Dataset: CTD Profiles

Name: Two decibar-averaged CTD profiles from the Hawaii Ocean Time-Series cruises from 1988-2016 (HOT project)
Published: 2018-04-06
Keywords: oceans

Cite This Dataset

DOI:10.1575/1912/bco-dmo.3937.1

Spatial Extent: N:23.4375 E:-157.4567 S:21.2283 W:-158.8575

Temporal Extent: 1988-10-30 - 2016-11-28

Project:

Hawaii Ocean Time-series (HOT): Sustaining ocean ecosystem and climate observations in the North Pacific Subtropical Gyre (HOT)

Program:

Ocean Carbon and Biogeochemistry (OCB)

U.S. Joint Global Ocean Flux Study (U.S. JGOFS)

Ocean Time-series Sites (Ocean Time-series)

Principal Investigator:

David M. Karl (University of Hawaii at Manoa, SOEST)

Contact:

Lance A Fujieki (University of Hawaii at Manoa, SOEST)

BCO-DMO Data Manager:

Mathew Biddle (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2018-04-06

Restricted:

Validated:

Yes

Current State:

Final with updates expected

Data URL:

https://www.bco-dmo.org/dataset/3937/data

Two decibar-averaged CTD profiles from the Hawaii Ocean Time-Series cruises from 1988-2016 (HOT project)

Abstract:

HOT CTD data are collected using a SeaBird CTD 9-11 (9-11 Plus with dual sensors as of HOT-54) at the maximum sampling rate of 24 samples per second (24 Hz). They are screened for errors and processed to 2-dbar averages. The majority of the sampling effort, approximately 60-72 h per standard HOT cruise, is spent at Station ALOHA. High vertical resolution environmental data are collected with a Sea-Bird CTD having external temperature (T), conductivity (C), dissolved oxygen (DO) and fluorescence (F) sensors and an internal pressure (P) sensor. A Sea-Bird 24-place carousel and an aluminum rosette that is capable of supporting 24 12-L PVC bottles are used to obtain water samples from desired depths. The CTD and rosette are deployed on a 3-conductor cable allowing for real-time display of data and for tripping the bottles at specific depths of interest.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2018-04-06	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.1575/1912/bco-dmo.3937.1	2019-07-15

Description

HOT CTD data are collected using a SeaBird CTD 9-11 (9-11 Plus with dual sensors as of HOT-54) at the maximum sampling rate of 24 samples per second (24 Hz). They are screened for errors and processed to 2-dbar averages. Details of the CTD processing for each year can be found in HOT Data Reports #1-8 (see the file Readme.first for information on how to obtain these Data Reports).

CTD data are written to files using formats specified by the WOCE Hydrographic Programme Office. These formats are based on NODC formats, and are detailed in the WHP Office Report WHPO 90-1, available from Steve Diggs, WHPO Data Manager, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0214.

The files contain pressure, temperature and salinity profiles for all casts. Some casts also have dissolved oxygen, light transmission, and fluorescence. The data format consists of a self-documenting header followed by the data. The data records are written so that they can be read with a simple FORTRAN read statement. Details of this format are given in the file Readme.format.

The first year's temperatures are reported in IPTS-68. Subsequent temperatures are reported in ITS-90 units. Since temperature sensor calibrations were done in IPTS-68 units, and the UNESCO routines require IPTS-68 temperature, all intermediate processing was done in IPTS-68. As a final step, temperature and potential temperature were converted to ITS-90 using t_90 = 0.99976 t_68.

Since November 2001 CTD fluorescence data have been regularly calibrated against Chlorophyll bottle data and reported in the CTD files as Chloropigments (CHLPIG) in microgram/liter (uG/L). Bottle Fluorometric Chlorophyll-a plus Pheopigments above 175 dbar are matched against the upcast CTD Fluorometry to calibrate the downcast Fluorescence reported in the CTD files. All CTD files for prior cruises were calibrated and updated to reflect this change.

Starting HOT-177 (2006), the Transmissometer data that used to be included in the CTD files have been replaced by continuous Nitrate measured using Satlantic's InSitu Underwater Spectrometer (ISUS V2). Satlantic's ISUS V2 is a chemical free sensor that uses UV absorption technology to provide accurate nitrate concentration measurements in real-time These data are not included since they were uncalibrated and of questionable quality.

Acquisition Description

HOT CTD yearly reports

Processing Description

Please see HOT's "CTD Data Format Document" for detailed description of original HOT data formatting, original parameter names and Quality Word definitions.

