INTERNAL TIDES OBSERVED AT 2-DEGREES-S-156-DEGREES-E BY IN-SITU AND TOPEX POSEIDON DATA DURING THE COUPLED OCEAN-ATMOSPHERE RESPONSE EXPERIMENT (COARE)/

During the enhanced monitoring phase of the Coupled Ocean-Atmosphere E xperiment (COARE), semidiurnal baroclinic tides were observed. At 2 de grees S-156 degrees E (1739 m depth)the Tropical Atmosphere-Ocean (TAO ) mooring outfitted with additional sensors from surface to bottom pro vides an interesting tool for describing the internal tides. M2, S2, a nd N2 baroclinic components were detected, explaining 59% of the semid iurnal variance on surface dynamic height. At the semidiurnal frequenc y, vertical displacements of isopycnals, highly variable in time, can reach 30 m and are mostly a combination of the M2, S2, and N2 internal waves. The two first baroclinic modes explain 70% of the variance in vertical displacement. M2 and S2 internal waves have different vertica l structure: M2 resembles the first baroclinic mode and S2 resembles t he second baroclinic mode. The M2 and S2 internal waves projected on t heir respective baroclinic mode are highly related to the modeled baro tropic tide. Two TOPEX/POSEIDON tracks cross over the mooring every 10 days, and the internal wave signature can be expected in sea level al ong the tracks despite the weakness of the signal. Sea level spectra a long both ascending and descending tracks show the existence of energy around the 250 km and the 120 km wavelength, respectively, which is i n accordance with a first baroclinic wave propagating northeastward, a s suggested in previous studies. From wavelet transform, the baroclini c tide signatures on the ascending (descending) track are centered aro und 2.5 degrees S (3.5 degrees S) with a 1 degrees (2 degrees) latitud inal extension, respectively, limited to the Ontong Java Plateau. We c onfirm the northeastward propagation of the baroclinic tides, and thei r source could be a series of islands parallel to the Kilinailau Trenc h or the large sloping topography between the Kilinailau Trench and th e Ontong Java Plateau.