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Ocean dynamics and thermodynamics in the tropical Indo- Pacific region

  • Author(s): Drushka, Kyla
  • et al.
Abstract

The Indonesian archipelago links the tropical Indian and western Pacific Oceans, so transmission of oceanic and atmospheric energy across the archipelago has the potential to impact both basins. The network of straits and passages within the archipelago provides a conduit for the transmission of ocean signals. To first order, relatively warm, fresh water flows from the Pacific into the Indian Ocean; this is known as the Indonesian Throughflow. Wave energy at a variety of timescales can impact the Indonesian Throughflow, with potential consequences for the entire Indo-Pacific region. Atmospheric signals can also be transmitted across the Indonesian archipelago. For example, the Madden-Julian Oscillation (MJO), a coupled system of strong convective and wind anomalies, propagates eastward from the western Indian Ocean through to the central Pacific Ocean at intraseasonal (30- to 90-day) timescales. The goal of this research is to characterize some of the ways in which oceanic and atmospheric energy is transmitted through the Indo-Pacific region. This thesis presents results from three studies that use in situ and satellite observations as well as simple models to examine these links. The effect of sub-surface topography is assessed through two studies that examine the properties of wave energy propagating into the Indonesian Throughflow region from the Indian Ocean. Pressure gauge measurements of two tsunamis demonstrate that the complex topography of the archipelago controls the propagation of high-frequency energy through dissipation, reflection, refraction, and resonant amplification. A study of Kelvin waves generated by wind anomalies over the equatorial Indian Ocean uses velocity and temperature measurements within the Indonesian archipelago to show that intraseasonal wave energy is also effectively controlled by bathymetry. Atmospheric links across the Indonesian archipelago are evaluated through an observational study of MJO dynamics. In situ observations from Argo profiling floats reveal the signature of the MJO on upper ocean temperature and salinity in both the Indian and western Pacific Oceans, illustrating that the atmosphere is an effective corridor for energy moving eastward over the Indo-Pacific region

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