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Ben-Gurion University of the Negev (2016)

Latent heat flux over bare soil

Anat Florentin

Titre : Latent heat flux over bare soil

שטף חום כמוס מעל קרקע חשופה בתקופת הקיץ

Auteur : Anat Florentin

Etablissement de soutenance : Ben-Gurion University of the Negev

Grade : Master of Science (MS) 2016

Non-rainfall water inputs (NRWIs), i.e., dew formation, water vapor adsorption, and fog deposition, are of great importance, although their small magnitude, especially in dry desert areas. Their extensive potential impact wide range fields of study, and requires quantification of the phenomenon, while their magnitude challenges the existing measurement methods. Among the current methods used to monitor NRWIs, the microlysimeter (ML), which is based on water balance measurements, was proved accurate and can serve an absolute reference. However, the ML is a point measurement and thus does not account for the natural variability. An alternative for NRWIs measurements, or their energy-equivalent latent heat flux (λE), can be made by applying traditional micrometeorological methods such as the eddy covariance (EC) and scintillometry, with an advantage of covering a larger area. Still, accumulation of NRWIs largely occurs during nighttime, when the atmosphere is typically stable and λE is relatively small, which causes uncertainty. The objective of the research was to measure the diurnal course of λE caused by NRWIs over bare soil in a desert area during the dry season, and thereby test the ability of the micrometeorological methods to quantify NRWIs. Three methods were tested against the ML : the EC, the scintillometer as a measure of sensible heat flux (H), with net radiation and soil heat flux (G) measured independently and λE computed as a residual of the energy balance equation, and the scintillometer along with high frequency measurements of water vapor concentration and applying the flux-variance method.

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