Dataset: GP15 CTD GTC

Name: CTD data from the GTC rosette on the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) from September to November 2018
Published: 2020-07-22
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.778332.2

Spatial Extent: N:56.0583 E:-151.9937 S:-19.9999 W:-156.9622

Temporal Extent: 2018-09-24 - 2018-11-22

Project:

US GEOTRACES Pacific Meridional Transect (GP15) (U.S. GEOTRACES PMT)

Program:

U.S. GEOTRACES (U.S. GEOTRACES)

Principal Investigator:

Gregory A. Cutter (Old Dominion University, ODU)

Co-Principal Investigator:

Karen L. Casciotti (Stanford University)

Phoebe J. Lam (University of California-Santa Cruz, UCSC)

Contact:

Karen L. Casciotti (Stanford University)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2020-07-22

Restricted:

Validated:

Yes

Current State:

Final no updates expected

CTD data from the GTC rosette on the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) from September to November 2018

Abstract:

CTD data from the GTC rosette on the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) from September to November 2018.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2020-07-22	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.778332.2	2020-08-05

Methods & Sampling

The description below is excerpted from the GP15 Cruise Report (PDF). Refer to cruise report for more information, including the complete problem report and CTD processing details.

The Cutter (ODU) group provided the GEOTRACES Trace Element Carousel sampling system (GTC), including the Dynacon winch with 7300 m of Vectran cable with conductors, clean lab, and Seabird carousel/CTD with 24 12L GO-FLO bottles (and 11 spares). In total, 72 GTC hydrocasts were conducted and 2 GO-FLOs per depth were triggered (3 per depth for super stations to accommodate water requests), with subsequent filtration using Acropak capsules (0.2 um). An average of 10 sample bottles were filled from each Acropakfiltered GO-FLO, but this number varied based on station type and depth. For the 35 stations occupied on Leg 1 and Leg 2, which includes shelf, slope, demi, full, super, and "bonus" stations between 56°N and 20°S, this represented the acquisition of upwards of 15,500 trace element samples.

The CTD data acquisition system consisted of an SBE-11+ (V2) deck unit and a networked generic PC workstation running Windows 7. SBE SeaSave7 v.7.26.1.8 software was used for data acquisition and to close bottles on the rosette.

Data Processing Description

The description below is excerpted from the GP15 Cruise Report (PDF). Refer to cruise report for more information, including the complete problem report and CTD processing details.

Shipboard CTD data processing was performed after deployment using SIO/ODF python CTD processing software v. 0.3. CTD acquisition data were copied onto a OS X system, and then processed. CTD data at bottle trips were extracted, and a 2-decibar down-cast pressure series created. A number of issues were encountered during GP15 ODF that directly impacted CTD analysis. Issues that directly impacted bottle closures, such as slipping guide rings, were detailed in the Underwater Sampling Package section of the ODF report.

Plots of CTD casts are attached as Supplemental File, "GTC_CTD_Plots.zip".

_FLAG_W columns follow the WOCE Hydrographic Program (WHP) quality flag definitions.

The WHP quality codes for the water bottle itself are:
1 = Bottle information unavailable.
2 = No problems noted.
3 = Leaking.
4 = Did not trip correctly.
5 = Not reported.
6 = Significant discrepancy in measured values between Gerard and Niskin bottles.
7 = Unknown problem.
8 = Pair did not trip correctly. Note that the Niskin bottle can trip at an unplanned depth while the Gerard trips correctly and vice versa.
9 = Samples not drawn from this bottle.
(Flags 6, 7, and 8 apply primarily to large volume samplers.)

The WHP bottle parameter data quality codes are:
1 = Sample for this measurement was drawn from water bottle but analysis not received. Note that if water is drawn for any measurement from a water bottle, the quality flag for that parameter must be set equal to 1 initially to ensure that all water samples are accounted for.
2 = Acceptable measurement.
3 = Questionable measurement.
4 = Bad measurement.
5 = Not reported.
6 = Mean of replicate measurements (Number of replicates should be specified).
7 = Manual chromatographic peak measurement.
8 = Irregular digital chromatographic peak integration.
9 = Sample not drawn for this measurement from this bottle.

The WHP CTD data quality codes are:
1 = Not calibrated.
2 = Acceptable measurement.
3 = Questionable measurement.
4 = Bad measurement.
5 = Not reported.
6 = Interpolated over >2 dbar interval.
7 = Despiked.
8 = Not assigned for CTD data.
9 = Not sampled.

BCO-DMO Processing:
- parsed file headers to obtain STNNBR, CASTNO, DATE, TIME, LATITUDE, LONGITUDE, and DEPTH;
- concatenated data files for separate casts into one dataset;
- 2020-07-22: joined to GP15 event log to obtain EVENTNO (matching values on STNNBR + CASTNO); added ISO8601 date/time format.

