Valdes James R.

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Site L SOFAR float experiment, 1982-1985

(Woods Hole Oceanographic Institution, 1987-12) Price, James F. ; McKee, Theresa K. ; Owens, W. Brechner ; Valdes, James R.

Lagrangian measurements of low frequency currents in the vicinity of the Gulf Stream and its recirculation region in the western Sargasso Sea were made by tracking SOFAR floats. These floats were tracked using acoustic time of arrival information from an array of five Autonomous Listening Stations {ALSs) which were moored in the western Sargasso Sea. The ALSs performed almost flawlessly, returning over 90 percent of the possible data. Floats were released in three deployments of seven floats each in November 1982, February 1983, and June 1983. The floats were launched in initially coherent arrays (approximately 20 km spacing) at 34°N, 70°W, Site "L", and were ballasted for 700 m depth. The SOFAR floats themselves functioned with somewhat less than expected reliability; four floats failed fairly soon after launch, and several other floats suffered failures of their temperature and pressure telemetry. The majority of the SOFAR floats launched in this program produced long, and interesting trajectories. These new data will be valuable for estimating first order flow statistics in the dynamically important recirculation region, for visualizing interactions between the Gulf Stream and the New England Seamount Chain, and for estimating one and two particle diffusivities in a region of very high eddy energy.
FASINEX (Frontal Air-Sea Interaction Experiment) moored instrumentation

(Woods Hole Oceanographic Institution, 1989-02) Trask, Richard P. ; Dean, Jerome P. ; Valdes, James R. ; Marquette, Craig D.

In 1986, FASINEX, a Frontal Air-Sea Interaction Experiment, a multi-investigator cooperative experiment, was conducted to study the role of horizontal variability in air-sea interaction in the persistent front formed in the subtropical convergence zone south of Bermuda. Aimed at investigating all aspects of the atmospheric and oceanic variables related to the formation and maintenance of the front, an array of meteorological and current meter moorings was deployed by the Woods Hole Oceanographic Institution Buoy Group in 5400 meters of water . Two subsurface current meter moorings were deployed in October, 1984; five surface meteorological and current meter moorings and four Profiling Current Meter (PCM) moorings were set in January 1986 . All except one PCM mooring, which was lost, were recovered in June 1986. This report discusses the extensive preparations of, and modifications to, the Woods Hole Oceanographic Institution Buoy Group instruments placed on the five surface moorings. The equipment included 30 vector measuring current meters, ten vector averaging current meters and five vector averaging wind recorders .
Status report on MicroSat data telemtery

(Woods Hole Oceanographic Institution, 1992-06) Valdes, James R.

The intent of this project was to test and evaluate a new data collection concept; that of utilizing a "store and forward" message system in a low earth orbiting satellite, and to determine its suitabilty for oceanographic data telemetry. This new generation of satellites, dubbed "MicroSats" because of their small size (a 9 in. cube), was developed by the Amateur Radio Satellite Corporation (AMSAT) to complement the existing HF and VHG terrestral Packet data switching networks.
An autonomous, in situ light-dark bottle device for determining community respiration and net community production

( 2018-03) Collins, James R. ; Fucile, Paul D. ; McDonald, Glenn ; Ossolinski, Justin E. ; Keil, Richard G. ; Valdes, James R. ; Doney, Scott C. ; Van Mooy, Benjamin A. S.

