Collaborating Institutions


Delft University of Technology

Florida State University

Georgia Tech University

Naval Postgraduate School

Naval Research Laboratory Stennis Space Center

Oregon State University

RSMAS, University of Miami

Scripps Institution of Oceanography


University of California, Los Angeles

University of Michigan

University of Southern Mississippi



Littoral Geosciences & Optics (Code 321)

Inner Shelf Dynamics

Office of Naval Research Departmental Research Initiative


The inner shelf region begins just offshore of the surf zone, where breaking by surface gravity waves dominate, and extends inshore of the mid-shelf, where theoretical Ekman transport is fully realized. In the inner shelf the surface and bottom boundary layers can overlap.

A wide range of processes is important in the inner shelf including: wind driven upwelling and downwelling, non-linear internal waves, heat, momentum and sediment fluxes from the surf zone via rip currents, surface wave breaking and Langmuir mixing, and bed stresses that suspend sediment and create bedforms. Each can affect the vertical properties of the water column here and the importance of each processes varies widely throughout the domain.

While the surf zone and the mid to outer shelf have been well studied, the connecting region of the inner shelf has not, largely due to the need to consider the large range of processes that are important and the logistics of operating in a relatively shallow environment.


Our main goal is to provide provide improved understanding and prediction of this difficult environment. This will involve efforts to assess the influence of the different boundaries - surf zone, mid and outer shelf, air-water interface, and bed - on the flow, mixing and stratification of the inner shelf. We will also gain information and predictive understanding of remotely sensed surface processes and their connection to processes in the underlying water column.


A combination of observation and modeling will be used in this research initiative including hydrostatic and non-hydrostatic models, airborne thermal and radar remote sensing, drifting measurement platforms, and in situ moorings.

The Inner-Shelf Dynamics Experiment

Kumar, N., and 49 others, including J. Thomson, M. Moulton, and C. Chickadel, "The Inner-Shelf Dynamics Experiment," Bull. Am. Meteorol. Soc., 102, E1033–E1063, doi:10.1175/BAMS-D-19-0281.1, 2021.

More Info

1 May 2021

The inner shelf, the transition zone between the surf zone and the mid shelf, is a dynamically complex region with the evolution of circulation and stratification driven by multiple physical processes. Cross-shelf exchange through the inner shelf has important implications for coastal water quality, ecological connectivity, and lateral movement of sediment and heat. The Inner-Shelf Dynamics Experiment (ISDE) was an intensive, coordinated, multi-institution field experiment from Sep.–Oct. 2017, conducted from the mid shelf, through the inner shelf and into the surf zone near Point Sal, CA. Satellite, airborne, shore- and ship-based remote sensing, in-water moorings and ship-based sampling, and numerical ocean circulation models forced by winds, waves and tides were used to investigate the dynamics governing the circulation and transport in the inner shelf and the role of coastline variability on regional circulation dynamics. Here, the following physical processes are highlighted: internal wave dynamics from the mid shelf to the inner shelf; flow separation and eddy shedding off Point Sal; offshore ejection of surfzone waters from rip currents; and wind-driven subtidal circulation dynamics. The extensive dataset from ISDE allows for unprecedented investigations into the role of physical processes in creating spatial heterogeneity, and nonlinear interactions between various inner-shelf physical processes. Overall, the highly spatially and temporally resolved oceanographic measurements and numerical simulations of ISDE provide a central framework for studies exploring this complex and fascinating region of the ocean.

Inner Shelf Dynamics Science and Experiment Plan

Feddersen, F., et al., "Inner Shelf Dynamics Science and Experiment Plan," APL-UW TR 1602, Technical Report, Applied Physics Laboratory, University of Washington, Seattle, October 2016, 35pp.

More Info

31 Oct 2016

The deep ocean, continental shelf, and surf zone are defined by their unique physical processes and dynamics. The nearshore region from about 50 m water depth to the outer edge of the surf zone (SZ) is known as the inner shelf. This region is characterized by overlapping and interacting surface and bottom boundary layers. At the offshore side of the inner shelf, instabilities from wind-driven currents and fronts create cross-shelf meanders and eddies. In addition, energetic nonlinear internal waves (NLIWs) are ubiquitous on the inner shelf.

To understand and predict the exchange of water properties (heat, gases, sediment, pollutants, biota) across the inner shelf over a range of temporal and spatial scales, the Office of Naval Research Inner Shelf Dynamics Departmental Research Initiative (Inner Shelf DRI) is coordinating field observations (in situ and remote sensing) coupled to numerical modeling efforts on a 50-km section of coast off Vandenberg Air Force Base, California, located in the vicinity of Point Sal. The overall goal is to develop and improve the predictive capability of a range of numerical models to simulate the 3D circulation, density, and surface wave field across the inner shelf associated with a broad array of physical processes and complex bathymetry.

North-looking view of the Point Sal, CA, study site with visible fronts generated by flow interactions with the headlands.