Dataset: GP16 CTD - GT-C UpCasts

Name: GTC CTD up casts along the US GEOTRACES East Pacific Zonal Transect from the R/V Thomas G. Thompson TN303 cruise in the tropical Pacific from Peru to Tahiti during 2013 (U.S. GEOTRACES EPZT project)
Published: 2014-10-30
Keywords: oceans

Cite This Dataset

Spatial Extent: N:-10.2502 E:-77.3761 S:-16.0006 W:-152.0004

Project:

U.S. GEOTRACES East Pacific Zonal Transect (GP16) (U.S. GEOTRACES EPZT)

Program:

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

Lead Principal Investigator:

James W. Moffett (University of Southern California, USC-HIMS)

Co-Principal Investigator:

Gregory A. Cutter (Old Dominion University, ODU)

Christopher R. German (Woods Hole Oceanographic Institution, WHOI)

Contact:

James W. Moffett (University of Southern California, USC-HIMS)

BCO-DMO Data Manager:

Stephen R. Gegg (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

30 October 2014

Version Date:

2014-10-30

Restricted:

Validated:

Yes

Current State:

Final no updates expected

GTC CTD up casts along the US GEOTRACES East Pacific Zonal Transect from the R/V Thomas G. Thompson TN303 cruise in the tropical Pacific from Peru to Tahiti during 2013 (U.S. GEOTRACES EPZT project)

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Description

CTD - GT-C UpCasts 20141030ODU

SMDEPTH IS SAUNDERS-MANTYLA DEPTH (INTEGRATED; USES DYNAMIC HEIGHT)
FMDEPTH IS FOFONOFF-MILLARD DEPTH (NON-INTEGRATED; ALSO USED BY SBE)

Methods & Sampling

From the TN303 cruise report:
Two types of rosette/SBE9plus CTD casts (ODF/30L-Niskin and GT-C/12L-GoFlo) were made at 36 station locations during U.S. GEOTRACES EPZT.

Shipboard CTD data processing was performed automatically at the end of each deployment using SIO/STS CTD processing software v.5.1.6-1. Raw GT-C CTD data and bottle trip files, acquired by SBE Seasave V 7.17a on a Windows XP workstation, were also imported into the Linux processing system, providing a backup of the raw data.

At the end of the cruise, all GT-C CTD data were updated in the database using the post-cast Seasave-processed ".btl" file 5-second averaged CTD data, in order to include processed CTD Oxygen values. The 5-second average used resulted in slightly better agreement between CTD and GoFlo salinity values than the shorter 3-second average used for the Niskin rosette.

Data Processing Description

Processing notes from README provided by ODF:
The CTD depths in the shipboard version (20 Dec 2013) of the data - bottle data in particular - were originally calculated incorrectly due to two software errors. A small error in the gravity calculation affected both bottle and CTD data. In addition, the bottle file CTDDEPTH calculation was inadvertently using a combination of latitude and longitude, vs just latitude, as input to the gravity component of the depth equation, causing up to a 20m error in some of the casts.

Two different depth calculations were subsequently added into these data files: the original, integrated Saunders-Mantyla integrated depth calculations (SMDEPTH), with the gravity error corrected; and the non-integrated Fofonoff-Millard depth calculations (FMDEPTH), same as those used by SBE. The Fofonoff-Millard depths are used for the primary CTDDEPTH column in both bottle data files.

ODF reports that the CTDDEPTH column agreed best with depths identified from CTD bottle trips recorded during GEOTRACES CTD acquisition. The depth values in CTDDEPTH column are from the Saunders & Fofonoff 1976 calculation of depth from pressure. This is the same default calculation of depth used by SeaBird (SBE) software. GEOTRACES CTD data acquisition uses SBE software. It follows that it would be preferable and consistent for GEOTRACES and ODF to use the values in the CTDDEPTH column.

Processing notes from README_1410.txt:
Separate columns of S-M and F-M depths ("SMDEPTH" and "FMDEPTH") are included in bottle and CTD files. In addition, "ODF_CTDPRS" is an added column in the bottle files. This may differ from the main CTDPRS in the bottle file only for EPZT GT-C casts, where Seasave-processed CTD trip data were used.

