Dataset: CTD_MOCNESS1
Deployment: OC473

CTD data collected during 1 meter2 MOCNESS hauls

Principal Investigator:

Gareth Lawson (Woods Hole Oceanographic Institution, WHOI)

Co-Principal Investigator:

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

Project:

Horizontal and Vertical Distribution of Thecosome Pteropods in Relation to Carbonate Chemistry in the Northwest Atlantic and Northeast Pacific (OAPS)

Current State:

Final no updates expected

Version:

08 February 2012

Version Date:

2012-02-08

Data URL:

https://www.bco-dmo.org/dataset-deployment/454918/data

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Description

A standard 1-m2 Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS; Wiebe et al., 1985) was used to collect zooplankton to determine the taxonomic composition of the zooplankton in the study site with a specific focus on the shell bearing thecosomatous pteropods. It was also used to ground truth acoustic data collected with the HTI multi-frequency system and the Edgetech broadband system.

These data are the CTD data collected during the 1 meter2 MOCNESS tows. They provide standard environmental measurements simultaneously with the collection of the animals.

Fluorescence, oxygen and irradiance data were not collected from this instrument system.

Methods & Sampling

Dataset acquisition description

From the MOCNESS Operating Instruction Manual: "The nets are opened and closed sequentially by commands through a single conductor armored cable from the surface. The electronics has 16-bits of resolution and the basic data stream consists of temperature, depth, conductivity, frame angle, flow counts, net number and net response. ;An acquisition/controller computer retrieves data from the underwater unit at a rate of up to 4 times a second. Temperature (to approximately 0.01 deg C) and conductivity are measured with SEABIRD sensors. A modified T.S.K. flowmeter is normally used to measure flow past the net. Both the temperature and salinity sensors and the flowmeter are attached to brackets which are mounted on the top portion of the frame so that they face directly into the flow when the frame is at a towing angle of 45 deg. An electronic pendulum angle transducer measures the angle of the towed net through the water. A GPS unit providing latitude and longitude [is] integrated into the data stream." (p. 7)

Oxygen, fluorescence, and irradiance data were not collected for this dataset.

Deployment-specific acquisition description

A strobe array was attached near the mouth of the net to blind krill and other fast swimming visual plankton, thereby reducing avoidance.

Data Processing Description

Dataset Processing Description

To continue from the MOCNESS Manual:" A microcomputer (together with disk drive and printer) are the deck unit and permit shipboard real-time data acquisition and processing as well as net control. Salinity (to approximately 0.01 ppt), net oblique velocity and vertical velocity, and volume filtered by each net is calculated after each string of data has been received by the computer. Raw and processed data are stored on disc (in separate files) and processed data can be printed out. Plots of net depth versus time, temperature and salinity versus depth, temperature versus salinity and latitude versus longitude are made during a tow and displayed on the computer screen." (p. 7)

See data object ctd_mocness for explicit processing information for each tow.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1041068	NSF Division of Ocean Sciences

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)

Hydroacoustic Technology Incorporated echosounder

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: Hydroacoustic Technology Incorporated echosounder

Acronym: HTI

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

Generic Description:

The Hydroacoustic Technology Inc. (HTI) multi-frequency system is a towed digital split-beam/single-beam hydroacoustic system designed specifically to assess the abundance and distribution of fish and plankton. Digital signal processing hardware is combined with a MS Windows2000/XP -based user interface to produce results in real time. (http://www.htisonar.com/multi_frequency_echo_sounder.htm)

MOCNESS1

Supplied Description:

The MOCNESS was equipped with eight 150-um mesh nets (nets 1-8; borrowed from URI) and one 333-um mesh net (net 0). The underwater unit used was #169. In addition to the standard temperature and conductivity probes the system also had a beta-type strobe-light unit for reducing avoidance of the nets by some zooplankton and possibly small fish. The strobe system has two units each with 12 LED sets (LUXEON Rebel LED) with peak output between 490-520 nm. Seven of the 24 LED sets were no longer working at the start of the sampling. The LEDs are powered by the MOCNESS battery and their pulse width, amplitude, flash rate period, and on/off are controlled by the MOCNESS software. For this cruise the pulse width was 2 ms, the relative amplitude was 99%, and the flash interval was 100 ms.

Instrument Type

Generic Name: MOCNESS1

Acronym: MOC1

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/NETT0097/

Generic Description:

The Multiple Opening/Closing Net and Environmental Sensing System or MOCNESS is a family of net systems based on the Tucker Trawl principle. The MOCNESS-1 carries nine 1-m2 nets usually of 335 micrometer mesh and is intended for use with the macrozooplankton. All nets are black to reduce contrast with the background. A motor/toggle release assembly is mounted on the top portion of the frame and stainless steel cables with swaged fittings are used to attach the net bar to the toggle release. A stepping motor in a pressure compensated case filled with oil turns the escapement crankshaft of the toggle release which sequentially releases the nets to an open then closed position on command from the surface. -- from the MOCNESS Operations Manual (1999 + 2003).

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, 1-31		day_local
month_local	month of year, local, 1 - 12		month_local
station	station number, from event log		station
yrday_local	year day as a decimal, based on Julian calendar, local	YYY.Y	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_MOCNESS1
Deployment: OC473

Dataset acquisition description

Deployment-specific acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: CTD_MOCNESS1Deployment: OC473

Dataset acquisition description

Deployment-specific acquisition description

Dataset Processing Description

Dataset: CTD_MOCNESS1
Deployment: OC473