Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea

Williams, Charlotte A. J.; Hull, Tom; Kaiser, Jan; Mahaffey, Claire; Greenwood, Naomi; Toberman, Matthew; Palmer, Matthew R.. 2024 Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea. Biogeosciences, 21 (7). 1961-1971. https://doi.org/10.5194/bg-21-1961-2024

Before downloading, please read NORA policies.

Preview

Text bg-21-1961-2024.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (2MB) | Preview

Abstract/Summary

There is an immediate need to better understand and monitor shelf sea dissolved oxygen (O2) concentrations. Here we use high-resolution glider observations of turbulence and O2 concentrations to directly estimate the vertical O2 flux into the bottom mixed layer (BML) immediately before the autumn breakdown of stratification in a seasonally stratified shelf sea. We present a novel method to resolve the oxycline across sharp gradients due to slow optode response time and optode positioning in a flow “shadow zone” on Slocum gliders. The vertical O2 flux to the low-O2 BML was found to be between 2.5 to 6.4 mmol m−2 d−1. Episodic intense mixing events were responsible for the majority (up to 90 %) of this oxygen supply despite making up 40 % of the observations. Without these intense mixing events, BML O2 concentrations would approach ecologically concerning levels by the end of the stratified period. Understanding the driving forces behind episodic mixing and how these may change under future climate scenarios and renewable energy infrastructure is key for monitoring shelf sea health.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5194/bg-21-1961-2024
ISSN:	1726-4189
Date made live:	10 Jun 2024 16:20 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537549

Actions (login required)

View Item

Document Downloads

More statistics for this item...