Rapid Hydrographic, Optical, and Microstructure Surveys

in the Middle Atlantic Bight

PIs: Jack Barth and Mike Kosro

COAS , Oregon State University

After this brief introduction appear reports on each of the data sets collected. Funding for this project was provided by ONR Grant N00014-95-1-0382. Inquiries about data availability may be directed to Jack Barth (barth@oce.orst.edu).

This project is part of the Office Of Naval Research "Coastal Mixing and Optics (CMO) Accelerated Research Initiative". The objective of the Coastal Mixing and Optics ARI is to quantify and understand the role of vertical mixing processes (in a laterally-varying environment) in determining the mid-shelf vertical structure of hydrographic and optical properties and particulate matter.

As part of the Coastal Mixing and Optics ARI, we are investigating spatial distributions of optical and microstructure properties on the continental shelf and relating them to larger scale features in the shelf density and velocity fields (e.g., wind-driven or geostrophic currents and fronts). By defining spatial variations in not only the continental shelf and slope circulation, but also in the optical and microstructure properties in this region we can determine the relationship between lateral processes and observed variations in local vertical mixing processes. To accomplish these objectives, we made contemporaneous measurements of density, light absorption/attenuation and microstructure using sensors mounted on SeaSoar, a towed undulating measurement platform. The SeaSoar sensor suite includes a dual-sensor Seabird CTD, a nine-wavelength light absorption and attenuation meter (WETLabs ac-9) and a new microstructure instrument (MicroSoar). Horizontal velocity is measured directly, at similar time and space scales as the hydrographic, optical and microstructure fields are measured, using a shipborne acoustic Doppler current profiler (ADCP).

We made rapid surveys during two 21-day field experiments in the Middle Atlantic Bight centered near 40.5N, 70.5W, south of Cape Cod, Massachusetts. A summer survey, when the shelf is stratified, was made from 14-Aug to 1-Sep 1996 and a spring survey, when the shelf water tends to be well-mixed and separated from offshore water by a shelf-slope front, was made from 25-Apr to 15-May 1997. During each field experiment we made repeated large-region surveys over a 80 x 70 km box, which we cover with high-resolution every 2 days. We also concentrated our measurements in a small 20 x 20 km box centered around a mid-shelf location where vertical mixing processes were intensively sampled by moored instrumentation and vertical profiling from a stationary ship.

Hydrographic (Seasoar) Data Report

Shipboard ADCP Data Report

ac-9 Optical (Seasoar) Data Report

Microstructure (Seasoar-MicroSoar) Data Report

Introductory CMO SeaSoar page
site maintained by: S. Pierce