Temporal variability of near-bottom dissolved oxygen during upwelling off central Oregon
Article first published online: 2 OCT 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Oceans
Volume 118, Issue 10, pages 4839–4854, October 2013
How to Cite
2013), Temporal variability of near-bottom dissolved oxygen during upwelling off central Oregon, J. Geophys. Res. Oceans, 118, 4839–4854, doi:10.1002/jgrc.20361., , and (
- Issue published online: 26 NOV 2013
- Article first published online: 2 OCT 2013
- Accepted manuscript online: 24 AUG 2013 01:24AM EST
- Manuscript Accepted: 18 AUG 2013
- Manuscript Revised: 9 JUL 2013
- Manuscript Received: 21 NOV 2012
- interannual variability;
- shelf circulation
 In the productive central-Oregon coastal upwelling environment, wind-driven upwelling, tides, and topographic effects vary across the shelf, setting the stage for varied biogeochemical responses to physical drivers. Current, temperature, salinity, and dissolved oxygen (DO) measurements from three moorings deployed during the upwelling seasons of 2009–2011 off the central-Oregon coast are analyzed over three time bands (interannual, subtidal, tidal) to explore the relationship between mid (70 m) and inner-shelf (15 m) upwelling dynamics and the associated effect on DO. Topographic effects are observed in each time band due to the Heceta and Stonewall Bank complex. Seasonal cumulative hypoxia (DO < 1.4 mL L−1) calculations identify two regions, a well-ventilated inner shelf and a midshelf vulnerable to hypoxia (98 ± 15 days annually). On tidal timescales, along-shelf diurnal (K1) velocities are intensified over the Bank, 0.08 m s−1 compared with 0.03 m s−1 to the north. Interannual variability in the timing of spring and fall transitions, defined using glider-measured continental slope source water temperature, is observed on the midshelf. Interannual source water DO concentrations vary on the order of 0.1 mL L−1. Each spring and summer, DO decline rates are modulated by physical and biological processes. The net observed decrease is about 30% of the expected draw down due to water-column respiration. Physical processes initiate low-oxygen conditions on the shelf through coastal upwelling and subsequently prevent the system via advection and mixing from reaching the potential anoxic levels anticipated from respiration rates alone.