Lagrangian Studies of Net Community Production: The Effect of Diel and Multiday Nonsteady State Factors and Vertical Fluxes on O2/Ar in a Dynamic Upwelling Region

Seaver Wang, Sven A. Kranz, Thomas B. Kelly, Hajoon Song, Michael R. Stukel, Nicolas Cassar

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The ratio of dissolved oxygen to argon in seawater is frequently employed to estimate rates of net community production (NCP) in the oceanic mixed layer. The in situ O2/Ar-based method accounts for many physical factors that influence oxygen concentrations, permitting isolation of the biological oxygen signal produced by the balance of photosynthesis and respiration. However, this technique traditionally relies upon several assumptions when calculating the mixed-layer O2/Ar budget, most notably the absence of vertical fluxes of O2/Ar and the principle that the air-sea gas exchange of biological oxygen closely approximates net productivity rates. Employing a Lagrangian study design and leveraging data outputs from a regional physical oceanographic model, we conducted in situ measurements of O2/Ar in the California Current Ecosystem in spring 2016 and summer 2017 to evaluate these assumptions within a “worst-case” field environment. Quantifying vertical fluxes, incorporating nonsteady state changes in O2/Ar, and comparing NCP estimates evaluated over several day versus longer timescales, we find differences in NCP metrics calculated over different time intervals to be considerable, also observing significant potential effects from vertical fluxes, particularly advection. Additionally, we observe strong diel variability in O2/Ar and NCP rates at multiple stations. Our results reemphasize the importance of accounting for vertical fluxes when interpreting O2/Ar-derived NCP data and the potentially large effect of nonsteady state conditions on NCP evaluated over shorter timescales. In addition, diel cycles in surface O2/Ar can also bias interpretation of NCP data based on local productivity and the time of day when measurements were made.

Original languageEnglish
Article numbere2019JG005569
JournalJournal of Geophysical Research G: Biogeosciences
Issue number6
Publication statusPublished - 2020 Jun 1

Bibliographical note

Funding Information:
This research was made possible by a RAPID NSF OCE‐1614359 and federal funding provided to the California Current Ecosystem (CCE) LTER project, NSF OCE‐1637632. H. S. acknowledges the support by National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT) (NRF‐2019R1C1C1003663) and Yonsei University Research Fund of 2018‐22‐0053. We are sincerely grateful to the captain, crew, and marine technicians of the and the for their assistance prior to and during our 2016 and 2017 expeditions. We are additionally thankful for helpful suggestions and input from Susan Lozier, Laifang Li, Sijia Zou, and Kimberly Drouin, as well as reviewer feedback from Roberta Hamme and one anonymous reviewer. We also thank Susan Becker, Melissa Miller, and Megan Roadman for their assistance processing and analyzing collected Winker samples. We are additionally grateful to Ralf Goericke for his help processing vessel cruise data and to Chief Scientist Mark Ohman and the rest of the CCE LTER team. Lastly, we thank the staff of Scripps Institution of Oceanography for their cruise logistical and organizational support. The authors declare no conflict of interest. Data reported and presented in this study can be accessed under the P1706 and P1604 categories at the CCE‐LTER Datazoo online database ( ). R/V Sikuliaq R/V Roger Revelle

Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.

All Science Journal Classification (ASJC) codes

  • Soil Science
  • Forestry
  • Water Science and Technology
  • Palaeontology
  • Atmospheric Science
  • Aquatic Science
  • Ecology


Dive into the research topics of 'Lagrangian Studies of Net Community Production: The Effect of Diel and Multiday Nonsteady State Factors and Vertical Fluxes on O2/Ar in a Dynamic Upwelling Region'. Together they form a unique fingerprint.

Cite this