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Aquatic Eddy Correlation: Quantifying the Artificial Flux Caused by Stirring-Sensitive O₂ Sensors

Figure 1

The predicted artificial flux as a function of stirring sensitivity and Reynolds stress.

A: The O2 concentration measured by a microelectrode increases non-linearly with the current velocity, here shown for a sensor with a stirring sensitivity of 0.7%. As a first approximation, the fluctuating velocities (u’) around their mean () can be transferred to the fluctuating concentrations (c’) around their mean () using the slope of the function at as a transfer factor (red lines in A). B: The first derivative of the transfer function, i.e. the transfer factor, decreases with velocity. C: The Reynolds stress in a logarithmic boundary layer increases as the square of the velocity, here assuming a roughness (z0) of 1 mm and a height above the seabed (z) of 15 cm. D: Applying equation 5, the Reynolds stress and the transfer factor can be combined to estimate the EC-flux from stirring sensitivity as a function of velocity. E: The artificial EC flux is plotted as a function of velocity according to equation 7 and as a function of Ssen (0.5–2%), c∞ (100–300µM) and z0 (0.1–10mm). The combination of parameter values is presented next to the functions.

doi: https://doi.org/10.1371/journal.pone.0116564.g001