URLhttps://www.bco-dmo.org/dataset/567399
Download URLhttps://www.bco-dmo.org/dataset/567399/data/download
Media Type text/tab-separated-values
Created September 18, 2015
Modified August 19, 2016
State Final no updates expected
Brief Description

CTD data from KN223 in the western North Atlantic.

Acquisition Description

CTD Hydrocasts were performed with a Sea-Bird SBE 911/917 plus CTD mounted near the base of a Niskin 24 Bottle Rosette. The CTD instrumentation included Conductivity (S/N 2147 & 2768), Temperature (ITS-90, S/N 4195 & 4252), Pressure (S/N 63505 SBE090462), Oxygen (SBE 43, S/N 0264), Fluorescence (Wetlab ECO-AFL/FL, S/N FLNTURTD-304), and Beam Transmission (Chelsea/Seatech/Wetlab CStar, S/N CST-1118DR).  Processing firmware is SBE11plus v 5.

At each station, a hydrocast was conducted with a rosette carrying 24 10-L Niskin bottles. The rosette was instrumented with sensors for conductivity, temperature, pressure, oxygen, fluorescence, and beam transmission, as listed above. The downcast was conducted at 30 m per minute in the upper 100 m and increased to 60 m per minute to a maximum depth of ~5 m above the seafloor (based on altimeter data). Features were selected from the downcast data for sampling on the upcast. These features included oxygen minimum layer(s), chlorophyll maximum layer(s), and the thermocline. In addition, standard depths of bottom, 50 m above bottom, 5000 m, 4000 m, 3000 m, 2000 m, 1500 m, 1000 m, 300 m, 200 m, 100 m, 50 m, 10 m, and surface were sampled.

The vent plugs were removed and replaced with t-fittings. A ring of plastic tubing (1/4″ inner diameter) was used to construct a manifold to deliver pressure to each Niskin bottle. Each bottle was connected individually to the manifold to prevent any potential mixing between bottles. The compressor was connected to the initial t-valve in the series and the final t-valve was plugged. The compressor was set to 8 – 10 psi.

Cylindrical, 0.2 um retention membrane filters (Sterivex) were attached to the petcock valve of the Niskin bottles with 1/4″ tubing (Fig. 8). The valves were opened and the water was pushed through the filters with the compressed air. The filtration rate is ~200 mL per minute. When the water stopped dripping through the filter, the filters were removed, capped at both ends, placed into freezer boxes and stored at -70 degrees C in the main lab freezer.

Processing Description

The CTD data were processed with Seasave v. 7.21k.

BCO-DMO Processing:
– Modified parameter names to conform with BCO-DMO naming conventions;
– Obtained lat_start, lon_start, date_start, and time_start from the CTD file headers;
– Converted lat and lon to decimal degrees;
– Added ISO_DateTime_Start column.

Instruments

Instance Description

CTD Hydrocasts were performed with a Sea-Bird SBE 911/917 plus CTD mounted near the base of a Niskin 24 Bottle Rosette.

The Sea-Bird SBE 911plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911plus includes the SBE 9plus Underwater Unit and the SBE 11plus Deck Unit (for real-time readout using conductive wire) for deployment from a vessel. The combination of the SBE 9plus and SBE 11plus is called a SBE 911plus. The SBE 9plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3plus and SBE 4). The SBE 9plus CTD can be configured with up to eight auxiliary sensors to measure other parameters including dissolved oxygen, pH, turbidity, fluorescence, light (PAR), light transmission, etc.). more information from Sea-Bird Electronics

Parameters

cruise_id [cruise_id]
Details
cruise_id
Cruise identification number.
cruise designation; name
cast [cast]
Details
cast

Cast number.

cast or profile number

date_start [date_start]
Details
date_start
Date (YYYYmmdd) at start of cast.

date sampling starts such as YYYYMMDD

time_start [time_start]
Details
time_start
Time (HH:MM:SS) at start of cast.

starting time of observation, GMT time, 24 hour clock

ISO_DateTime_Start [ISO_DateTime_UTC]
Details
ISO_DateTime_Start
Date and time at start of cast, formatted to ISO8601 standard.

