Observations of Baroclinic Coastally Trapped Waves Around Islands at Low Latitudes

Low latitude island environments present a unique region to investigate the nature of coastal trapped waves. Phase speed and modal structure of trapped waves are governed by the local stratification and topography around the islands. Observations of temperature and water level were collected for a 12 month period in 2013 around the island nation of Palau located in the tropical West Pacific. Palau encompasses a large barrier reef with sleep offshore slopes and topographic variability in the along shore direction encompassing multiple headlands. During the observational campaign Typhoon Haiyan passed through the island chain providing a large broad band forcing to the oceanographic environment via sustained winds of 155 knots. The data suggest the presence of island-trapped internal waves which propagated around the perimeter of the barrier reef at a phase speed of ~4m/s. Isotherm heave greater than 25m was seen at each of the observation locations. Frequencies of the observed waves were near to super inertial. Recent work on coastal trapped waves has pushed the theory and observations past sub-inertial frequencies into the super-inertial range. These observations help provide insight to the nature of propagation of near and super-inertial trapped waves in the island environment.