Wind waves climatology of the Southeast Pacific Ocean

• Published in: International Journal of Climatology
• Main Authors: Aguirre, Catalina, Rutllant Costa, José, Falvey, Mark
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: Wave climatology; Swell; Wind sea; Atmospheric low level coastal jets; Southeast Pacific; Southern Ocean; Austral; Pacific
• Online Access: https://doi.org/10.1002/joc.5084; https://repositorio.uchile.cl/handle/2250/149386

The climatology of wind waves over the Southeast Pacific is analysed using a 32-year hindcast from the WaveWatch III model, complemented by satellite-derived significant wave height (SWH) and buoy measurements for validation. Using partitioned spectral data, a regional climatology of wind sea and swell parameters was constructed. In general, the simulated SWH shows a good agreement with satellite and in situSWH measurements, although the model appears to have a spatially uniform bias of approximately 0.3 m. The spatial pattern of SWH is clearly influenced by the meridional variation of mean surface wind speed, where the stronger winds over the Southern Ocean play a significant role generating higher waves at higher latitudes. Nevertheless, regional features are observed in the annual variability of SWH, which are associated with the existence of atmospheric coastal low-level jets off the coast of Peru and central Chile. In particular, the seasonal variation of these synoptic scale jets shows a direct relationship with the annual variability of SWH and with the probability of occurrence of wind sea conditions. Off the coast of Peru at approximately 15 degrees S the coastal low-level jet is strongest during austral winter, increasing the wind sea SWH. In contrast, off central Chile, there is an important increase of wind sea SWH during summer. The seasonal variation of the wind sea component leads to a contrasting seasonal variation of the total SWH at these locations: off Peru the coastal jet amplifies the annual variability of SWH, while off Central Chile the annual variability of SWH is suppressed by the presence of the coastal jet. Although the general conclusions of this research are considered to be robust, we discuss the limitations of the spectral partitioning method used to distinguish wind sea and swell-sea states. CONICYT through the PAI grant 79150062 Center of Excellence FONDAP 15110009 Ministry of Energy of the Government of Chile