The Penman Monteith equation is the best known approach to estimate evapotraspiration from meteorological data on a daily basis. Limited information is available on its use on an hourly basis mostly because it requires parameterization of aerodynamic and canopy resistance ( ra and rc ) which are difficult to estimate. The objectives of this study were a) develop a new remote sensing approach  to estimate rc and ra  from output of infrared radiometric system ( including meteorological sensors )  b.  Develop a numeric  mathematical model that is capable  of calculating  actual evapotranspiration (ET) from the data collected remotely with infrared radiometer and compare them.

            Infrared radiometers and a conventional meteorological system were stationed on the top of a linear move irrigation system . The output signals were collected remotely on a PC that was equipped with a specific code to solve  Penman-Monteith equation for ra and rc and then used  to calculate the plant water requirement. The software used  the actual ET as boundary conditions for instantaneous calculations of soil water balance components  based on the hydraulic properties of the soil  in the Western Negev (Israel).  Currently,  all components that are required to improve irrigation management are controlled  remotely Including: automatic data collection , models, hardware and  software 

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