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Submarine Canyon Oxygen Anomaly Caused by Mixing and Boundary‐Interior Exchange
Author(s) -
McPheeShaw Erika E.,
Kunze Eric,
Girton James B.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl092995
Subject(s) - canyon , geology , submarine canyon , hotspot (geology) , buoyancy , oxygen , turbulence , oceanography , isotopes of oxygen , mineralogy , atmospheric sciences , geophysics , geomorphology , meteorology , chemistry , mechanics , geochemistry , physics , organic chemistry
Closely spaced CTD stations showed elevated oxygen within Monterey Submarine Canyon. Anomalously high (2–5 μmol kg −1 ) dissolved oxygen was found between 600–1,100 m in the O 2 minimum, co‐located with a turbulence hotspot caused by convergence of upcanyon, semidiurnal internal tidal energy flux. Furthermore, the oxygen anomaly extended >10 km downcanyon at the same depth and isopycnals of a previously identified intrusion predicted from buoyancy conservation. We show that dissolved oxygen and fine suspended particles act as independent tracers to (a) validate previous microstructure observations of intense turbulence extending >400 m above the bed (mab) at the canyon hotspot, and (b) track boundary‐interior exchange driven by mixing in the form of isopyncal‐spreading of anomalies away from a near‐boundary source. This study demonstrates the use of oxygen, commonly measured with shipboard profiling, as a tool for tracking mixing and lateral dispersal.