Dataset: Water Mass Fractions - 39 yrs

Name: The fraction of water last ventilated in a given region in a time less than or equal to 39 years ago based on samples collected from R/V Knorr cruises KN199-04 and KN204-01 during 2010-2011
Published: 2020-05-07
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.810838.1

Spatial Extent: N:39.701 E:-9.662 S:17.351 W:-69.827

Temporal Extent: 2010-10-16 - 2011-12-10

Project:

Collaborative Research: Completing a 10-Year Record of Deep Western Boundary Current Observations at Line W; A Contribution to the Atlantic Meridional Overturning Circulation Study (DWBC Obs Line W)

RAPID: Continuation of U.S. GEOTRACES North Atlantic Section: CFC and SF6 Measurements (GT NAT RAPID CFC SF6)

U.S. GEOTRACES North Atlantic Section: CFC and SF6 Measurements (GT NAT CFC and SF6)

U.S. GEOTRACES North Atlantic Transect (GA03) (U.S. GEOTRACES NAT)

Program:

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

Principal Investigator:

William M. Smethie Jr. (Lamont-Doherty Earth Observatory, LDEO)

Co-Principal Investigator:

Mark Holzer (University of New South Wales, UNSW)

Yu-Heng Ting (University of New South Wales, UNSW)

Contact:

Mark Holzer (University of New South Wales, UNSW)

BCO-DMO Data Manager:

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

Version:

Version Date:

2020-05-07

Restricted:

Validated:

Yes

Current State:

Final no updates expected

The fraction of water last ventilated in a given region in a time less than or equal to 39 years ago based on samples collected from R/V Knorr cruises KN199-04 and KN204-01 during 2010-2011

Abstract:

Water mass fractions and ages calculated from hydrographic and tracer data using a maximum-entropy inversion technique. This dataset contains the fraction of water last ventilated in a given region in a time less than or equal to 39 years ago as well as the corresponding ensemble standard deviations.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2020-05-07	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.810838.1	2020-05-27

Description

Water mass fractions and ages calculated from hydrographic and tracer data using a maximum-entropy inversion technique.

This dataset contains the fraction of water last ventilated in a given region in a time less than or equal to 39 years ago as well as the corresponding ensemble standard deviations.

Data File Formats:
For a .csv or .tsv format of these data, use the "Get Data" button at the top of the BCO-DMO metadata page.
For a Matlab file containing all of the water mass fraction data from this project, see the "Data Files" section of the BCO-DMO metadata page.

Methods & Sampling

A maximum-entropy inversion technique was applied to CFC and SF6 measurements made on the U.S. GEOTRACES North Atlantic Transect, and radiocarbon concentrations interpolated to sample locations along the transact from gridded data reported in the GLODAP data compilation, to determine mean ages and source water compositions of each water sample. Details are described in Holzer et al. (2018).

See the attached README file (GA03_transit-time_partitioned_water-mass_fractions_v2_README.pdf) for more information on methods and a map of region locations.

Data Files

File

Matlab structure containing GA03 water-mass fraction data
filename: wmf_ages_bottleIDs_GA03.mat

(MATLAB Data (.mat), 279.73 KB)
MD5:b1c644f9f0726e2c8e6b5d453be80293

Water-mass fractions (wmf) are organized into 668x8 matrices: There are 668 bottle locations along section GA03 and the columns are the fraction of water last ventilated in one of 8 surface regions. This file contains the single matlab structure GA03, which has the following double-precision fields:

field name             size precision   units

---------------------------------------------------------

wmf_tau_all_yr         [668×8 double]   fraction of unity

wmf_tau_all_yr_uncert  [668×8 double]   fraction of unity

wmf_tau_le160yr        [668×8 double]   fraction of unity

wmf_tau_le160yr_uncert [668×8 double]   fraction of unity

wmf_tau_le39yr         [668×8 double]   fraction of unity

wmf_tau_le39yr_uncert  [668×8 double]   fraction of unity

age_regional           [668×7 double]   years

age_regional_uncert    [668×7 double]   years

ideal_mean_age         [668×1 double]   years

ideal_mean_age_uncert  [668×1 double]   years

depth [668×1 double]   m

lat [668×1 double]   degrees north

lon [668×1 double]   degrees east

dist_east [668×1 double]   km

wmf_tau_le39yrs.csv

(Comma Separated Values (.csv), 163.09 KB)
MD5:9ef24692cdd70af650bbe251d26c3ea6

Primary data file for dataset ID 810838

Supplemental Files

File
README file for GA03 transit-time partitioned water-mass fractions datasets filename: GA03_transit-time_partitioned_water-mass_fractions_v2_README.pdf (Portable Document Format (.pdf), 328.76 KB) MD5:b190a3a2811f95658ad399cf907c8283 README file for GA03 transit-time partitioned water-mass fractions datasets contributed by William M. Smethie Jr.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-0928612
NSF Division of Ocean Sciences	OCE-1132545
NSF Division of Ocean Sciences	OCE-1332834

