPAR) File Name: -Prefix-_-rigID-_YYYYMM.txt - Prefix: 1) ‘PARA’ : spatial mean of the parameters (that pass the WaMoS II internal quality control) averaged over WaMoS II analysis areas (up to 9) placed within the radar field of view. 2) ‘MPAR’ : temporal average parameters calculated using all data collected during the past dt=20 minutes of the time specified in the file. - YYYY : Year. - MM : Month. - rigID : WaMoS II platform’s ID code (3 letters) Time reference: CPU clock. Values of missing parameters are set to -9, -9.0. List of parameters: - date : Date and TIME of acquisition (YYYYMMDDHHMMSS). - Hs : Significant wave height (m). - Tp : Peak wave period (s). - Tm2 : Mean wave period (s). - Lp : Peak wave length (m). - MDir : Mean wave direction (deg). - PDir : Peak wave direction (deg). - TpS : First swell system - wave period (s). - PDS : First swell system - peak wave direction (deg). - lpS : First swell system - peak wave length (m). - TpW : Wind sea peak wave period (s). - PDW : Wind sea wave direction (deg). - lpW : Wind sea wave length (m). - Usp : Surface current speed (m/s). - Udir : Surface current direction (deg). - IQ : Quality index, ranging from 0 ('no problems detected') to 999 ('images cannot be analysed'). - NSPEC : Number of averaged spectra. - INDEX : Quality index threshold (OK: IQ<Index). - Hmax : Maximum wave height (m). - Tlim : Limit period to separate Swell/Wind Sea (s). - ELEVL : Error number. - CFG-Date : Date/time of last wamos.cfg change (DD-MM-YYYY HH.MI.SS). ********************************************************** Sea state and current parameters files (PEAK, MPEK): File Name: -Prefix-_-rigID-_YYYYMM.txt - Prefix: 1) ‘PEAK’ : spatial mean of the parameters (that pass the WaMoS II internal quality control) averaged over WaMoS II analysis areas (up to 9) placed within the radar field of view. 2) ‘MPEK’ : temporal average parameters calculated using all data collected during the past dt=20 minutes of the time specified in the file. - YYYY : Year. - MM : Month. - rigID : WaMoS II platform’s ID code (3 letters) Time reference: CPU clock. Values of missing parameters are set to -9, -9.0. List of parameters: - date : Date and TIME of acquisition (YYYYMMDDHHMMSS). - Hs : Significant wave height (m). - Tp : Peak wave period (s). - PDir : Peak wave direction (deg). - Lp : Peak wave length (m). - HsW : Wind sea significant wave height (m). - TpW : Wind sea wave period (s). - PDW : Wind sea wave direction deg). - lpW : Wind sea wave length (m). - HSS1 : First swell system significant wave height (m). - Tps1 : First swell system: wave period (s). - PDs1 : First swell peak wave direction (deg). - lps1 : First swell peak wave length (m). - HSS2 : Second swell system significant wave height (m). - Tps2 : Second swell system: wave period (s). - PDs2 : Second swell peak wave direction (deg). - lps2 : Second swell peak wave length (m). - HSS3 : Third swell system significant wave height (m). - Tps3 : Third swell system: wave period (s). - PDs3 : Third swell peak wave direction (deg). - lps3 : Third swell peak wave length (m). - Us : Surface current speed (m/s). - Ud : Surface current direction (deg). - IQ : Quality index. - Tlim : Limit period to separate Swell/Wind Sea (s). - SPR : Mean wave spreading. - CSI : Cross sea index. - GAM : Enhancement factor of the jonswap spectrum. - NORI : from compass or GPS (0 = enable 1 = disable). - ELEVL : Error number - CFG-Date : Date/time of last wamos.cfg change (DD-MM-YYYYHH.MI.SS). ********************************************************** Ship course, position and speed file (COURSE): File Name: -Prefix-_-rigID-_YYYYMM.txt - Prefix: ‘COURSE’ : Input from NMEA systems. - YYYY : Year. - MM : Month. - rigID : WaMoS II platform’s ID code (3 letters) Time reference: CPU clock. Values of missing parameters are set to -9, -9.0. List of parameters: - date : Date and TIME of acquisition (YYYYMMDDHHMMSS). - LAT : Latitude (deg). - LONG : Longitude (deg). - GYROC : Ship gyro compass (deg). - GPS : GPS course (deg). - Shipsp : Ship speed (kn). - Depth : Water depth (m). - GPS-Speed : GPS-Speed (kn). - ASDPW : Internal parameter. ********************************************************** Wind speed and direction file (WIND): File Name: -Prefix-_-rigID-_YYYYMM.txt - Prefix: ‘WIND’ : Input from NMEA systems. - YYYY : Year. - MM : Month. - rigID : WaMoS II platform’s ID code (3 letters) Time reference: CPU clock. Values of missing parameters are set to -9, -9.0. List of parameters: - date : Date and TIME of acquisition (YYYYMMDDHHMMSS). - LAT : Latitude (deg). - LONG : Longitude (deg). - WIND SPEED : Wind speed (m/s). - DIR : Wind direction (coming from) (deg). - WIND SPEED10 : Wind speed at 10 meters height (m/s). - TRUE DIR : Wind direction relative to north (deg).

Reconstructed nonlinear surface from WAMOS (marine radar) data collected during the 3rd leg of Antarctic Circumnavigation Expedition, from the end of January to the end of March 2017. WAMOS data (AAS_4434_ACE_WAMOS) are processed with the Higher Order Spectral Method (HOSM) to provide the nonlinear surface elevation and the corresponding spectrum of waves during ACE. A Montecarlo approach is adopted to reproduce the natural variability of the sea state and gain reliable statistics of the underlying nonlinear surface elevation. Details on the method can be found on Toffoli, Alessandro, et al. "Evolution of weakly nonlinear random directional waves: laboratory experiments and numerical simulations." Journal of Fluid Mechanics 664 (2010): 313-336. File structure: Folder name corresponds to the time stamp of the input spectrum (yyyyMMddhhmmss) from AAS_4434_ACE_WAMOS. Each folder contains: 1. The surface elevation for 250 random realisations at 10 instant in times from initialisation saved every 5 dominant wave periods apart (0,5,10,15,…,50 Tp). The ten digits name is structured as 0000NRRttt where NRR is the number of the random realisation (from 1 to 250) and ttt denotes the time index (from 0 to 10). 2. NEW_SPECTRUM.DAT the 2D spectrum (64x64) as a columnar vector of the initial spectrum read from the AAS_4434_ACE_WAMOS. 3. INPUT_SPECTRUM.DAT the 2D spectrum (256x256) as a columnar vector of the initial spectrum for the HOSM. 4. WAVENUMBERSX.DAT and WAVENUMBERSY.DAT the wavenumber in x and y respectively 5. PP_INFO.DAT contains the peak period (Tp) in seconds 6. RUN_INFO.DAT contains the resolution in x of the WAMOS spectrum (64), the resolution in y of the WAMOS spectrum (64), the delta x for the surface elevation in m, the delta y for the surface elevation in m. Subsequent parameters are flags for the HOSM method. Waves in the Southern Ocean are the biggest on the planet. They exert extreme stresses on the coastline of the Sub-Antarctic Islands, which affects coastal morphology and the delicate natural environment that the coastline offers. In Antarctic waters, the sea ice cover reflects a large proportion of the wave energy, creating a complicated sea state close to the ice edge. The remaining proportion of the wave energy penetrates deep into the ice-covered ocean and breaks the ice into relatively small floes. Then, the waves herd the floes and cause them to collide and raft. There is a lack of field data in the Sub-Antarctic and Antarctic Oceans. Thus, wave models are not well calibrated and perform poorly in these regions. Uncertainties relate to the difficulties to model the strong interactions between waves and currents (the Antarctic Circumpolar and tidal currents) and between waves and ice (reflected waves modify the incident field and ice floes affect transmission into the ice-covered ocean). Drawbacks in wave modelling undermine our understanding and ability to protect this delicate ocean and coastal environment.