Glider observations of circulation near abrupt topography
Abstract
The North Equatorial Current (NEC) of the Pacific ocean heads westward in the latitude range 9-16°N, where it encounters a series of ridges and islands. Also heading westward are propagating eddies and waves. The so-called “island rule” is a theoretical explanation for how wind stress to the east forces western boundary currents on islands. On the other hand, currents on an island’s western boundary may be caused by impinging mean or eddy flow. As these currents encounter topography, they may lead to a cascade through lee waves to the submesoscale. Island trapped waves are types of coastally trapped waves where the alongshore wavenumber is quantized to have an integral number of wavelengths around the island. While these trapped waves are known to be atmospherically forced, another interesting possibility is that flow past an island could cause them. In order to quantify and understand these processes, we propose to use gliders in an observational study targeted at: • the western boundary current off the east side of islands • the effect of westward propagating eddies and waves when they hit ridges and islands • waves and eddies caused by flow over ridges and past islands • island trapped waves We propose to use Spray underwater gliders to observe these processes. Gliders will be used either to survey by repeating a sequence of lines, or to hold station and act similarly to profiling moorings. The combination of spatial and temporal resolution provided by these glider missions will provide data relevant to the processes outlined above. Gliders will be outfit with sensors to measure pressure, temperature, salinity, and velocity. Year 1 will be devoted to experiment planning. Year 2 will include a full glider-year of observations. Depending on the results of year 1 evaluation, the gliders may be deployed to survey, hold station to allow time series, or in tandem to improve resolution for a shorter time. We anticipate 3-4 month missions in depths of 100-1000 m. Deployments will be done from small boats, while piloting may be done from anywhere with an internet connection. Years 3-4 will include two glider-years of operation each with 2 gliders in the water at all times. Year 5 will be devoted to scientific analysis and publication on the processes outlined above.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512488
Entities
People
- Daniel L. Rudnick
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego