The role of sub-mesoscale eddies and fronts in NIW generation, propagation and dissipation
Abstract
The primary objectives of NISKINE DRI are: factors controlling near-inertial energy input, which may include subtleties of the mixed layer, the sub-mesoscale, and the adjustment/breakdown associated with strong lateral variability; the assessment of non-wind source NIWs; decay and propagation of NIWs and associated turbulent mixing; and ability to use this information to refine upper ocean shear parameterizations. The proposed work addresses the NISKINE objectives by using a combination of theory and modeling, in collaboration with other PIs carrying out fieldwork. We will explore the following questions- How does the unforced generation of near-inertial waves from instabilities of sharp fronts compare with the wind-generated mechanism? Does forcing by air-sea buoyancy fluxes influence these results? Once generated, either by forced, or unforced mechanisms, what is the role of fronts in channeling and ducting the near-inertial fluxes? What is the ratio of the horizontally/vertically propagated near-inertial flux to the part that is lost to mixing or reabsorbed into the sub-inertial flow? The shear and stratification of the low-frequency (geostrophic) flow get modified by the near-inertial currents. What is the contribution of the near-inertial currents to increased mixing in different parts of the water column? These questions will be answered by a range of process modeling from meso scales to submesoscales, via a suite of process modeling experiments which will employ k-epsilon and other turbulent mixing models. The first set of sub-mesoscale resolving simulations will be without external forcing which allow sub-mesoscale and mesoscale eddies for the subpolar North Atlantic, where we expect spontaneously generated near-inertial waves near strong fronts based on our previous published work for the Kuroshio. We will then add wind-forcing, typical of Winter to Spring and Summer to Fall transitions in the sub-polar North Atlantic to analyze the interactions of these motions with the wind. Addition of air-sea surface buoyancy fluxes in the third set of simulations will provide guidance on the impact of these on the near-inertial waves. Our work will be collaborative with the overall NISKIN PI team, and we will query the models to help the measurements strategies for NISKINE fieldwork in 2019 and 2020.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 04, 2018
- Source ID
- N000141812799
Entities
People
- Amit Tandon
Organizations
- Office of Naval Research
- United States Navy
- University of Massachusetts