Illustration of micro-scale advection using grid-pattern mini-lysimeters

Diaz-Espejo, A., Verhoef, A. ORCID: https://orcid.org/0000-0002-9498-6696 and Knight, R. (2005) Illustration of micro-scale advection using grid-pattern mini-lysimeters. Agricultural and Forest Meteorology, 129 (1-2). pp. 39-52. ISSN 0168-1923 doi: 10.1016/j.agrformet.2004.12.001

Abstract/Summary

Twenty-five small soil-filled perspex boxes arranged in a square, with dwarf sunflowers growing in them, were used to study micro-scale advection. Hydrological heterogeneity was introduced by applying two different amounts of irrigation water (low-irrigation, L, versus high-irrigation, H). The nine central boxes (4 H, 4 L and I bare box) were precision weighing lysimeters, yielding diurnal measurements of evaporation. After the onset of soil water stress, a large difference in latent heat flux (up to 4-fold) was observed between the lysimeters of the H and L treatments, mainly caused by large differences between H and L stomatal conductance values. This resulted in micro-advection, causing H soil-sunflower systems to evaporate well above equilibrium latent heat flux. The occurrence of micro-advective enhancement was reflected in large values of the Priestley-Taylor constant (often larger than 2.0) and generally negative values of sensible heat flux for the H treatment. (c) 2005 Elsevier B.V. All rights reserved.