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Diagnosing diapycnal mixing from passive tracers
Name
[15200485 - Journal of Physical Oceanography] Diagnosing Diapycnal Mixing from Passive Tracers.pdf
Description
Published version
Size
919.06 KB
Format
Adobe PDF
Checksum (MD5)
1f2b82fcd1069e754f2c18364b9a0017
Author(s)
RUAN, XIAOZHOU
FERRARI, RAFFAELE
Date Issued
2021
Journal
Journal of Physical Oceanography
Publisher
American Meteorological Society
Version
Final published version
Abstract
© 2021 American Meteorological Society. Turbulent mixing across density surfaces transforms abyssal ocean waters into lighter waters and is vital to close the deepest branches of the global overturning circulation. Over the last 20 years, mixing rates inferred from in situ microstructure profilers and tracer release experiments (TREs) have provided valuable insights in the connection between small-scale mixing and large-scale ocean circulation. Problematically, estimates based on TREs consistently exceed those from collocated in situ microstructure measurements. These differences have been attributed to a low bias in the micro-structure estimates that can miss strong, but rare, mixing events. Here we demonstrate that TRE estimates can suffer from a high bias, because of the approximations generally made to interpret the data. We first derive formulas to estimate mixing from the temporal growth of the second moment of a tracer patch by extending Taylor’s celebrated formula to account for both density stratification and variations in mixing rates. The formulas are validated with tracers released in numerical simulations of turbulent flows and then used to discuss biases in the interpretation of TREs based estimates and how to possibly overcome them.
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
10.1175/JPO-D-20-0194.1
