Dataset: Temperature, salinity, fluorescence, and dissolved O2/Ar ratios measured continuously underway onboard basin-wide transects of the North Pacific from Hong Kong to Long Beach, CA

Final no updates expectedDOI: 10.26008/1912/bco-dmo.831046.1Version 1 (2020-11-20)Dataset Type:Cruise Results

Principal Investigator: Paul Quay (University of Washington)

Co-Principal Investigator, Contact: Hilary I. Palevsky (University of Washington)

BCO-DMO Data Manager: Dana Stuart Gerlach (Woods Hole Oceanographic Institution)


Project: North Pacific Surface Carbon, Oxygen and Isotope Measurements from Container Ships (2008-) (NPac Cont Ship)


Abstract

Temperature, salinity, fluorescence, and dissolved O2/Ar ratios were measured continuously from an underway seawater system on board commercial container ships OOCL Tianjin and OOCL Tokyo. Measurements were made from May 2011 to August 2012 during basin-wide transects of the North Pacific Ocean while traversing from Hong Kong to Long Beach, CA

Measurements
Measurements for O2/Ar dissolved gas ratios, temperature, salinity, and fluorescence were continuously measured from an underway seawater system (10 m depth) on basin-wide transects of the North Pacific between Hong Kong and Long Beach, California onboard the M/V OOCL Tianjin and the M/V OOCL Tokyo (each individual transect has a unique Cruise ID). Sea surface temperature and salinity at the time of sample collection were determined using a Sea-Bird Electronics SBE45 thermosalinograph (TSG) installed in the ship’s seawater intake. Fluorescence was measured using a Seapoint Chlorophyll Fluorometer.  This dataset presents uncalibrated data; the discrete calibration data are in https://www.bco-dmo.org/dataset/626855.

Underway measurements of O2/Ar dissolved gas ratios were made using continuous flow equilibrator inlet mass spectrometry (EIMS), following the method of Cassar et al. (2009). Water from the underway seawater system was pumped into an equilibrator cartridge (Membrana MicroModule G569, 0.75” x 1”), the headspace of which was delivered to a quadrupole mass spectrometer (Pfeiffer Prisma QMS) that measured individual ion currents at one-second intervals. To prevent biofouling that could cause respiration in the ship’s seawater lines (Juranek et al., 2010), intake lines between the anticorrosive sea chest and the sampling port were purged with bleach and freshwater between every cruise.

NOTE: Since the samples were collected underway on a vessel moving ~24 knots and samples for all parameters were collected by a single shiprider, ship transit from the time that the location coordinates were recorded to the time of actual sampling could reflect a transit distance offset from the recorded location of up to 40 kilometers.

Methods and Calculations
Methods are described in detail in Clayton et al. (in preparation for JGR: Oceans). 

To aid in interpretation of the O2/Ar data provided here, we include calculations of the air-sea flux of biological oxygen driven by the biological saturation anomaly (O2Arbiosat), termed “bioflux” by Jonsson et al. [2013]:
                             Air_sea_flux = k*[O2]eq*(O2Arbiosat/100)

Where k represents the wind speed-dependent air-sea gas transfer velocity and [O2]eq is the oxygen concentration that would be expected in the mixed layer were it in equilibrium with the atmosphere. We calculate k from daily wind speed data from the NOAA National Climatic Data Center’s multiple-satellite Blended Sea Winds product (https://www.ncdc.noaa.gov/data-access/marineocean-data/blended-global/blended-sea-winds) following the Nightingale et al. (2000) equation and the 60-day (Reuer et al., 2007) time-dependent weighting scheme. We report k here as “Wkn” representing the weighted k value using the Nightingale algorithm. In conditions with limited influence of physical advection, entrainment, and transient changes due to non-steady state conditions over the dissolved gas residence time in the mixed layer, bioflux is equivalent to net community production. However, there are potential biases in quantifying net community production based on observed O2/Ar in dynamic western boundary current regions where steady state assumptions are likely invalid and strong vertical turbulent dissipation rates have been observed.

The following are additional details for relevant fields in this dataset:

  • TrueO2Ar:  ratio of dissolved O2/dissolved Ar in surface seawater as measured by continuous underway equilibrator inlet mass spec, and calibrated with discrete samples from existing dataset (https://www.bco-dmo.org/dataset/626855).
  • O2Arsat: O2/Ar ratio expected if both gases were in equilibrium with the atmosphere, which is a function of Salinity and Temperature (Garcia and Gordon, 1992; Hamme and Emerson, 2007)
  • O2Arbiosat:  percent supersaturation of O2 in surface seawater, calculated from the TrueO2Ar and O2Arsat [O2Arbiosat = (TrueO2Ar/O2Arsat – 1)*100]
  • MLD: climatological mixed layer depth from monthly World Ocean Atlas 2013 (with 1 degree gridded data)
  • Wkn: air-sea gas transfer velocity in m/day, calculated using a relationship between wind speed and gas transfer from Nightingale et al. (2000) and the NOAA/NCDC Blended Sea Winds satellite wind speed product (Zhang et al. 2006), and using the Reuer et al. (2007) time-dependent weighting scheme and the MLD values given here.

Related Datasets

References

Dataset: O2/Ar and triple oxygen isotopes discrete samples
Relationship Description: Discrete samples from dataset 626855 (O2/Ar and triple oxygen isotopes) were used to calibrate the TrueO2Ar measurements for dataset 831046 (Continuous underway data)
Quay, P. (2016) Dissolved gas O2/Ar and triple oxygen isotope discrete samples collected from 16 basin-wide transects of the North Pacific, Hong Kong - Long Beach, CA from the M/V OOCL Tianjin and M/V OOCL Tokyo, 2008-2012 (NPac Cont Ship project). Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 2016-02-03) Version Date 2016-02-03 http://lod.bco-dmo.org/id/dataset/626855

Related Publications

Methods

Cassar, N., Barnett, B. A., Bender, M. L., Kaiser, J., Hamme, R. C., & Tilbrook, B. (2009). Continuous High-Frequency Dissolved O2/Ar Measurements by Equilibrator Inlet Mass Spectrometry. Analytical Chemistry, 81(5), 1855–1864. doi:10.1021/ac802300u
Methods

Clayton, S., Palevsky, H. I., Thompson, L., & Quay, P. D. (2021). Synoptic Mesoscale to Basin Scale Variability in Biological Productivity and Chlorophyll in the Kuroshio Extension Region. Journal of Geophysical Research: Oceans, 126(11). Portico. https://doi.org/10.1029/2021jc017782
Methods

Garcia, H. E., & Gordon, L. I. (1992). Oxygen solubility in seawater: Better fitting equations. Limnology and Oceanography, 37(6), 1307–1312. doi:10.4319/lo.1992.37.6.1307
Methods

Hamme, R. C., & Emerson, S. R. (2004). The solubility of neon, nitrogen and argon in distilled water and seawater. Deep Sea Research Part I: Oceanographic Research Papers, 51(11), 1517–1528. doi:10.1016/j.dsr.2004.06.009
Methods

Jonsson, B. F., Doney, S. C., Dunne, J., & Bender, M. (2013). Evaluation of the Southern Ocean O2/Ar-based NCP estimates in a model framework. Journal of Geophysical Research: Biogeosciences, 118(2), 385–399. https://doi.org/10.1002/jgrg.20032