BCO-DMO Processing Notes:

transferred the data from the University of Hawaii ftp site to the BCO-DMO servers.
reformatted the data into csv and appended cruise summary information.
updated the version date in the served data to the date the data was updated.
created EXPOCODE field with by taking the Ship value and replacing the "/" (forward slash) with a "_" (underscore). For example, Ship = 32MW001/1 would have a EXPOCODE = 32MW001_1.
created field (HOT_summary_file_name) which contains the name of the summary file.
created Year, Month, Day fields which were extracted from the Date field.
converted latitude and longitude values to decimal degrees (negative west and south).
created cruise_name field which is extracted from the Ship field. This is composed as the last three values before the "/" in the Ship field value. For example, a value of Ship = 32MW001/1 would have a cruise_name = 001.
created the ISO_DateTime field which is an ISO8601 representation of the date time provided in the data.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-0926766

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
HOT_cruises	Hawaii Ocean Time-series cruises	1988-10-31	Unknown Platform	David M. Karl (Principal Investigator) Robert R. Bidigare (Co-Principal Investigator) Roger Lukas (Co-Principal Investigator) Theresa McKee (BCO-DMO Data Manager)	data info

Instruments

CTD Sea-Bird 911

Supplied Name: SeaBird CTD 9-11

Supplied Description:

HOT CTD data are collected using a SeaBird CTD 9-11 (9-11 Plus
with dual sensors as of HOT-54) at the maximum sampling rate
of 24 samples per second (24 Hz).

Instrument Type

Generic Name: CTD Sea-Bird 911

Acronym: CTD SBE 911

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0035/

Generic Description:

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

CTD Sea-Bird SBE 911plus

Supplied Name: SeaBird CTD 9-11 Plus

Supplied Description:

HOT CTD data are collected using a SeaBird CTD 9-11 (9-11 Plus
with dual sensors as of HOT-54) at the maximum sampling rate
of 24 samples per second (24 Hz).

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 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

Supplied Name	Supplied description	Supplied Units	Standard Name
cruise_name	cruise identifier	unitless	cruise_id
station	station identifier	unitless	sta
cast	CTD cast number	unitless	cast
depth_max	Depth meassured by shipboard echo sounder in meters. The nominal depth for Station 1 = 1500m and for Station 2 = 4750m.	meters (m)	depth
timecode	The code for when the time was taken. At the beginning (BE); bottom (BO); and completion (EN) of the cast.	unitless	unknown
HOT_summary_file_name	Filename from which the cruise summary information was obtained	unitless	file_name
parameters	A list of the parameters measured from the water samples collected during the cast. The identification numbers are listed here. 1 = Salinity; 2 = Oxygen; 3 = Silicate; 4 = Nitrate; 5 = Nitrite; 6 = Phosphate; 7 = Freon 11; 8 = Freon 12; 9 = Tritium; 10= Helium; 11= Carbon 14; 12= Carbon 13; 13= Krypton 85; 14= Argon; 15= Argon 39; 16= Neon; 17= Radium; 18= Radium 226; 19= o18/o16 ratio; 20= Stronitum 90; 21= Cesium 137	unitless	unknown
num_bottles	The number of bottles used during the cast.	unitless	unknown
section	The WHP section designator.	unitless	unknown
lon	longitude with west being negative	decimal degrees	lon
comments	cast comments	unitless	comment
Date	The date of the cast in MMDDYY.	untiless	unknown
Day	Day of the month value as extracted from the Date field	unitless	day
EXPOCODE	This code allows for the identification of cast. It consists of a 4 character NODC country-ship code; a maximum of 8 character cruise number followed by a "_" and leg number.	unitless	EXPOCODE
lat	latitude with south being negative	decimal degrees	lat
nav_code	navigation system code	unitless	unknown
pres_max	The deepest pressure sampled.	decibars (db)	prmax
depth_hgt	Bottom depth less the maximum pressure sampled.	meters (m)	altitude
Month	Month of the year value as extracted from the Date field	unitless	month
timeutc	time in UTC	unitless	time
Year	Four digit year as extracted from the Date field	unitless	year
Ship	This code allows for the identification of cast. It consists of a 4 character NODC country-ship code; a maximum of 8 character cruise number followed by a "/" and leg number.	unitless	unknown
CTDTMP	Temperature (Degrees Celsius International Temperature Scale of 1988)	Degrees Celsius	temp
NUMBER	Number of observations averaged at this pressure level	count	count
CTDPRS	Pressure (Decibars)	Decibars (db)	press
CTDOXY	Oxygen (micromoles per kilogram)	micromoles per kilogram (umol/kg)	O2_umol_kg
XMISS	Transmission (% transmission)	percent transmission (%)	trans
QUALT1	Quality (defined by investigator); The quality word is the left-to-right concatenation of required quality bytes for the variables measured. They are defined as follows: 1 = Not calibrated with water samples; 2 = Acceptable measurement; 3 = Questionable measurement; 4 = Bad measurement; 5 = Not reported; 6 = Interpolated value; 7 = Not assigned for CTD data; 8 = Not assigned for CTD data; 9 = Not sampled	unitless	q_code
CTDSAL	Salinity (1978 International Practical Salinity Scale)	PSU	sal
CHLPIG	Chloropigments (microgram/liter)	microgram per liter (ug/L)	pig_tot
NITRATE	Nitrate (micromoles per kilogram) after HOT-176	micromoles per kilogram (umol/kg)	NO3
FLUOR	fluorescence	mVOLTS	fluor
ISO_DateTime	time in ISO-8601 format following the convention YYYY-mm-ddTHH:MM:SS[.xx]Z (UTC time)	unitless	ISO_DateTime_UTC

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