Article
 

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

Público Deposited

Contenido Descargable

Descargar PDF
https://ir.library.oregonstate.edu/concern/articles/xp68km34h

Descriptions

Attribute NameValues
Creator
Abstract
  • Extracting benthic oxygen fluxes from eddy covariance time series measured in the presence of surface gravity waves requires careful consideration of the temporal alignment of the vertical velocity and the oxygen concentration. Using a model based on linear wave theory and measured eddy covariance data, we show that a substantial error in flux can arise if these two variables are not aligned correctly in time. We refer to this error in flux as the time lag bias. In one example, produced with the wave model, we found that an offset of 0.25 s between the oxygen and the velocity data produced a 2-fold overestimation of the flux. In another example, relying on nighttime data measured over a seagrass meadow, a similar offset reversed the flux from an uptake of -50 mmolm⁻² d⁻¹ to a release of 40 mmolm⁻² d⁻¹. The bias is most acute for data measured at shallow-water sites with short-period waves and low current velocities. At moderate or higher current velocities (>5–10 cm s⁻¹), the bias is usually insignificant. The widely used traditional time shift correction for data measured in unidirectional flows, where the maximum numerical flux is sought, should not be applied in the presence of waves because it tends to maximize the time lag bias or give unrealistic flux estimates. Based on wave model predictions and measured data, we propose a new time lag correction that minimizes the time lag bias. The correction requires that the time series of both vertical velocity and oxygen concentration contain a clear periodic wave signal. Because wave motions are often evident in eddy covariance data measured at shallow-water sites, we encourage more work on identifying new time lag corrections.
  • This discussion paper has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.biogeosciences-discuss.net/12/8395/2015/bgd-12-8395-2015.html The final revised paper is available at: http://hdl.handle.net/1957/http://hdl.handle.net/1957/58000
License
Resource Type
DOI
Fecha Disponible
Fecha de Emisión
Citation
  • Berg, P., Reimers, C. E., Rosman, J. H., Huettel, M., Delgard, M. L., Reidenbach, M. A., and Özkan-Haller, H. T.: Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves, Biogeosciences, 12, 6721-6735, https://doi.org/10.5194/bg-12-6721-2015, 2015.
Journal Title
Journal Volume
  • 12
Journal Issue/Number
  • 11
Academic Affiliation
Declaración de derechos
Funding Statement (additional comments about funding)
  • This study was supported by grants from the National Science Foundation (OCE-1061108, OCE-1061218, OCE-1061364, OCE-1334848, and OCE 1334117) and the University of Virginia.
Publisher
Peer Reviewed
Language
Replaces

Relaciones

Parents:

This work has no parents.

Elementos

Miniatura Título Fecha de subida Visibilidad Acciones
file details ReimersCCEOASTechnicalNoteTime_DiscussionPaper_.pdf 2017-10-16 Público Descargar