Date/Time (UTC) ISO formatted
This standard is based on ISO 8601:2004(E) and takes on any of the following forms:
2009-08-30T09:05:00[.xx] (local time)
2009-08-30T14:05:00[.xx]Z (UTC time)
2009-08-30T14:05:00[.xx]-05:00
The dashes and the colons can be dropped.
The T can also be dropped "by mutual agreement", but one needs the trailing Z if the time is UTC.

Sample ISO_datetime_utc:
2009-08-30T14:05:00[.xx]Z (UTC time)

Format: YYYY-mm-ddTHH:MM:SS[.xx]Z (UTC time)
press [pressure]
Details
press

Pressure. Originally named 'PrDM'.

water pressure at measurement; depth reported as pressure; positive number increasing with water depth
temp [temperature]
Details
temp
Temperature, ITS-90 (primary). Originally named 'T090C'.
water temperature at measurement depth
temp2 [temp2]
Details
temp2
Temperature, ITS-90 (secondary). Originally named 'T190C'.
temperature, as observed by a CTD unit, 'secondary sensor', may be ITS 68 or 90 scale; When known, the temperature scale is reported in the units field of the doc file in degrees Celsius. Depending on the input source the temperature from the secondary sensor can have a variety of names i.e. t1, t2, temp1, temp2, temp_S. Change to DMO term temp2
cond [conductivity]
Details
cond
Conductivity (primary). Originally named 'C0S/m'.

Conductivity.  Units and collection methods may vary.  Often reported in Siemens/meter.

When used in a JGOFS/GLOBEC project this is the conductivity in Siemens/meter for the primary conductivity sensor on a CTD.

cond2 [cond2]
Details
cond2
Conductivity (secondary). Originally named 'C1S/m'.

conductivity, from the CTD 'secondary sensor', usually reported in Siemens/meter. Depending on input source may have a variety of names.

O2_volt [O2_v]
Details
O2_volt
Raw oxygen voltage from SBE43. Originally named 'Sbeox0V'.
Oxygen voltage
Details
O2
Oxygen from SBE43. Originally named 'Sbeox0ML/L'.

dissolved oxygen concentration

fluor [fluorescence]
Details
fluor
Fluorescence from Wetlab ECO-AFL/FL. Originally named 'FlECO-AFL'.

Fluorescence. Indirect measure of pigment concentration.

Units and collection method may vary. Units often reported in milligrams/meter^3 (mg/m3) or micromoles per liter (ug/L). Sometimes reported after being calibrated against extracted pigment concentrations.

In JGOFS/GLOBEC projects fluorescence is measured from CTD instrument sensor.

beam_att [unknown]
Details
beam_att
Beam attenuation from WET Labs C-Star. Originally named 'CStarAt0'.
association with a community-wide standard parameter is not yet defined
beam_trans [transmission]
Details
beam_trans
Beam transmission from WET Labs C-Star. Originally named 'CStarTr0'.

light transmission, as percent

turbidity [turbidity]
Details
turbidity
Turbidity from WET Labs ECO. Originially named 'TurbWETntu0'.

Turbidity is the cloudiness or haziness of a fluid caused by individual particles

depth [depth]
Details
depth

Depth. Originally named 'DepSM'.

Observation/sample depth below the sea surface. Units often reported as: meters, feet.


