Articles
SOIL HEAT FLUX IN THE PENMAN-MONTEITH EVAPOTRANSPIRATION EQUATION
Article number
449_8
Pages
69 – 74
Language
Abstract
Some reliable evapotranspiration-estimating methods, like Penman-Monteith’s (Monteith, 1973), require knowledge of the available energy expressed by the difference between net radiation (RN) and soil heat flux (G). G is considered as either zero or portion of RN, changing with the crop development and, thus, with the leaf area index (L). Establishment of a relationship between G/RN and L is attempted here both for day and night time during the development of a crop, under varying soil moisture regimes.
A reliable exponential relation between the two parameters, applicable for crops with varying geometry and architecture of canopy, is proposed for day time.
With L approaching zero, G/RN tends to the value 0.43, whereas for large L, the ratio approaches its limit value 0.1. At night, G/RN and L are related linearly for L>2, but for smaller values of L, G approaches RN.
A reliable exponential relation between the two parameters, applicable for crops with varying geometry and architecture of canopy, is proposed for day time.
With L approaching zero, G/RN tends to the value 0.43, whereas for large L, the ratio approaches its limit value 0.1. At night, G/RN and L are related linearly for L>2, but for smaller values of L, G approaches RN.
Authors
M. Anadranistakis, A. Liakatas, S. Alexandris, S. Aggelides, P. Kerkides, S. Rizos, A. Poulovassilis
Keywords
Leaf area index, extinction coefficient, net radiation
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