title: Observations of sound-speed fluctuations on the New Jersey continental shelf in the summer of 2006.
abstract: Environmental sensors moored on the New Jersey continental shelf tracked constant density surfaces (isopycnals) for 35 days in the summer of 2006. Sound-speed fluctuations from internal-wave vertical isopycnal displacements and from temperature/salinity variability along isopycnals (spiciness) are analyzed using frequency spectra and vertical covariance functions. Three varieties of internal waves are studied: Diffuse broadband internal waves (akin to waves fitting the deep water Garrett/Munk spectrum), internal tides, and, to a lesser extent, nonlinear internal waves. These internal-wave contributions are approximately distinct in the frequency domain. It is found that in the main thermocline spicy thermohaline structure dominates the root mean square sound-speed variability, with smaller contributions coming from (in order) nonlinear internal waves, diffuse internal waves, and internal tides. The frequency spectra of internal-wave displacements and of spiciness have similar form, likely due to the advection of variable-spiciness water masses by horizontal internal-wave currents, although there are technical limitations to the observations at high frequency. In the low-frequency, internal-wave band the internal-wave spectrum follows frequency to the -1.81 power, whereas the spice spectrum shows a -1.73 power. Mode spectra estimated via covariance methods show that the diffuse internal-wave spectrum has a smaller mode bandwidth than Garrett/Munk and that the internal tide has significant energy in modes one through three.
authors.affiliation: Department of Oceanography, Naval Postgraduate School Monterey, California 93943, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Colosi
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Duda
authors.forename: Ying-Tsong
authors.initials: YT
authors.lastname: Lin
authors.forename: James F
authors.initials: JF
authors.lastname: Lynch
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Newhall
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Cornuelle