WHOI Funding and Awards --> Cecil H. and Ida M. Green Technology Innovation Awards --> 2001 Abstracts

Abstracts of 2001 Cecil H. and Ida M. Green Technology Innovation Awards

Infrared Remote Sensing of the Energy Dissipation Rate Due to Surface Wave Breaking
Christopher J. Zappa and John Trowbridge
Applied Ocean Physics & Engineering Department

Energy dissipation due to deep-water wave breaking plays a critical role in the development and evolution of the ocean surface wave field. Furthermore, the energy lost by the wave field via the breaking process is a source for turbulent mixing and air entrainment, which enhance air-sea heat and gas transfer. The present inability to measure energy dissipation due to wave breaking is a major impediment to improving global wave prediction models. Here we propose field experiments to quantify wave-breaking dynamics remotely by using an infrared imager to measure temperature changes due to the disruption and recovery of the aqueous surface thermal boundary, or skin, layer. This is the first attempt to combine infrared measurements of the recovery rate of the skin layer in the wakes of breaking waves and estimates of the dissipation rate due to breaking based on scaling arguments with direct turbulence-based measurements of the energy dissipation rates beneath breaking waves. This capability to remotely quantify the turbulent dissipation due to breaking waves will provide new insight into the turbulence-driven effects of breaking on air-sea transfer processes such as heat and gas flux.

In-Situ Time Series Measurements of Dissolved Phosphorus and Trace Metals Using an Automated Sampler and DGT
James W. Moffett and Gary R. Fones
Marine Chemistry & Geochemistry Department
and
Kenneth W. Doherty
Applied Ocean Physics & Engineering Department

Passive, in-situ sampling probes are a powerful tool for obtaining time-averaged concentration data for many key analytes in natural waters, such as phosphate. They enable us to detect phenomena which would be missed by periodic, discrete sampling, and eliminate many of the artifacts associated with sample handling and storage of water samples. Moffett and Fones are supported by EPA to use such a device, the diffusion gradients in thin-films (DGT) probe, to study contaminant transport in Boston Harbor. Probe deployments range from 6 hours to 1 week. Here, we request support to develop an automated sampling system to place the probes on moorings. A carousel of probes powered by a stepper motor will move round at pre-determined times to uncover the probes for exposure for periods of up to 6 days. It is envisaged that this automated sampler can be loaded with 20 probes, where two are exposed simultaneously, and can be deployed for a period of up to 60 days. The system can be left unattended for this period of time while valuable time series data is collected. It is analogous to a sediment trap sampler already built by Doherty and co-workers. The device can be used to study the temporal variability of metals, organic contaminants and phosphate in a variety of applications, but we are specifically interested in using it to study episodic inputs of phosphate into the euphotic zone in the Sargasso Sea.

Developing an Underwater Optical Communication System
Maurice Tivey
Geology & Geophysics Department
and
Paul Fucile
Physical Oceanography Department

We seek funds to construct, test and make quantifiable measurements of an underwater optical communication system that makes use of IrDA [Infrared Data Association] communication protocol technology. The use of optical communications underwater shows great potential for providing sensor interrogation and data download without the need for underwater electrical connections, close proximity of upload and download devices or the bandwidth limit of acoustic transducers. Optical communication technology could be used by submersibles, Remotely Operated Vehicles (ROVs), or even autonomous underwater vehicles (AUVs) on the fly to interact with sensors placed on the seafloor. Furthermore, it is feasible that smart sensors could also communicate with one another, to a central data-storage system or to a cabled network node. The key to development is to refine and understand the range of parameters that optimize optical communications underwater. We have designed a flexible "test-bed" system that we can vary basic parameters from baud rate to the number of transmission LEDs and types of photo-detectors. We seek funds to build this "test-bed" board and to carry out a range of underwater tests. The hardware is relatively inexpensive and the physical dimensions of a transmitter and receiver are small, about the size of a small flashlight. Thus, such an underwater communication system could be an unobtrusive and relatively inexpensive addition to a sensor package. The system could also be a way of standardizing a communication interface for underwater sensors.

Heat-Transfer Systems for Submerged Oceanographic Equipment
Glenn McDonald, Matt Naiman, and Dana Yoerger
Applied Ocean Physics & Engineering Department

Excessive heat is the enemy of solid-state electronic systems. It affects component longevity and efficiency in addition to introducing undesired drift in instrumentation. The high cost of deploying field gear makes increased reliability a necessity.

As more complicated electronic systems are being utilized for oceanographic research, their cooling and heat transfer requirements have grown considerably. Yet few changes in design have occurred other than making heat sinks and the like larger. These larger heat dissipation systems result in increased weight and volume of the effective payloads. The increased component density of electronics is adding to this trend as well. Improved computer modeling techniques combined with modem machine and fabrication techniques have potential for design and production of more volumetric- and weight-efficient heat-transfer structures that would benefit the AUV, ROV, manned submersible, and remote submerged observatory communities.