Waves At The Southern Ocean Time Series (SOTS) Site

The Southern Ocean Time Series (SOTS) aims to provide information of biochemistry and ocean physics in the extreme Southern Ocean environment. As part of the SOTS program, the Southern Ocean Flux Station (SOFS) is responsible... [ view full abstract ]

The Southern Ocean Time Series (SOTS) aims to provide information of biochemistry and ocean physics in the extreme Southern Ocean environment. As part of the SOTS program, the Southern Ocean Flux Station (SOFS) is responsible for the wave measurements, among other physical parameters, and have been deployed 5 times (with fifth deployment currently at sea). a Motion Reference Unit (MRU) and a TriAxys directional wave sensor were installed to record acceleration and gyros from the buoy motion, from which it is possible to retrieve relevant wave information as significant wave height (Hs), wave peak period (Tp) and mean direction (D0). We here present the methodology applied on the data analysis as well as the main statistics and distribution of the wave parameters observed from the previous deployments, revealing the main Southern Ocean wave patterns. The most extreme events in terms of Hs found for each deployment are also investigated. We conclude that the main wave parameters present a very consistent distribution and statistics for the 3 deployments analysed. The predominance of wave propagation from Southwest is clear which reflects the westerly winds pattern. Hs , Tp and D0 mean and standard deviation was highly similar for all deployments. The highest events occurred during autumn and spring respectively and were closely related for the first 2 deployments. The last deployment however had a considerably lower extreme event, also occurring on autumn. Beside the wave parameters analysis we also characterised the wave spectra by their number of peaks. The occurrence of multi-peaks reveals the presence of different and coexisting wave system. The most common type of spectrum measured was uni-modal (~71 %), followed by double-peaked (~26 %) and 3 peaks spectrum (~3 %). By identifying the wind-sea peak, we conclude that most of the spectra were swell-dominated (~90%).