Dataset: Discrete O2 Ar

Name: Discrete O2 Argon (Ar) from NOAA Ship Ronald H. Brown cruise RB-08-02 in the Southwest Atlantic sector of the Southern Ocean near South Georgia Island in 2008 (SO_GasEx project)
Published: 2013-10-14
Keywords: oceans

Cite This Dataset

Spatial Extent: N:-35.5495 E:-36.1171 S:-53.7527 W:-55.4999

Project:

Southern Ocean Gas Exchange Experiment (SO_GasEx)

Program:

Ocean Carbon and Biogeochemistry (OCB)

United States Surface Ocean Lower Atmosphere Study (U.S. SOLAS)

Principal Investigator:

Roberta C. Hamme (University of Victoria, UVic)

Co-Principal Investigator:

Dr Michael L. Bender (Princeton University)

Dr Nicolas Cassar (Duke University)

Contact:

Burke Hales (Oregon State University, OSU-CEOAS)

BCO-DMO Data Manager:

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

Version:

14 October 2013

Version Date:

2013-10-14

Validated:

Current State:

Preliminary and in progress

Discrete O2 Argon (Ar) from NOAA Ship Ronald H. Brown cruise RB-08-02 in the Southwest Atlantic sector of the Southern Ocean near South Georgia Island in 2008 (SO_GasEx project)

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Description

Dataset Description:
Final Discrete Oxygen/Argon, Nitrogen/Argon, and triple Oxygen Isotope Data along with associated productivity calculations

Operation Description:
Discrete measurements of oxygen/nitrogen/argon ratios (ONAr) and triple oxygen isotopes for productivity calculations.

Methods & Sampling

Sampling times and locations:
Sampled ONAR on every Niskin Rosette cast at 5m except stations 8 and 9 when the mass spec was out of commission. Duplicates were collected on approximately one cast per day in the latter portion of the cruise. Two short profiles in the upper 100m were collected on Stations 6 and 16. See CTD cast logs and bottle files for specific times, locations, and flask numbers for each cast. Discrete samples were also collected from the underway seawater line near the EIMS instrument.

Overall sampling strategy:
Plan was to collect discrete samples from the surface on every CTD cast and from the underway system at other times to provide discrete data every 6-12 hours.

Data Processing Description

Analytical method:
Flasks provided by Bender Lab. Each flask has HgCl2 dried onto the inside. Flasks were evacuated in the Bender Lab prior to the cruise. Back at the lab, sample flasks were weighed. The headspace is allowed to equilibrate with the water sample at room temperature, followed by removal of the water phase. Approximately half the samples are analyzed using a Finnigan DeltaPlus XP mass spectrometer for measurement of O2/N2/Ar as well as d18O of O2 and d15N of N2. Others are chromatographed to separate O2 and Ar from N2, followed by analysis of O2/Ar and the triple isotope composition of O2 using a Finnigan MAT 252 mass spectrometer. Air standards are processed in the same way and used to calibrate the mass spec standard. Uncertainties based on duplicates from this cruise were +/- 0.23% in O2/Ar and +/- 0.0052 ‰ in the mass-independent fractionation anomaly of 17O.

Calculations:
O2/Ar and N2/Ar ratios are corrected for the gases remaining in the water phase, so that the provided values represent whole sample ratios. Isotopes of O2 are not corrected for this fractionation, so that provided values represent those in the headspace only. Saturations are calculated based on Garcia and Gordon (1992,1993) for O2 and Hamme and Emerson (2004) for Ar and N2. Net community oxygen production is calculated from the O2/Ar data, T, S, and a weighted gas exchange rate. This value approximates the NOP of the mixed layer over 10 days prior to the measurement of O2/Ar. Gross productivities are calculated from the O2 isotope data and a windspeed parameterization based on the calculation method of Kaiser (2011). For gas exchange, we use the Reuer et al. (2007) wind speed weighting over 60 days prior to the measurement using combined QuikSCAT/NCEP wind speeds and the Ho et al. (2006) gas exchange parameterization. For more details see Hamme, R. C., et al. (2012), Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean, J. Geophys. Res., 117, C00F12, doi:10.1029/2011JC007046.

BCO-DMO Processing Notes
Original file: "Hamme2012_discrete.csv" contributed by Roberta Hamme
Metadata file: "Metadata_report_DiscreteO2Ar_Final.xls" contributed by Roberta Hamme
- year, month, date combined into a single date field formatted as YYYYMMDD
- hour, minute, second combined into a single time field formatted as HHMMSS
- Parameter names edited to conform to BCO-DMO parameter naming conventions

Data Files

File
Discrete_O2_Ar.csv (Comma Separated Values (.csv), 20.55 KB) MD5:1c5a0d7cb09916e2538107f2801b621e Primary data file for dataset ID 4058

More Information about this dataset

Funding Sources

Funding Source	Award Number
National Aeronautics & Space Administration	NNX08AF12G
National Oceanic and Atmospheric Administration	unknown SO_GasEx NOAA
NSF Antarctic Sciences	PLR-0636744
National Sciences and Engineering Research Council of Canada	328290-2006

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
RB-08-02	RB0802 RHB_SO-GasEx	2008-02-29	NOAA Ship Ronald H. Brown	Christopher L. Sabine (Chief Scientist) David T. Ho (Co-Chief Scientist)	data info

Instruments

CTD Sea-Bird SBE 911plus

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

Gas Chromatograph

Supplied Description:

Others are chromatographed to separate O2 and Ar from N2

Instrument Type

Generic Name: Gas Chromatograph

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB02/

Generic Description:

Instrument separating gases, volatile substances, or substances dissolved in a volatile solvent by transporting an inert gas through a column packed with a sorbent to a detector for assay. (from SeaDataNet, BODC)

Mass Spectrometer

Supplied Name: Finnigan DeltaPlus XP mass spectrometer

Supplied Description:

Approximately half the samples are analyzed using a Finnigan DeltaPlus XP mass spectrometer for measurement of O2/N2/Ar as well as d18O of O2 and d15N of N2

Instrument Type

Generic Name: Mass Spectrometer

Acronym: Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.