We describe a new, autonomous, incubation-based instrument that is deployed in situ to determine rates of gross community respiration and net community production in marine and aquatic ecosystems. During deployments at a coastal pier and in the open ocean, the PHORCYS (PHOtosynthesis and Respiration Comparison-Yielding System) captured dissolved oxygen fluxes over hourly timescales that were missed by traditional methods. The instrument uses fluorescence-quenching optodes fitted into separate light and dark chambers; these are opened and closed with piston-like actuators, allowing the instrument to make multiple, independent rate estimates in the course of each deployment. Consistent with other studies in which methods purporting to measure the same metabolic processes have yielded divergent results, respiration rate estimates from the PHORCYS were systematically higher than those calculated for the same waters using a traditional two-point Winkler titration technique. However, PHORCYS estimates of gross respiration agreed generally with separate incubations in bottles fitted with optode sensor spots. An Appendix describes a new method for estimating uncertainties in metabolic rates calculated from continuous dissolved oxygen data. Multiple successful, unattended deployments of the PHORCYS represent a small step toward fully autonomous observations of community metabolism. Yet the persistence of unexplained disagreements among aquatic metabolic rate estimates — such as those we observed between rates calculated with the PHORCYS and two existing, widely-accepted bottle-based methods — suggests that a new community intercalibration effort is warranted to address lingering sources of error in these critical measurements.
SOFAR float Mediterranean outflow experiment data from the second year, 1985-86

(Woods Hole Oceanographic Institution, 1988-09) Zemanovic, Marguerite E. ; Richardson, Philip L. ; Valdes, James R. ; Price, James F. ; Armi, Laurence

In October, 1984, the Woods Hole Oceanographic Institution SOFAR float group began a three-year-long field program to observe the low frequency currents in the Canary Basin. The principal scientific goal was to learn how advection and diffusion by these currents determine the shape and amplitude of the Mediterranean salt tongue. Fourteen floats were launched at a depth of 1100 min a cluster centered on 32°N, 24°W, and seven other floats were launched incoherently along a north/south line from 24°N to 37°N. At the same time investigators from Scripps Institution of Oceanography and the University of Rhode Island used four other SOFAR floats to tag a Meddy, a submesoscale lens of Mediterranean water. In October, 1985, seven additional floats were launched, four in three different Meddies, one of which was tracked during year 1. This report describes the second year of the floats launched in 1984 and the first year of the ones launched in 1985. Approximately 41 years of float trajectories were produced during the first two years of the experiment. One of the striking accomplishments is the successful tracking of one Meddy over two full years plus the tracking of two other Meddies during the second year.
Gulf Stream recirculation experiment - Part II

(Woods Hole Oceanographic Institution, 1989-09) Wooding, Christine M. ; Owens, W. Brechner ; Zemanovic, Marguerite E. ; Valdes, James R.

This report presents trajectories and time series of velocity, pressure, and temperature for twelve neutrally-buoyant floats launched during the Gulf Stream Recirculation EXperiment (GUSREX) and two from earlier experiments, that continued to operate after May 1982. These float data were obtained from Autonomous Listening Stations (ALSs) deployed from May 1982 to August 1985.
An FSK telemetry module for vector measuring current meters

(Woods Hole Oceanographic Institution, 1987-12) Fucile, Paul D. ; Valdes, James R.

The EG&G Vector Measuring Current Meter (VMCM) used in mooring work provides a 20 ma Serial ASCII Instrumentation Loop (SAIL) communication system. A projected application of the VMCM is to have a surface mooring communicate with a series of VMCMs via a Frequency Shift Keying (FSK) link. While an FSK modem can communicate with the VMCM. a problem exists with the general operation of the VMCM. If the VMCM is addressed to dump data; it remains on until the unit is re-addressed. If a failure in the link occurs. then the VMCM stays on in . a higher power mode and the batteries will be depleted early. The insertion of a processing block between the modem the VMCM provides a way to look at incoming data. qualify it re-transmit it to the VMCM. The VMCM will reply and preprocessor can channel the data to the modem. In the event VMCM malfunction. the preprocessor has a timeout function will turn off the carrier keeping the line quiet.
Revisiting carbon flux through the ocean's twilight zone

