Dataset: Water Mass Fractions - Ages

Name: Mean ventilation age reported for 7 regions of the Atlantic 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.810885.1

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

Mean ventilation age reported for 7 regions of the Atlantic 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 (PID)	Date PID Issued
2020-05-07	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.810885.1	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_ages.csv

(Comma Separated Values (.csv), 152.90 KB)
MD5:44504d68a1bf704ecd3cd5d52d2f8493

Primary data file for dataset ID 810885

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
LBIR_Age	regional mean ventilation age for the LBIR region; LBIR = Labrador and Irminger Seas	years	age
LBIR_Age_Uncert	ensemble standard deviation of LBIR_Age	years	age
AONG_Age	regional mean ventilation age for the AONG region; AONG = Arctic Ocean, Greenland, and Norwegian Seas	years	age
AONG_Age_Uncert	ensemble standard deviation of AONG_Age	years	age
SPNA_Age	regional mean ventilation age for the SPNA region; SPNA = SubPolar North Atlantic	years	age
SPNA_Age_Uncert	ensemble standard deviation of SPNA_Age	years	age
STNA_Age	regional mean ventilation age for the STNA region; STNA = SubTropical North Atlantic	years	age
STNA_Age_Uncert	ensemble standard deviation of STNA_Age	years	age
MED_Age	regional mean ventilation age for the MED region; MED = Mediterranean Sea	years	age
MED_Age_Uncert	ensemble standard deviation of MED_Age	years	age
NAAD_Age	regional mean ventilation age for the NAAD region; NAAD = North of the Antarctic Divergence	years	age
NAAD_Age_Uncert	ensemble standard deviation of NAAD_Age	years	age
SAAD_Age	regional mean ventilation age for the SAAD region; SAAD = South of the Antarctic Divergence	years	age
SAAD_Age_Uncert	ensemble standard deviation of SAAD_Age	years	age
OTHER_Age	regional mean ventilation age for OTHER is not reported because OTHER is the rest of the global sea surface not included in the 7 Atlantic regions	years	age
OTHER_Age_Uncert	ensemble standard deviation of OTHER_Age (not reported)	years	age
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
Depth	Bottle sample depth	meters (m)	depth
Latitude	Bottle sample latitude	degrees North	lat
Longitude	Bottle sample longitude	degrees East	lon
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
Cruise_ID	Cruise identifier	unitless	cruise_id
Station_No	Station number	unitless	station
Cast_No	Cast number	unitless	cast
Sample_Bottle	Bottle number	unitless	bottle
Date	Sampling date; format: yyyymmdd	unitless	date