Mass Spectrometer

Supplied Name: Finnigan MAT 252 mass spectrometer

Supplied Description:

Others are chromatographed to separate O2 and Ar from N2, followed by analysis of O2/Ar and the triple isotope composition of O2 using a Finnigan MAT 252 mass spectrometer.

Instrument Type

Generic Name: Mass Spectrometer

Acronym: Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

Niskin bottle

Supplied Description:

Instrument Type

Generic Name: Niskin bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/

Generic Description:

A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.

Pump - Surface Underway Ship Intake

Supplied Name: Pump - surface underway ship intake

Supplied Description:

Discrete samples were also collected from the underway seawater line near the EIMS instrument.

Instrument Type

Generic Name: Pump - Surface Underway Ship Intake

Acronym: Pump-Ship Intake

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/31/

Generic Description:

The 'Pump-underway ship intake' system indicates that samples are from the ship's clean water intake pump. This is essentially a surface water sample from a source of uncontaminated near-surface (commonly 3 to 7 m) seawater that can be pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the underway supply that may also be referred to as the non-toxic supply. Ideally the data contributor has specified the depth in the ship's hull at which the pump is mounted.

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
event_num	Unique event number for CTD/Rosette cast or underway sampling event	YDAHHMM	event
date	date (UTC)	YYYYMMDD	date
time	time (UTC)	HHMMSS	time
latitude	latitude; negative denotes South	decimal degrees	lat
longitude	longitude; negative denotes West	decimal degrees	lon
station	SO-GasEx CTD Station ID (NAN for underway samples)	dimensionless	station
niskin	Rosette Niskin number (NAN for underway samples)	dimensionless	bottle
press	pressure from CTD or presumed from underway inlet location	dbar	press
depth	depth from CTD pressure or presumed from underway inlet location	meters	depth
CTDtemp	Temperature	degrees C	temp
pot_temp	Potential Temperature	degrees C	potemp
CTDsal	salinity; from CTD on PSS-78 scale; (underway salinity from data by David Drapeau measured on a nearby SBE45 but corrected for observed CTD/underway offsets)	PSS-78	sal
sigma_theta	Potential density - 1000	kg/m^3	sigma_theta
in_mixed_layer_flag	1=sample is in mixed layer; 0= sample not in mixed layer	dimensionless	flag
O2_conc	O2 concentration	umol/kg	O2
O2_Ar_ratio	O2/Ar ratio	ratio	no_bcodmo_term
O2_Arsat	O2/Ar supersaturation =( (O2/Ar)meas / (O2/Ar)equil - 1)*100	percentage	no_bcodmo_term
O2_Arsat_std_dev	standard deviation of duplicates for O2/Ar supersaturation (NaN if no duplicate)	percentage	no_bcodmo_term
N2_Ar_ratio	N2/Ar ratio	ratio	no_bcodmo_term
N2_Arsat	N2/Ar supersaturation =( (N2/Ar)meas / (N2/Ar)equil - 1)*100	percentage	no_bcodmo_term
N2_Arsat_std_dev	standard deviation of duplicates for N2/Ar supersaturation (NaN if no duplicate)	percentage	no_bcodmo_term
d17O_headspace	delta17O of O2 in sample headspace	permil	no_bcodmo_term
d17O_headspace_std_dev	standard deviation of duplicates for delta17O of O2 in sample headspace	permil	no_bcodmo_term
d18O_headspace	delta18O of O2 in sample headspace	permil	no_bcodmo_term
d18O_headspace_std_dev	standard deviation of duplicates for delta18O of O2 in sample headspace	permil	no_bcodmo_term
SeventeenD_with_ref_slope_0point5154	17D = (ln(d17Odis/1000 + 1) -0.5154ln(d18Odis/1000 + 1)) 1e6	per meg	no_bcodmo_term
SeventeenD_with_ref_slope_0point5154_std_dev	standard deviation of duplicates for 17D with 0.5154 reference slope	per meg	no_bcodmo_term
SeventeenD_with_ref_slope_0point5179	17D = (ln(d17Odis/1000 + 1) -0.5179ln(d18Odis/1000 + 1)) 1e6	per meg	no_bcodmo_term
SeventeenD_with_ref_slope_0point5179_std_dev	standard deviation of duplicates for 17D with 0.5179 reference slope	per meg	no_bcodmo_term
Net_O2_community_production_based_on_prior_O2_Ar	NOP = kw * O2/Arsat * [O2]equil * density	mmol O2 /m2/d	no_bcodmo_term
Gross_O2_production_based_on_triple_isotopes	GOP calculated from oxygen isotopes; see Hamme et al. 2012 appendix A	mmol O2 /m2/d	no_bcodmo_term
weighted_gas_exchange_coefficient_used_for_productivity_calcs	kw	m/d	no_bcodmo_term
mixed_layer_depth_used_for_gas_exchange_weighting	mixed layer depth for determining kw	meters	depth_mixed_layer

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Dataset: Discrete O2 Ar