Dataset: CTD_MOCNESS_1_10
Deployment: NBP1002

CTD data collected during MOCNESS tows with both 1m2 and 10m2 mouth openings

Principal Investigator:

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

BCO-DMO Data Manager:

Ms Dicky Allison (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Possible climate-induced change in the distribution of Pleuragramma antarcticum on the Western Antarctic Peninsula Shelf (Antarctic_micronek)

Current State:

Final with updates expected

Version:

final

Version Date:

2017-11-14

Data URL:

https://osprey.bco-dmo.org/dataset-deployment/719252/data

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Description

CTD observations taken simultaneously during MOCNESS tows,

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)

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.

Methods & Sampling

Dataset acquisition 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 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)

Data Processing Description

Dataset 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.

More information about this dataset deployment

Funding

Award Number	Funding Source
ANT-0741348	NSF Antarctic Sciences

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

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
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
yrday_local	year day as a decimal, based on Julian calendar, local; includes time due to precision	YYY.Yyyyyy	yrday_local
time_local	time, local using 24 hour clock to decimal minutes	HHmm.m	time_local
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
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
net	MOCNESS net number, (00-08)		net
lat	latitude, negative = South	DD.D	lat
lon	longitude, negative = West	DDD.D	lon

Database

Contribute Data

Dataset: CTD_MOCNESS_1_10
Deployment: NBP1002

CTD observations taken simultaneously during MOCNESS tows,

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: CTD_MOCNESS_1_10Deployment: NBP1002

CTD observations taken simultaneously during MOCNESS tows,

Dataset acquisition description

Dataset Processing Description

Dataset: CTD_MOCNESS_1_10
Deployment: NBP1002