Float Array for Submesoscales and Turbulence in ARCTERX
Abstract
Submesoscale (SMS) energy is elevated (a) on the peripheries of mesoscale features, (b) in topographic wakes, and (c) due to turbule nt thermal wind. In 2D quasigeostrophic flows, eddy kinetic energy (EKE) cascades to larger scales as small eddies coalesce. In 3D a geostrophic flows, EKE cascades to smaller scales and is dissipated as turbulence. Both occur simultaneously. Here we propose a prof iling float array for ARCTERX that contributes to quantifying downscale energy cascades from the SMS flows to determine the relative importance of internal gravity wave (IGW) and SMS currents in turbulence generation and to assess turbulence distributions in both time and space, including the role that turbulence plays in vorticity evolution and vice versa.To sustain coverage over months acros s spatial scales ranging from mesoscale eddies of O(200) km to turbulence of O(0.01-10) m, we will use an array of 15 existing SOLO- II profiling floats with CTDs and 8 Flippin Chi SOLO (FCS) floats fully instrumented with turbulence sensors and developed with ONR funding (2 exist, 6 to be constructed). This array will be deployed to attempt to quantify:1. the rate of the downscale cascade and mixing,2. turbulence generated by SMS currents in the interior, and3. coupling between SMS currents and IGWs.The float array will o btain the time-varying spatial structure of turbulence through and around an evolving SMS feature. Objective mapping of the measured density, temperature, salinity, surface velocity and depth-mean velocity fields will extend our assessment to the time-varying spic e, strain, vorticity, and divergence fields.Specifically, we propose the following contributions.1. SIO will manufacture 6 new FCS f loats with CTDs to which OSU will add an additional package that includes 2 shear probes, 2 thermistors and pitot tube for sensing t urbulence, pressure sensor, compass and 3-axis linear accelerometer package.2. 15 SOLO-II floats from FLEAT and CALYPSO are availabl e for ARCTERX. Two existing FCS floats built under ONR grant N00014-17-1-2700 require firmware upgrades for data exfiltration. These floats have already been fabricated and are ready for use in ARCTERX without further fabrication cost.3. We will deploy 5 SOLO-II a nd 5 FCS floats floats in 2023 field experiment. We intend to recover all FCS floats in 2023.4. We will develop the necessary on-boa rd processing to obviate the need for recoveries.5. We will deploy 10 SOLO-II and 8 FCS floats in 2024 field experiment. No floats w ill be recovered. These floats will be in the field for 3-12 months, depending on the mission.Budgets include construction costs of $385k (SIO) and $100k (OSU). These costs will be proposed to DURIP with the intent that they be subtracted from SIO and OSU ARCTERX budgets. Note: For clarity OSU and SIO proposals are identical since they are interdependent. Tasks are distinct and defined within . Budgets are separate.Approved for public release.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2021
- Source ID
- N000142112762
Entities
People
- S. Johnston
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego