Antarctic Circumnavigation Expedition 2017: WAMOS data product

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).