Vertical velocity in submesoscale streamers from spatial surveys following a profiling float array
Abstract
Submesoscale activity is enhanced on the peripheries of mesoscale fronts and eddies, where horizontal gradients are strongest. Vertical velocity (w) is of order 10 m day????1 and transports properties across the mixed layer base. However, this w is challenging to observe amidst an ambient internal wavefield with w variability of order 1 cm s????1. Moreover, the submesoscale evolves over scales <1 day and <10 km. Therefore, high spatial and temporal resolution are needed. This project will use a combination of rapid spatial surveys from a ship and a rapidlyprofiling float array to assess w at an intense front across a range of scales: at mesoscale from the spatial surveys using quasigeostrophic approximations, such as the omega equation, _ in submesoscale streamers by tracking tracers (such as chlorophyll, salinity, spice, and potential vorticity) with finer spatial surveys and a float array, and _ due to internal waves from each float???s high-frequency w fluctuations. Repeated meso- and submesoscale-resolving surveys in the upper 200 m with Underway CTD (UCTD) and/or SeaSoar will follow an array of up to 8 SOLO-II floats at a mesoscale front and submesoscale streamers on its flanks during 3 cruises. A feature will be identified in an initial mesoscale UCTD or SeaSoar survey, a forecast model, and near-realtime satellite products, e.g., sea surface temperature and chlorophyll. The float array will be deployed in a submesoscale streamer in a box pattern and recovered after several days. Each float profiles to 200 m every 100 minutes and obtains about 400 profiles over a 30-day cruise. The submesoscale UCTD survey will follow the float array at the front. Cross-front sections of about 20-km length will be completed every 6 hours. Along each section, temperature and salinity profiles will be obtained at a horizontal resolution of about 250 m every 4 minutes. The whole suite of observations (mesoscale survey, float array, and submesoscale survey) will be relocated and repeated.This project will demonstrate the capability of an array of floats to gather dense hydrographic data to: (a) better understand of the transport of tracers and drifting objects due to the vigorous meso- and submesoscale circulation on the peripheries of eddies and fronts and (b) to improve local predictions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 10, 2018
- Source ID
- N000141812416
Entities
People
- S. Johnston
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego