Dataset: CTD_MOCNESS.25
Deployment: AL9403II

CTD data collected during MOCNESS hauls, Georges Bank, 1993-1997

Principal Investigator:

Dr Greg Lough (National Marine Fisheries Service, NMFS)

BCO-DMO Data Manager:

Ms Dicky Allison (Woods Hole Oceanographic Institution, WHOI)

Project:

U.S. GLOBEC Georges Bank (GB)

Data URL:

https://www.bco-dmo.org/dataset-deployment/449332/data

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Description

The MOCNESS is based on the Tucker Trawl principle (Tucker, 1951). The particular MOCNESS system from which these CTD data came is one of three net systems. The MOCNESS-.25 carries nine rectangular nets (1/4-m²), usually with 64 micrometer mesh. In all three MOCNESS systems, the underwater unit sends a data frame, comprised of temperature, depth, conductivity, net-frame angle, flow count, time, number of open net, and net opening/closing, to the deck unit in a compressed hexadecimal format every 2 seconds and from the deck unit to a microcomputer every 4 seconds. Temperature (to approximately 0.01 deg C) and conductivity are measured with SEABIRD sensors. Normally, a modified T.S.K.-flowmeter is used. Both the temperature and conductivity sensors and the flowmeter are mounted on top of the frame so that they face horizontally when the frame is at a towing angle of 45deg. Calculations of salinity (to approximately 0.01 o/oo S), potential temperature (theta), potential density (sigma), the oblique and vertical velocities of the net, and the approximate volume filtered by each net are made after each string of data has been received by the computer. (Wiebe et al., 1985) In addition, data were collected from four other sensors attached to the frame: the Transmissometer, the Fluorometer, the Downwelling light sensor, and the Oxygen sensor. A SeaBird underwater pump was also included in the sensor suite.

It should be noted that whenever the data are of questionable value, 50.000 is written in the particular data field.

Unless otherwise indicated, these data have not been post-processed.

For additional information, contact the chief scientist for the cruise or the U.S. GLOBEC Data Management Office (DMO).

Note: Some variables have been eliminated from the display but are nevertheless available. These variables include: oxycurrent, oxytemp, tempco, and echo.

References

Fofonoff and Millard, 1983, UNESCO technical papers in Marine Sciences, #44.

Tucker, G.H., 1951. Relation of fishes and other organisms to the scattering of underwater sound. Journal of Marine Research, 10: 215-238.

Wiebe, P.H., K.H. Burt, S. H. Boyd, A.W. Morton, 1976. The multiple opening/closing net and environmental sensing system for sampling zooplankton. Journal of Marine Research, 34(3): 313-326.

Wiebe, P.H., A.W. Morton, A.M. Bradley, R.H. Backus, J.E. Craddock, V. Barber, T.J. Cowles and G.R. Flierl, 1985. New developments in the MOCNESS, an apparatus for sampling zooplankton and micronekton. Marine Biology, 87: 313-323.

updated September 30, 2008. mda

Methods & Sampling

Dataset acquisition description

The underwater unit sends a data frame, comprised of temperature, depth, conductivity, net-frame angle, flow count, time, number of open net, and net opening/closing, to the deck unit in a compressed hexadecimal format every 2 seconds and from the deck unit to a microcomputer every 4 seconds... Temperature (to approximately 0.01 deg C) and conductivity are measured with SEABIRD sensors. Normally, a modified T.S.K.-flowmeter is used... Both the temperature and conductivity sensors and the flowmeter are mounted on top of the frame so that they face horizontally when the frame is at a towing angle of 45deg... Calculations of salinity (to approximately 0.01 o/oo S), potential temperature (theta), potential density (sigma), the oblique and vertical velocities of the net, and the approximate volume filtered by each net are made after each string of data has been received by the computer.

Deployment-specific acquisition description

Data Processing Description

Dataset Processing Description

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

CTD MOCNESS

Supplied Description:

Instrument Type

Generic Name: CTD MOCNESS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/131/

Generic Description:

The CTD part of the MOCNESS includes 1) a pressure (depth) sensor which is a thermally isolated titanium strain gauge with a standard range of 0-5000 decibars full scale, 2) A Sea Bird temperature sensor whose frequency output is measured and sent to the surface for logging and conversion to temperature by the software in the MOCNESS computer (The system allows better than 1 milli-degree resolution at 10 Hz sampling rate), and 3) A Sea Bird conductivity sensor whose output frequency is measured and sent to the surface for logging and conversion to conductivity by the software in the computer (The system allows better than 1 micro mho/cm at 10 Hz sampling rate). The data rate depends on the speed of the computer and the quality of the cable. With a good cable, the system can operate at 2400 baud, sampling all variables at 2 times per second. One sample every 4 seconds is the default, although the hardware can operate much faster. (From The MOCNESS Manual)

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
cruiseid	Cruise identification, e.g. EN261, for Endeavor cr. 261	none	cruiseid
year	Four digit year		year
brief_desc	Brief cruise description, such as: broad-scale, process, mooring, etc.,		brief_desc
tow	Tow number		tow
day_local	Day of month, local time, 1 - 31		day_local
month_local	Month of year, local time 1 - 12		month_local
station	station number, from event log		station
station_std	standard station number, from event log		station_std
yrday_local	year day, Julian Calendar local time. January 1 = yrday 1	decimal day	yrday_local
potemp	potential temperature (International Practical Temperature Scale - 68 ,or 90. When known, the scale will be reported in the units field of the documentation file.	degrees C	potemp
sal	salinity, calculated from the CTD 'primary sensors' of conductivity and temperature, Practical Salinity Scale, dimensionless.1 Depending on the input source, salinity from the primary sensors can have a variety of names i.e. s0, s00, s1, sal0, sal00, sal1. Change to DMO term sal.	unitless	sal
sigma_0	potential density at the surface	kg/m3-1000	sigma_0
flvolt	fluorescence (0-5 volts)	volts	flvolt
angle	angle of net frame relative to vertical (0-89degrees)	degrees	tow_angle
flow	consecutive flow counts	counts	flow
hzvel	horizontal net velocity	meters/minute	hzvel
vtvel	vertical net velocity	meters/minute	vtvel
vol_net	volume filtered	cubic meters	vol_filt
trans_v	light transmission (0-5 volts)	volts	trans_v
net	sequential MOCNESS net number		net
lat	latitude, negative = South	decimal degrees	lat
press	depth of sample	decibars	press
lon	longitude, negative = West	decimal degrees	lon
time_local	time of day; local time using 24 hour clock.	HHmm.m	time_local

Database

Contribute Data

Dataset: CTD_MOCNESS.25
Deployment: AL9403II

References

Dataset acquisition description

Deployment-specific acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: CTD_MOCNESS.25Deployment: AL9403II

References

Dataset acquisition description

Deployment-specific acquisition description

Dataset Processing Description

Dataset: CTD_MOCNESS.25
Deployment: AL9403II