Note: 'FLAG_W' columns = WHP (WOCE Hydrographic Program) quality flags. ODF used the WHP quality coding schema, but also included two non-standard quality codes in the GT-C bottle file:
- QUALITY CODE 'A' WAS USED FOR DATA VALUES SUBMITTED AS 'ABOVE DETECTION LIMITS'
- QUALITY CODE 'B' WAS USED FOR DATA VALUES SUBMITTED AS 'BELOW DETECTION LIMITS'
This was at the request of two different PIs.

Data Files

File
GT-C_UpCasts_v30Oct2014.csv (Comma Separated Values (.csv), 28.27 MB) MD5:76b0ec910c11944cfaad507ac62ad67b Primary data file for dataset ID 522658

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1130870
NSF Division of Ocean Sciences	OCE-1235248

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
TN303	GP16 GEOTRACES EPZT GEOTRACES East Pacific Zonal Transect (EPZT) GT13 325020131025	2013-10-25	R/V Thomas G. Thompson	James W. Moffett (Chief Scientist) Gregory A. Cutter (Co-Chief Scientist) Christopher R. German (Co-Chief Scientist)	data info

Instruments

CTD Sea-Bird SBE 911plus

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: CTD Sea-Bird SBE 911plus

Acronym: CTD SBE 911plus

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0058/

Generic Description:

The Sea-Bird SBE 911 plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911 plus 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 9 plus and SBE 11 plus is called a SBE 911 plus. The SBE 9 plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3 plus and SBE 4). The SBE 9 plus 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

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

Supplied Name	Supplied description	Supplied Units	Standard Name
DATASET_ID	CTD Dataset Identifier	text	dataset_id
EXPOCODE	expedition code assigned by the CCHDO: NODCShipCodeYearMonthDay	text	cruise_name
SECT_ID	cruise section identification number	text	cruise_name
GEOTRC_EVENTNO	GEOTRACES Event Number	dimensionless	event
STNNBR	Station Number	dimensionless	station
CASTNO	Cast Number	dimensionless	cast
DATE	Station Date (GMT)	YYYYMMDD	date
TIME	Station Time (GMT)	HHMM	time
LATITUDE	Station Latitude (South is negative)	decimal degrees	lat
LONGITUDE	Station Longitude (West is negative)	decimal degrees	lon
BTMDEPTH	Multibeam bottom depth of the cast	meters	depth_w
INSTRUMENT_ID	Instrument Id (from CTD profile data headers)	dimensionless	instrument
CTDPRS	CTD Pressure	DBARS	press
CTDPRS_FLAG_W	CTD pressure quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
CTDTMP	CTD Temperature; ITS-90	degrees celsius	temp
CTDTMP_FLAG_W	CTD temperature quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
CTDSAL	CTD Salinity	PSS-78	sal
CTDSAL_FLAG_W	CTD salinity quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
CTDOXY	CTD Oxygen	UMOL/KG	O2
CTDOXY_FLAG_W	CTD oxygen quality flag(see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
TRANSM	Light Transmission (0-5VDC)	volts	trans_v
TRANSM_FLAG_W	Light Transmission quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
FLUORM	Fluorescence (0-5VDC)	volts	fluor
FLUORM_FLAG_W	Fluorescence quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
TURBDTY	Turbidity (0-5VDC)	volts	turbid_v
TURBDTY_FLAG_W	Turbidity quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
SMDEPTH	SMDEPTH IS SAUNDERS-MANTYLA DEPTH (INTEGRATED; USES DYNAMIC HEIGHT)	METERS	depth
SMDEPTH_FLAG_W	SMDepth quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
F_M_DEPTH	FMDEPTH IS FOFONOFF-MILLARD DEPTH (NON-INTEGRATED; ALSO USED BY SBE)	METERS	depth
FMDEPTH_FLAG_W	FMDepth quality flag (see WOCE Hydrographic Program Quality Flags)	dimensionless	flag
CTDNOBS	CTD Number of Observations	dimensionless	numb_obs
CTDETIME	CTD Elapsed Time	SECONDS	time_elapsed
ISO_DATE_TIME	Date/Time (ISO formatted)	YYYY-MM-DDTHH:MM:SS[.xx]Z	ISO_DateTime_UTC

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Database

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Dataset: GP16 CTD - GT-C UpCasts