Preprints
https://doi.org/10.5194/bg-2020-43
https://doi.org/10.5194/bg-2020-43

  28 Feb 2020

28 Feb 2020

Review status: this preprint has been withdrawn by the authors.

On evapotranspiration and eddy covariance measurements corrections

Bartosz M. Zawilski Bartosz M. Zawilski
  • CESBIO Universit√© de Toulouse, CNES, CNRS, INRA, IRD, UPS, Toulouse, France

Abstract. Eddy Covariance (EC) technique is one of the most used technique monitoring Green House Gases (GHG) fluxes such as H2O, CO2, CH4. Water vapor movement and corresponding air density fluctuations were corrected by Webb et al. (1980) but not water vapor formation. Classic EC technique supposes mean air vertical speed nullity when it cannot be the case because of water evaporation. Water is falling as a liquid, evaporating directly from soil surface, from shallow soil subsurface or either through vegetation transpiration and becomes a gas which corresponds to a notable volume expansion. Water vapor is mounting through atmosphere, compensating in a cloud and falling as a rain (liquid) again. Evaporation and corresponding volume expansion make mean vertical air speed positive (upgoing) and influence more or less a flux balance following concerned gas or energy. A simple accessing and corresponding correction for the half hourly summation is given and applied to a 11-month real set of data. These corrections allow to explain, in part, most observed eddy covariance discrepancies.

This preprint has been withdrawn.

Bartosz M. Zawilski

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Bartosz M. Zawilski

Bartosz M. Zawilski

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This preprint has been withdrawn.

Short summary
One of the most used techniques in order to assess the greenhouse gases flux is the Eddy Covariance (EC) technique that supposes the mean air vertical speed nullity. While working extensively with another technique used for soil effluxes measurements: dynamically closed chambers, it became obvious that there is a mass flow from the soil, it means that the vertical air speed can only be positive and caused by water evaporation. Based on vapor evaporation rate, EC corrections are very important.
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