NAUTICAL: Nearshore hydro-morphodynamics, Acoustics & Undersea Turbulence In Changing Atmospheric and Littoral conditions
Abstract
Battlespace environmental characterization is essential to the success of any naval engagement.This is particularly true in the western Pacific Ocean, where small islands increase environmentalcomplexity in an area of strategic interest to the U.S. Navy. Volcanicin origin, most westernPacific islands and atolls are surrounded by coral reefs that slope sharply seaward into irregularseafloor topography. These two environmental features, nearshore coral reefs and steeply slopingshorelines, create highly dynamic operating conditions that can change abruptly and unpredictably.The Nearshore hydro-morphodynamics, Acoustics & Undersea Turbulence In ChangingAtmospheric and Littoral conditions (NAUTICAL) research team will address open sciencequestions that challenge naval operating conditions near remote islands surrounded by coral reefsand steep seafloor gradients. We select Palmyra Atoll, in the equatorial central Pacific Ocean, asthe primary field site. Palmyra presents a unique opportunity to study wave energy cascades,shoreline variability, and ocean acoustics in a near-pristine environment devoid of most humaninterference for the last half century. Owned by The Nature Conservancy (TNC) since 2000,Palmyra has been the focus of reef and island conservation research, which complements the threetopic areas of our study: surface waves, beach morphology, and acoustics near steeply slopedislands and atolls. While the proposal is focusedon Palmyra, the field study can be shifted to thesecondary site, Palau, if necessary. Palau is selected due to its strategic importance, ongoingresearch, and established logistics infrastructure. Both sites support the focal points for our work:1. Surface wave spectra variability and wave energy dissipation around islands and atollsCoral reefs are effective in dampening and dissipating wave energy in nearshore environments.However, environmental stressors that change reef characteristics can reduce the amount of waveenergy a reef attenuates,and thereby increase coastal surge frequency, shift sediments, and altershoreline morphology. We will investigate these relationships in and around Palmyra Atoll.2. Beach morphology variability and temporal evolution around islands and atollsVariability in local coral health and regional wave conditions can have important implications fornearshore coastal morphology and inland vulnerability to extreme events. We will explore howbeach morphology varies spatially with sediment grain size, coral reef health, and offshore waveconditions, and temporally with changes in these characteristics as well as interannual andintraseasonal oscillations in large scale atmosphere and ocean processes.3. Acoustic propagation path variability near steeply sloped islands and atollsAcoustic propagation paths are complex in nearshore areas, especially in those with dynamicbottom topography and/or seafloor composition. In a three-part acoustic analysis, we will explorehow sound velocity profiles and acousticpropagation paths change from the nearshore to offshoreenvironments across the shelf break and into the open ocean region around Palmyra Atoll.As part of this program, we will integrate United States Naval Academy (USNA) undergraduatestudents (Midshipmen) following the model of the Training and Research in Oceanic andatmospheric Processes In tropical Cyclones (TROPIC) program, led by NAUTICAL Co-PISanabia and sponsored by ONR between 2011 and 2023. Our work also builds on prior studies ofthe interaction of flow with steep topography in/around the Palau Islandchain (Co-PI St. Laurent)and prior wave studies in/around Palmyra Atoll in 2013 (Monismith et al. 2015). Collaborationwith TNC and Palmyra Atoll Research Consortium leadership and researchers is ongoing.Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412733
Entities
People
- Louis St. Laurent
Organizations
- Office of Naval Research
- United States Navy
- University of Washington