Daniel E. Frye

A Moored Profiling Instrument

Abstract The specifications and performance of a moored vertical profiling instrument, designed to acquire near-full-ocean-depth profile time series data at high vertical resolution, are described. The 0.8-m-diameter by 0.4-m-wide device utilizes a traction drive to propel itself along a standard mooring wire at a speed of ∼0.3 m s−1. The average power required to profile at this speed is 1–2 W; the present sensor suite and controller draw about 1.5 W. Based on these figures, the instrument’s battery capacity will support approximately 1 million meters of profiling. Instrument actions are regulated by an onboard microcontroller, allowing complex dive programs to be carried out. Oceanographic and engineering data are recorded internally on a hard disk interfaced to the controller. The measurement suite thus far deployed includes a CTD for deriving ocean temperature and salinity profiles, and an acoustic current meter that returns ocean velocity profile data. Addition of other oceanographic sensors is antic...

Ice-tethered profilers sample the upper Arctic Ocean

Studies conducted over the past decade indicate that the Arctic may be both a sensitive indicator of climate change and an active agent in climate variability. Although progress has been made in understanding the Arctics coupled atmosphere-ice-ocean system, documentation of its evolution is hindered by a sparse data archive. This observational gap represents a critical shortcoming of the ‘global’ ocean observing systems ability to quantify the complex interrelated atmospheric, oceanic, and terrestrial changes now under way throughout the Arctic and that have demonstrated repercussions for society [Symon et al., 2005]. Motivated by the Argo float program, an international effort to maintain an ensemble of approximately 3000 autonomous profiling instruments throughout the temperate oceans (see http://w3.jcommops.org), a new instrument, the ‘Ice-Tethered Profiler’ (ITP) was conceived to repeatedly sample the properties of the ice-covered Arctic Ocean at high vertical resolution over time periods of up to three years.

Mooring developments for autonomous ocean-sampling networks

Two general-purpose mooring designs have been developed to support autonomous underwater vehicle (AUV) operations in autonomous ocean sampling networks (AOSNs). These moorings provide two-way communications between investigators and AUVs docked on the moorings or conducting survey operations some distance from the moorings. A deep-water design that incorporates an AUV dock and recharging station was built for use in the Labrador Sea during the winter of 1997/1998. This severe winter environment required a robust design that could operate unattended for six months while isolating the dock from surface wave motion. A much lighter, easier-to-deploy design was developed for use in coastal waters to extend the nearshore AOSN operating area by extending the communications network. This coastal design has been deployed without the dock component and has typically been configured for use in a small network of moorings maintained with a small research vessel. The deep-water mooring has been deployed successfully on two occasions, for short periods of time. The coastal moorings have been deployed a number of times and have proven to be quite effective. This paper describes the two moorings in detail and provides information on their performance so that interested investigators can utilize the technology where it meets their needs.

Velocity measurements from a moored profiling instrument

Velocity profile measurements from a recently-developed moored profiling instrument are discussed. The WHOI Moored Profiler uses a traction drive system to propel itself along a standard subsurface mooring cable at a nominal speed of 0.3 m s/sup -1/. The instruments onboard controller supports complex sampling scenarios, limited chiefly by the configuration of the mooring and the capacity of the battery. The vehicle has thus far been equipped with a CTD and an acoustic travel-time current meter; data from the latter are examined. As part of this assessment, comparisons are made between velocity profile data obtained with moored profilers and those obtained from an expendable current profiler, the High Resolution Profiler, and a lowered acoustic Doppler profiler. The authors conclude with a summary of possible applications for the new instrument.

Recent developments in ocean data telemetry at Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution is developing techniques for telemetering oceanographic data from the deep ocean to the laboratory in near real time. Three general approaches that provide a link between subsurface instruments and surface buoys equipped with satellite transmitters are being pursued. These approaches are: cabled systems that use electromechanical cables to connect subsurface instruments to a central controller; high data rate acoustic modems to transfer information between multiple remote units and a central controller; and inductive modems that use standard mechanical mooring lines as the transmission medium between instruments deployed on the mooring and a central controller. These telemetry systems are targeted for general use by the oceanographic community and are designed to be power efficient, low in cost, and capable of integration with most oceanographic data collection systems. >

Design and operation of automated ice-tethered profilers for real-time seawater observations in the polar oceans

Funding was provided by the National Science Foundation under Contract Nos. OCE-0324233 and ARC-0519899.

A Wire-Guided, Free-Fall System to Facilitate Shipborne Hydrographic Profiling

Abstract The design and performance of a new style underwater frame for supporting instrumentation and water collection bottles used in hydrographic sampling is presented. Unlike a conventional frame that is fixed to the end of an electromechanical cable, the new frame is free to slide vertically along its tether. Allowing the frame to move relative to the sea cable decouples the underwater instrumentation from ship roll on downcast. Improved data quality from CTD instrumentation and the ability to work in more severe sea states result. Furthermore, the chance of cable damage that occurs when wire speed (lowering rate plus ship roll velocity) exceeds the terminal velocity of conventional underwater packages is greatly reduced. Absence of direct electrical connection to the underwater instrumentation necessitates an alternative scheme for real-time data display and command of water sample collection. These are accomplished with an acoustic telemetry system, implemented using commercially available components.

DEEPWATER MOORING DESIGNS FOR OCEAN OBSERVATORY SCIENCE

This paper describes the current state-of-the-art in mooring systems appropriate to the deepwater ocean observatory context. The technological challenges that need to be addressed in order to realize moored ocean observatories as envisioned for the next generation of ocean observing systems are outlined.

Surface Telemetry Engineering Mooring (STEM)

A mooring has been developed to collect and transmit oceanographic and meteorological data via satellite links. Data telemetered included currents (from 50 to 250 m), water and air temperature, wind, relative humidity, barometric pressure, and various engineering parameters. The unique aspect of the STEM design was the use of electromechanical cable for both the strength member of the mooring and the electrical connection between the subsurface instruments and the surface buoy. The surface mooring was deployed 150 m south of Cape Cod in 2700 m of water in November 1987 and retrieved in May 1988. It operated successfully through the harsh North Atlantic winter.<<ETX>>

Recent development in ocean data telemetry

Techniques for telemetering oceanographic data from the deep ocean to the laboratory in near real time are described. Three general solutions to the problem of how to transfer information between subsurface instruments and surface buoys equipped with satellite transmitters are discussed. Hardwired mooring techniques are discussed.<<ETX>>