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Hourly oxygen and total gas tension measurements at the Southern Ocean Time Series site reveal winter ventilation and spring net community production

Citation

Weeding, B and Trull, T, Hourly oxygen and total gas tension measurements at the Southern Ocean Time Series site reveal winter ventilation and spring net community production, Journal of Geophysical Research: Oceans, 119, (1) pp. 348-358. ISSN 2169-9275 (2014) [Refereed Article]


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Copyright Statement

Copyright 2014 American Geophysical Union

DOI: doi:10.1002/2013JC009302

Abstract

Using a moored instrument package at 35 m depth at the Southern Ocean Time Series (SOTS) site near 46°560S 142°150E from September 2010 to April 2011 (219 days), we obtained the first Southern Ocean Time Series of dissolved oxygen (from an optode sensor) and nitrogen (from a total gas tension sensor). Nitrogen was consistently supersaturated (100.8%-102.9%), while oxygen was highly subsaturated in early spring (as low as 93.5%) and reached supersaturation (maximum 104.9%) during only 37 days in early summer. The low oxygen levels in spring illustrate the importance of deep mixing in the Subantarctic Zone in ventilating the upper limb of the global overturning circulation. Using nitrogen as a proxy for physical processes, we isolated biological contributions to the oxygen time series to obtain net community production (NCP). Almost all NCP occurred in spring in the presence of deep mixed layers, with only small additional contributions in summer after water column stratification. The temperature and salinity time series also revealed distinct parcels of water. Rapid changes at their interfaces generated unrealistic NCP events in the standard calculation model, which were removed, while still retaining NCP contributions from each parcel. NCP totaled 2.261.2 mol O2 m22 over the deployment, within the range of previous estimates from low temporal resolution techniques. Examination of errors revealed particular sensitivity to entrainment, suggesting more rigorous understanding of this process is required, e.g., via profiling instruments. ©2013. American Geophysical Union. All Rights Reserved.

Item Details

Item Type:Refereed Article
Keywords:net community production, dissolved oxygen, total gas tension, Southern Ocean, moorings
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Physical and Chemical Conditions of Water
Objective Field:Physical and Chemical Conditions of Water in Marine Environments
Author:Weeding, B (Mr Ben Weeding)
Author:Trull, T (Professor Thomas Trull)
ID Code:92303
Year Published:2014
Web of Science® Times Cited:12
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2014-06-13
Last Modified:2017-11-01
Downloads:0

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