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
KN199-04	GA03 GT10 USGT-NAT-2010 KN199-4 GNAT U.S. GEOTRACES NAZT Leg 1 knorr199-4/5 Section Cruise (GA03) 316N20101015	2010-10-15	R/V Knorr	William J. Jenkins (Chief Scientist) Edward A. Boyle (Co-Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info
KN204-01	GA03 GT11 KN204-01A KN204-01B USGT-NAT-2011 USGNAZT GNAT 316N20111106 KN204-1	2011-11-06	R/V Knorr	Edward A. Boyle (Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info

Instruments

None available yet

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
Ideal_Mean_Age	estimate of the ideal mean age (regardless of last ventilation location) at each of the 668 bottle locations	years	age
Ideal_Mean_Age_Uncert	ensemble standard deviation of the Ideal_Mean_Age	years	age
Sample_Bottle	Bottle number	unitless	bottle
Cast_No	Cast number	unitless	cast
Cruise_ID	Cruise identifier	unitless	cruise_id
Date	Sampling date; format: yyyymmdd	unitless	date
Depth	Bottle sample depth	meters (m)	depth
Latitude	Bottle sample latitude	degrees North	lat
Longitude	Bottle sample longitude	degrees East	lon
LBIR_Fraction	fraction of water last ventilated in the LBIR region; LBIR = Labrador and Irminger Seas	unitless (fraction)	no_bcodmo_term
LBIR_Fraction_Uncert	ensemble standard deviation of the LBIR_Fraction	unitless (fraction)	no_bcodmo_term
AONG_Fraction	fraction of water last ventilated in the AONG region; AONG = Arctic Ocean, Greenland, and Norwegian Seas	unitless (fraction)	no_bcodmo_term
AONG_Fraction_Uncert	ensemble standard deviation of the AONG_Fraction	unitless (fraction)	no_bcodmo_term
SPNA_Fraction	fraction of water last ventilated in the SPNA region; SPNA = SubPolar North Atlantic	unitless (fraction)	no_bcodmo_term
SPNA_Fraction_Uncert	ensemble standard deviation of the SPNA_Fraction	unitless (fraction)	no_bcodmo_term
Distance_East	The distance in kilometers along the combined cruise tracks of the KN199-04 and KN204-01 from the easternmost station (KN204-01 station 1).	kilometers (km)	no_bcodmo_term
STNA_Fraction	fraction of water last ventilated in the STNA region; STNA = SubTropical North Atlantic	unitless (fraction)	no_bcodmo_term
STNA_Fraction_Uncert	ensemble standard deviation of the STNA_Fraction	unitless (fraction)	no_bcodmo_term
MED_Fraction	fraction of water last ventilated in the MED region; MED = Mediterranean Sea	unitless (fraction)	no_bcodmo_term
MED_Fraction_Uncert	ensemble standard deviation of the MED_Fraction	unitless (fraction)	no_bcodmo_term
NAAD_Fraction	fraction of water last ventilated in the NAAD region; NAAD = North of the Antarctic Divergence	unitless (fraction)	no_bcodmo_term
NAAD_Fraction_Uncert	ensemble standard deviation of the NAAD_Fraction	unitless (fraction)	no_bcodmo_term
SAAD_Fraction	fraction of water last ventilated in the SAAD region; SAAD = South of the Antarctic Divergence	unitless (fraction)	no_bcodmo_term
SAAD_Fraction_Uncert	ensemble standard deviation of the SAAD_Fraction	unitless (fraction)	no_bcodmo_term
OTHER_Fraction	fraction of water last ventilated in the OTHER region; OTHER = the rest of the global sea surface, exluding the other defined areas	unitless (fraction)	no_bcodmo_term
OTHER_Fraction_Uncert	ensemble standard deviation of the OTHER_Fraction	unitless (fraction)	no_bcodmo_term
Station_No	Station number	unitless	station