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Crop evapotranspiration (ETc) measurement is usually performed by sophisticated sensors that require high technical knowledge and that are not economically affordable for most end users. The objective of this work was to evaluate the performance of a novel LI-710 sensor for measuring ETc on a pistachio orchard. This simplified and easy-to-use sensor applies the Eddy Covariance (EC) method to measure water vapor flux between the surface and the atmosphere, however, it is cheaper and less complex than traditional EC heat flux system. The LI-710 sensor was installed together to an EC tower and the measurements provided by both methodologies were compared. Initial results evidenced a good agreement in terms of the evaluated meteorological variables, except for relative humidity, where higher discrepancies among sensors were observed. Regarding the sensible (H) and latent (LE) heat fluxes, the values measured by both methodologies were similar, with R2 values of 0.96 and 0.80; and RMSE values of 19 and 29 W m−2, respectively. These results suggest that LI-710 sensor can be a valid alternative to traditional EC systems for deriving ETc. However, LI-710 continues to have the fetch limitations presented in traditional methodologies, so future efforts should be paid to reduce this requirement increasing its usability in medium-small sized agricultural plots.
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Intercomparison of eddy-covariance software for urban tall-tower sites
Abstract. Long-term tall-tower eddy-covariance (EC) measurements have been recently established in three European pilot cities as part of the ICOS-Cities project. We conducted a comparison of EC software to ensure a reliable generation of interoperable flux estimates, which is the prerequisite for avoiding methodological biases and improving the comparability of the results. We analyzed datasets covering 5 months collected from EC tall-tower installations located in urbanized areas of Munich, Zurich, and Paris. Fluxes of sensible heat, latent heat, and CO2 were calculated using three software packages (i.e., TK3, EddyPro, and eddy4R) to assess the uncertainty of flux estimations attributed to differences in implemented postprocessing schemes. A very good agreement on the mean values and standard deviations was found across all three sites, which can probably be attributed to a uniform instrumentation, data acquisition, and preprocessing. The overall comparison of final flux time series products showed a good but not yet perfect agreement among the three software packages. TK3 and EddyPro both calculated fluxes with low-frequency spectral correction, resulting in better agreement than between TK3 and the eddy4R workflow with disabled low-frequency spectral treatment. These observed flux discrepancies indicate the crucial role of treating low-frequency spectral loss in flux estimation for tall-tower EC systems.
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- PAR ID:
- 10523739
- Publisher / Repository:
- EGU
- Date Published:
- Journal Name:
- Atmospheric Measurement Techniques
- Volume:
- 17
- Issue:
- 9
- ISSN:
- 1867-8548
- Page Range / eLocation ID:
- 2649 to 2669
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.5194/amt-17-2649-2024
