Dataset: SF_adcp_1996
Deployment: SF_buoy_dep1

SF_adcp_1996

Principal Investigator:

Robert C. Beardsley (Woods Hole Oceanographic Institution, WHOI)

Jim Irish (Woods Hole Oceanographic Institution, WHOI)

Data Publisher:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI)

Project:

U.S. GLOBEC Georges Bank (GB)

Version:

20091210

Deployment Synonyms:

SFlank1

Version Date:

2009-12-10

Data URL:

https://osprey.bco-dmo.org/dataset-deployment/452967/data

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Description

"As part of the U.S. GLOBEC Northwest Atlantic/Georges Bank program, moorings were deployed on Georges Bank as part of the broad-scale survey component to help measure the temporal variability of both physical and biological characteristics on the Bank. The array consisted of a primary mooring site on the Southern Flank which was maintained for the full 5-year duration of the field program, plus secondary moorings, with fewer sensors and of shorter duration, in the well-mixed water on the Crest and in the cod/haddock spawning region on the Northeast Peak. Temperature and conductivity (salinity) were measured at 5-m intervals, ADCP velocity profiles were obtained with 1-m vertical resolution, and bio-optical packages (measuring fluorescence, optical transmission and photosynthetically active radiation) were deployed at 10-m and 40-m depths. Bottom pressure was measured at the Southern Flank site. The buoy design, sensors and mooring configuration is presented and discussed below, and the data obtained is presented and discussed in an accompanying report "U.S. GLOBEC Georges Bank Long-Term Moored Program: Data Report." (December 2005 WHOI-2005-11; " U.S. GLOBEC Georges Bank Long-Term Moored Program: Part 1 - Mooring Configuration" by J.D. Irish, S. Kerry, P. Fucile, R.C. Beardsley, J. Lord, and Ken Brink.)

"Long-term moorings were deployed on Georges Bank from the fall of 1994 through the summer of 1999. The Southern Flank site was occupied all years, the Crest just the first and the Northeast Peak the second, fourth and fifth years. Not all depths were occupied by all sensors at all times." (DRAFT REPORT - 27 April 2005, WHOI-2005-XX, "U.S. GLOBEC Georges Bank Long-Term Moored Program: Part 2 - Yearly Data Summary and Report" J.D. Irish, R.C. Beardsley, M. Caruso, R. Limeburner, and Ken Brink)

Methods & Sampling

Dataset acquisition description

The ADCP pinged at as high a rate as possible with the power available in the ADCP with auxiliary battery pack - 900 pings at 4-second intervals so that the expected uncertainty in the velocity measurement was less that 0.5 cm/sec. The 1-hour (or sometimes 0.5 hour) averaged horizontal velocities were measured in 1-m vertical bins from about 8-m depth to about 10 m above bottom. The loss at the top was due to blanking to remove transducer ringing, and the loss at the bottom was due to sidelobe reflection from the direct downward path to the bottom. The amplitude of the backscattered signal was also recorded in the 1-meter bins and used to monitor the time and depth changes in backscattered signal (related to biological scatterers in the water column). The ADCP also "saw" the instrumentation along the mooring line as side-lobe reflection contamination of the records. This was not apparent in short records (1 week), but becomes obvious with 6-month long record averages. The amplitude of the backscattered signal has an increased level and the Doppler velocities decreased at the depths of the sensors. The decreased velocity estimate is because the signal reflected from the stationary sensors has zero Doppler shift and biases the velocity estimate toward zero. (December 2005 WHOI-2005-11; " U.S. GLOBEC Georges Bank Long-Term Moored Program: Part 1 - Mooring Configuration" by J.D. Irish, S. Kerry, P. Fucile, R.C. Beardsley, J. Lord, and Ken Brink.)

Data Processing Description

Dataset Processing Description

Also see Southern flank velocity & temperature movies (1999)

ADCP_SF_1996-1999

More information about this dataset deployment

Funding

Award Number	Funding Source
unknown GB NOAA	National Oceanic and Atmospheric Administration
unknown GB NSF	National Science Foundation

Instruments

Acoustic Doppler Current Profiler

Supplied Description:

300-kHz RD Instruments Workhorse ADCP (Acoustic Doppler Current Profiler)

Instrument Type

Generic Name: Acoustic Doppler Current Profiler

Acronym: ADCP

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/115/

Generic Description:

The ADCP measures water currents with sound, using a principle of sound waves called the Doppler effect. A sound wave has a higher frequency, or pitch, when it moves to you than when it moves away. You hear the Doppler effect in action when a car speeds past with a characteristic building of sound that fades when the car passes. The ADCP works by transmitting "pings" of sound at a constant frequency into the water. (The pings are so highly pitched that humans and even dolphins can't hear them.) As the sound waves travel, they ricochet off particles suspended in the moving water, and reflect back to the instrument. Due to the Doppler effect, sound waves bounced back from a particle moving away from the profiler have a slightly lowered frequency when they return. Particles moving toward the instrument send back higher frequency waves. The difference in frequency between the waves the profiler sends out and the waves it receives is called the Doppler shift. The instrument uses this shift to calculate how fast the particle and the water around it are moving. Sound waves that hit particles far from the profiler take longer to come back than waves that strike close by. By measuring the time it takes for the waves to bounce back and the Doppler shift, the profiler can measure current speed at many different depths with each series of pings. (More from WHOI instruments listing).

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
mooring	mooring identification		mooring
year_start	starting year of sampling/operation, GMT		year_start
lat	latitude, in decimal degrees, North is positive, negative denotes South	decimal degrees	lat
lon	longitude, in decimal degrees, East is positive, negative denotes West	decimal degrees	lon
depth_w	water depth	meters	depth_w
depth	sampling depth	meters	depth
julian_day	Julian day as a decimal, for reference: Julian day 2440000 begins at 0000 hours, May 23, 1968		julian_day
yrday_gmt	GMT day and decimal time, as 326.5 for the 326th day of the year, or November 22 at 1200 hours (noon)		yrday_gmt
year	year, reported as YYYY, e.g. 1995		year
month_gmt	month of year, GMT time , i.e. 1-12		month_gmt
day_gmt	day, GMT time e.g. 22		day_gmt
hour_gmt	hours of time, GMT		hour_gmt
minute_gmt	minutes of time, GMT		minute_gmt
u	eastward velocity	centimeters/second	u
v	northward velocity	centimeters/second	v
w	vertical velocity	centimeters/second	no_bcodmo_term

Database

Contribute Data

Dataset: SF_adcp_1996
Deployment: SF_buoy_dep1

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: SF_adcp_1996Deployment: SF_buoy_dep1

Dataset acquisition description

Dataset Processing Description

Dataset: SF_adcp_1996
Deployment: SF_buoy_dep1