(American Association for the Advancement of Science, 2007-04-27) Buesseler, Ken O. ; Lamborg, Carl H. ; Boyd, Philip W. ; Lam, Phoebe J. ; Trull, Thomas W. ; Bidigare, Robert R. ; Bishop, James K. B. ; Casciotti, Karen L. ; Dehairs, Frank ; Elskens, Marc ; Honda, Makio C. ; Karl, David M. ; Siegel, David A. ; Silver, Mary W. ; Steinberg, Deborah K. ; Valdes, James R. ; Van Mooy, Benjamin A. S. ; Wilson, Stephanie E.
SOFAR float Mediterranean outflow experiment data from the first year, 1984-1985

(Woods Hole Oceanographic Institution, 1986-07) Price, James F. ; McKee, Theresa K. ; Valdes, James R. ; Richardson, Philip L. ; Armi, Laurence

In October, 1984, the Woods Hole Oceanographic Institution SOFAR float group began a three-year long field program to observe the low frequency currents in the Canary Basin. The principal scientific goal was to learn how advection and diffusion by these currents determine the shape and amplitude of the Mediterranean salt tongue. Fourteen floats were launched at a depth of 1100 min a cluster centered on 32N, 24W, and seven other floats were launched incoherently along a north/south line from 24N to 37N. At the same time investigators from Scripps Institution of Oceanography and the University of Rhode Island used four other SOFAR floats to tag a submesoscale lens of Mediterranean water. Slightly over twenty years of float trajectories were p reduced during the first year of the experiment. In this report we briefly describe the 1984 field operations and show the first year's SOFAR float data. Perhaps the most striking result is that westward flow within the Mediterranean salt tongue was found to be confined to a rather narrow jet {roughly 150 km in meridional extent) which had a mean speed of roughly 2 em s -l. To the north or south of this jet the mean flow was much weaker and eastward. This suggests that currents associated with the salt tongue itself {rather than the gyre scale circulation) may be most important for determining the salt distribution.
The neutrally buoyant sediment trap: two decades of progress

(American Meteorological Society, 2020-05-21) Estapa, Margaret L. ; Valdes, James R. ; Tradd, Kaitlyn ; Sugar, Jackson ; Omand, Melissa M. ; Buesseler, Ken O.

The biological carbon flux from the ocean’s surface into its interior has traditionally been sampled by sediment traps, which physically intercept sinking particulate matter. However, the manner in which a sediment trap interacts with the flow field around it can introduce hydrodynamic biases, motivating the development of neutral, self-ballasting trap designs. Here, the performance of one of these designs, the neutrally buoyant sediment trap (NBST), is described and evaluated. The NBST has been successfully used in a number of scientific studies since a prototype was last described in the literature two decades ago, with extensive modifications in subsequent years. Originated at Woods Hole Oceanographic Institution, the NBST is built around a profiling float and carries cylindrical collection tubes, a feature that distinguishes it from other neutral traps described in the literature. This paper documents changes to the device that have been implemented over the last two decades, including wider trap tubes; Iridium Communications, Inc., satellite communications; and the addition of polyacrylamide gel collectors and optical sedimentation sensors. Information is also provided with the intent of aiding the development of similar devices by other researchers, including the present adaptation of the concept to utilize commercially available profiling float hardware. The performance of NBSTs built around commercial profiling floats is comparable to NBSTs built around customized floats, albeit with some additional operational considerations. Data from recent field studies comparing NBSTs and traditional, surface-tethered sediment traps are used to illustrate the performance of the instrument design. Potential improvements to the design that remain to be incorporated through future work are also outlined.
WHOI 260Hz Sound Source - Tuning and Assembly

(Woods Hole Oceanographic Institution, 2021-04) Valdes, James R. ; Furey, Heather H.

Sound sources are designed to provide subsea tracking and re‐location of RAFOS floats and other Lagrangian drifters listening at 260Hz. More recently sweeps have been added to support FishChip tracking at 262Hz. These sources must be tuned to the water properties where they are to be deployed as they have a fairly narrow bandwidth. The high‐Q resonator’s bandwidth is about 4Hz. This report documents the tuning, and provides an overview of the sound source assembly.

Valdes James R.

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