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| Titel |
Sensible heat fluxes by scintillometry and eddy covariance in an irrigated vineyard |
| VerfasserIn |
Nadia Vendrame, Luca Tezza, Andrea Pitacco |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138134
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| Publikation (Nr.) |
 EGU/EGU2017-1060.pdf |
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| Zusammenfassung |
| Evapotranspiration (ET) measurements over inhomogeneous and extensive surfaces - typical
conditions at the catchment scale - are still challenging due to spatial variability of
vegetation, soil conditions and land topography. Traditional micrometeorological
techniques, e.g. eddy covariance (EC), cannot be applied under these conditions,
requiring homogenous surface and being characterized by limited footprint. In this
context, a suitable technique to measure turbulent fluxes is scintillometry, which
can give measurements of sensible heat flux at larger scale, providing averages
over heterogeneous surfaces. ET can then be estimated as residual of the energy
budget.
In this study, we present results from a one-week campaign held during summer 2016 in
Southern Italy. We deployed a Large Aperture Scintillometer (LAS) in an extensive vineyard
of 140 ha on a path length of 760 m. The site was characterized by gently slope terrain with
uniform crop. However, spatial and temporal variability of soil water content was expected
due to irrigation shift rotation among different plots. In order to have reference measurements
of local sensible heat flux, we deployed three sonic anemometers along the scintillometer
path, representative of different irrigation schedules. In addition, the EC station close to the
middle of the path was equipped with an open-path infrared gas analyzer, net radiometer and
soil heat flux plates to solve the energy budget. The aim of the study was to test the
ability of scintillometry to provide a spatially averaged flux, representative of the
possibly diverse conditions in an extended footprint upwind to the measurement
path.
The heat flux measured by LAS (HLAS) showed to be extremely sensitive to the value of
beam effective height (zeff) used in data processing (zeff = 6.4 m, above a canopy height of
1.8 m). The relationship between sensible heat flux measured by EC (HEC) and
HLASshowed to be very good (HLAS = 1.06 HEC+ 1.73, r2 = 0.97) for the EC station in the
middle of the path. On the contrary, HLASwas higher compared to HECfor the EC stations
close to the path ends, resulting in an overestimation of the average EC flux of
around 20%. Scintillometer measurements showed to be highly influenced by the
central area of the path, whereas off-center fluxes were not adequately represented. |
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