Data Files

File
GP15_CTD_GTC.csv (Comma Separated Values (.csv), 13.77 MB) MD5:9a57302b08adf45e3a958b94c24b605a Primary data file for dataset ID 778332

Supplemental Files

File
GEOTRACES GP15 GTC CTD Plots filename: GTC_CTD_Plots.zip (ZIP Archive (ZIP), 102.81 MB) MD5:0427c30bc1ee36a76946854573aa26db CTD plots (jpg and pdf formats) from GTC rosette casts on the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15) from September to November 2018.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1657781
NSF Division of Ocean Sciences	OCE-1657944
NSF Division of Ocean Sciences	OCE-1658318

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
RR1814	GP15 GP15 Leg1 33RR20180918 PMT US GEOTRACES PMT	2018-09-18	R/V Roger Revelle	Gregory A. Cutter (Chief Scientist) Karen L. Casciotti (Co-Chief Scientist) Phoebe J. Lam (Co-Chief Scientist)	data info
RR1815	GP15 GP15 Leg 2 33RR20180918 PMT US GEOTRACES PMT	2018-10-24	R/V Roger Revelle	Gregory A. Cutter (Chief Scientist) Karen L. Casciotti (Co-Chief Scientist) Phoebe J. Lam (Co-Chief Scientist)	data info

Instruments

CTD Sea-Bird

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: CTD Sea-Bird

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

Generic Description:

Conductivity, Temperature, Depth (CTD) sensor package from SeaBird Electronics, no specific unit identified. This instrument designation is used when specific make and model are not known. See also other SeaBird instruments listed under CTD. More information from Sea-Bird Electronics.

GO-FLO Bottle

Supplied Name:

Supplied Description:

Seabird carousel/CTD with 24 12L GO-FLO bottles (and 11 spares)

Instrument Type

Generic Name: GO-FLO Bottle

Acronym: GO-FLO

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/30/

Generic Description:

GO-FLO bottle cast used to collect water samples for pigment, nutrient, plankton, etc. The GO-FLO sampling bottle is specially designed to avoid sample contamination at the surface, internal spring contamination, loss of sample on deck (internal seals), and exchange of water from different depths.

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
EXPOCODE	Expedition code	unitless	EXPOCODE
SECT_ID	Section ID	unitless	cruise_name
INSTRUMENT_ID	Instrument ID number from CTD file header	unitless	instrument
EVENTNO	Event number; obtained from the cruise event log	unitless	event
STNNBR	Station number; from CTD file header	unitless	station
CASTNO	Cast Identifier; from CTD file header	unitless	cast
DATE	Date from CTD file header; format: yyyymmdd	unitless	date
TIME	Time from CTD file header; format: HHMM	unitless	time
LATITUDE	Latitude from CTD file header; positive values = North	decimal degrees	lat
LONGITUDE	Longitude from CTD file header; positive values = East	decimal degrees	lon
DEPTH	Bottom depth; from CTD file header	meters (m)	depth_w
Event_Descrip	Event description; obtained from the cruise event log	unitless	ev_type
CTDPRS	Sample/sensor pressure	decibars	press
CTDPRS_FLAG_W	WHP quality flag for CTDPRS	unitless	q_flag
CTDTMP	Temperature from CTD sensor in the ITS-90 convention	degrees Celsius	temp
CTDTMP_FLAG_W	WHP quality flag for CTDTMP	unitless	q_flag
CTDSAL	Practical salinity from CTD sensor on the PSS-1978 scale	psu	sal
CTDSAL_FLAG_W	WHP quality flag for CTDSAL	unitless	q_flag
CTDOXY	Concentration of dissolved oxygen from sensor on CTD	micromoles per kilogram (umol/kg)	O2
CTDOXY_FLAG_W	WHP quality flag for CTDOXY	unitless	q_flag
CTDXMISS	Transmissometer	volts	trans_v
CTDXMISS_FLAG_W	WHP quality flag for CTDXMISS	unitless	q_flag
CTDFLUOR	Fluorescence from CTD sensor	volts	fluor
CTDFLUOR_FLAG_W	WHP quality flag for CTDFLUOR	unitless	q_flag
CTDRINKO	Voltage from RINKO dissolved oxygen sensor	volts	O2_v
CTDRINKO_FLAG_W	WHP quality flag for CTDRINKO	unitless	q_flag
ISO_DateTime_UTC	Date and time (UTC) formatted to ISO8601 standard: YYYY-MM-DDThh:mmZ	unitless	ISO_DateTime_UTC

Status message

Database

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Dataset: GP15 CTD GTC