When used in a JGOFS/GLOBEC dataset the depth is a best estimate; usually but not always calculated from pressure; calculated either from CTD pressure using Fofonoff and Millard (1982; UNESCO Tech Paper #44) algorithm adjusted for 1980 equation of state for seawater (EOS80) or simply equivalent to nominal depth as recorded during sampling if CTD pressure was unavailable.

sal [sal]
Details
sal
Salinity (primary). Originally named 'Sal00'.

salinity, calculated from the CTD 'primary sensors' of conductivity and temperature, Practical Salinity Scale (PSS-78), dimensionless. Depending on the input source, salinity from the primary sensors can have a variety of names i.e. s0, s00, sal0, sal00.

sal2 [sal2]
Details
sal2
Salinity (secondary). Originally named 'Sal11'.
salinity, calculated from the CTD 'secondary sensors' of conductivity and temperature, Practical Salinity Scale, dimensionless. Depending on the input source, salinity from the secondary sensors can have a variety of names including s1, s2, s11, s22, sal1, sal2, sal22, sal_S.
sound_vel [sound_vel]
Details
sound_vel
Sound velocity. Originally named 'SvDM'.

sound velocity in sea water, in meters/second

O2_2 [unknown]
Details
O2_2
Oxygen from SBE43. Originally named 'Sbeox0ML/L'.
association with a community-wide standard parameter is not yet defined
O2_pcnt_sat [O2_sat_pcnt]
Details
O2_pcnt_sat
Oxygen percent saturation from SBE43. Originally named 'Sbeox0PS'.
Saturation of oxygen in the water body, as a percentage.
flag [flag]
Details
flag

Flag.

Data flag. Multiple uses which are dataset dependent. Some uses: data quality, collection occurance or success, depth indicator. See dataset documentation for specific details

Dataset Maintainers

NameAffiliationContact
Steven L. D'HondtUniversity of Rhode Island (URI-GSO)
Robert PockalnyUniversity of Rhode Island (URI-GSO)
Arthur J. SpivackUniversity of Rhode Island (URI-GSO)
Shannon RauchWoods Hole Oceanographic Institution (WHOI BCO-DMO)

BCO-DMO Project Info

Project Title North Atlantic Meridional Circulation during the Last Glacial Maximum: Density Structure and Pre-formed Nitrate: Phase I
Acronym AMOC Last Glacial Max
URLhttps://www.bco-dmo.org/project/567401
Created September 18, 2015
Modified September 18, 2015
Project Description

Description from NSF award abstract:
The large-scale conveyor-belt-like circulation of the Atlantic Ocean (the Atlantic Meridional Overturning Circulation, or AMOC) significantly affects climate via its heat flux and its impact on atmospheric carbon dioxide levels. A number of lines of evidence suggest that the structure of the circulation was different during the last ice age, however these reconstructions are indirect. Sedimentary pore waters in the deep sea preserve ancient seawater, and offer the possibility of more directly documenting how AMOC of the last glacial maximum differed from that of the present.

This project, led by a team of researchers from the University of Rhode Island, will address these fundamental questions about the links between ocean circulation and climate change. Specifically, funding supports a month-long research expedition to collect long sediment cores along a transect between Puerto Rico and New England. Coring sites would range in depth from 1 to more than 5 km. Coring targets will be chosen with a combination of multibeam swath bathymetry, seafloor backscatter, and CHIRP sub-bottom seismic data. The team would analyze the composition (chloride, dissolved oxygen, and nitrate concentrations) of pore waters in the recovered sediments shipboard to detect the relict signal of deep water chemistry during the last glacial maximum. These measurements will allow the researchers to directly test the influence of glacial circulation on climate (via the pre-formed nitrate content of deep and intermediate water in the LGM North Atlantic). The expedition will include several graduate and undergraduate students, offering a valuable training activity and a strong educational experience.

Data Project Maintainers
NameAffiliationRole
Arthur J. SpivackUniversity of Rhode Island (URI-GSO)Principal Investigator
Steven L. D'HondtUniversity of Rhode Island (URI-GSO)Co-Principal Investigator
Robert PockalnyUniversity of Rhode Island (URI-GSO)Co-Principal Investigator
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