Dataset: CTD_MOCNESS1

Name: CTD data collected during MOCNESS hauls from ARSV Laurence M. Gould, RVIB Nathaniel B. Palmer LMG0104, LMG0106, LMG0203, NBP0103, NBP0104, NBP0202, NBP0204 in the Southern Ocean from 2001-2002 (SOGLOBEC project)
Published: 2001-12-03
Keywords: oceans

Cite This Dataset

Spatial Extent: N:33.064 E:-64.1496 S:-69.7085 W:-77.0803

Project:

U.S. GLOBEC Southern Ocean (SOGLOBEC)

Program:

U.S. GLOBal ocean ECosystems dynamics (U.S. GLOBEC)

Principal Investigator:

Daniel P. Costa (University of California-San Diego, UCSD)

Dr Joseph J. Torres (University of South Florida, USF)

Peter H. Wiebe (Woods Hole Oceanographic Institution, WHOI)

Technician:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI)

Version:

final

Version Date:

2001-12-03

Validated:

Yes

Current State:

Final no updates expected

CTD data collected during MOCNESS hauls from ARSV Laurence M. Gould, RVIB Nathaniel B. Palmer LMG0104, LMG0106, LMG0203, NBP0103, NBP0104, NBP0202, NBP0204 in the Southern Ocean from 2001-2002 (SOGLOBEC project)

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Description

CTD observations taken simultaneously during MOCNESS tows,
plus MOCNESS sampling conditions

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

The MOCNESS is based on the Tucker Trawl principle (Tucker, 1951). The particular MOCNESS system from which these CTD data came is one of two net systems. The MOCNESS-1 has nine rectangular nets (1m x 1.4 m) which are opened and closed sequentially by commands through conducting cable from the surface (Wiebe et al., 1976). In both 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 flow meter 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 Down welling light sensor, and the Oxygen sensor. A SeaBird underwater pump was also included in the sensor suite.

It should be noted that due to Antarctic cold, the first few minutes of data are often of questionable value as they are extremely variable and have a high frequency of "50.000" (indicating "bad values") in the temp, theta and sal fields. Once the sensors encounter deeper, warmer water, they start recording good values.

For additional information, contact the chief scientist for the cruise.

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.

last updated January 10, 2006; gfh

Methods & Sampling

The MOCNESS is based on the Tucker Trawl principle (Tucker, 1951). The particular MOCNESS system from which these CTD data came is one of two net systems. The MOCNESS-1 has nine rectangular nets (1m x 1.4 m) which are opened and closed sequentially by commands through conducting cable from the surface (Wiebe et al., 1976). The MOCNESS-10 (with 10 m2 nets)carries 6 nets of 3.0-mm circular mesh. In both 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 flow meter 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 Down welling light sensor, and the Oxygen sensor. A SeaBird underwater pump was also included in the sensor suite.

Data Processing Description

It should be noted that due to Antarctic cold, the first few minutes of data are often of questionable value as they are extremely variable and have a high frequency of '50.000' (indicating 'bad values') in the temp, theta and sal fields. Once the sensors encounter deeper, warmer water, they start recording good values.

For additional information, contact the chief scientist for the cruise.

Data Files

File
mocness_ctd.csv (Comma Separated Values (.csv), 35.95 MB) MD5:dff00f9e9c27ef6719520efb67eb25fe Primary data file for dataset ID 2515

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Antarctic Sciences	unknown SOGLOBEC NSF ANT

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
LMG0104	GLOBECI	2001-04-20	ARSV Laurence M. Gould	Dr Joseph J. Torres (Chief Scientist)	data info
LMG0106		2001-07-21	ARSV Laurence M. Gould	Daniel P. Costa (Chief Scientist)	data info
LMG0203	GLOBECIII	2002-04-07	ARSV Laurence M. Gould	Dr Joseph J. Torres (Chief Scientist)	data info
NBP0103	GLOBECI	2001-04-24	RVIB Nathaniel B. Palmer	Peter H. Wiebe (Chief Scientist)	data info
NBP0104	GLOBECII	2001-07-22	RVIB Nathaniel B. Palmer	Peter H. Wiebe (Chief Scientist)	data info
NBP0202	GLOBECIII	2002-04-09	RVIB Nathaniel B. Palmer	Peter H. Wiebe (Chief Scientist)	data info
NBP0204	GLOBECIV	2002-07-31	RVIB Nathaniel B. Palmer	Peter H. Wiebe (Chief Scientist)	data info

Instruments

CTD - profiler

Supplied Name: Conductivity, Temperature, Depth

Supplied Description:

Instrument Type

Generic Name: CTD - profiler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/130/

Generic Description:

The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.

This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934.

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

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
cruiseid	cruise identification, e.g. NBP0202, for RVIB Palmer cruise 0202		cruiseid
temp	temperature of water	degrees C	temp
datatype	sampling method - instrument type, e.g. MOCNESS-1 or MOCNESS-10		datatype
year	year		year
brief_desc	brief cruise description, such as process or mooring		brief_desc
tow	tow number		tow
day_gmt	day of month, GMT, 1-31		day_gmt
month_gmt	month of year, GMT, 1 - 12		month_gmt
station	station number, from event log		station
station_std	standard station number, from event log		station_std
yrday_gmt	year day as a decimal, based on Julian calendar, GMT	YYY.Y	yrday_gmt
time_gmt	time, GMT using 24 hour clock to decimal minutes	HHmm.m	time_gmt
press	depth of observation or sample	meters	press
potemp	potential temperature or theta¹ ¹Fofonoff and Millard, 1983, UNESCO technical papers in Marine Sciences, #44		potemp
sal	salinity calculated from conductivity, bad values are set to 50		sal
sigma_0	potential density¹ ¹Fofonoff and Millard, 1983, UNESCO technical papers in Marine Sciences, #44		sigma_0
flvolt	relative fluorescence (0-5 volts)	volts	flvolt
angle	angle of net frame relative to vertical (0-89 degrees)	degrees	tow_angle
flow	consecutive flow counts		flow
hzvel	horizontal net velocity	m/min	hzvel
vtvel	vertical net velocity	m/min	vtvel
vol_filt	volume filtered	meters<sup>3</sup>	vol_filt
trans_v	transmissometry or light transmission, (0-5 volts)	volts	trans_v
o2	dissolved oxygen	ml/liter	O2
lite	downwelling light	volts	no_bcodmo_term
net	MOCNESS net number, (00-08)		net
lat	latitude, negative = South	DD.D	lat
lon	longitude, negative = West	DDD.D	lon