EVAPOTRANSPIRATION FROM AN IRRIGATED TURF UNDER ADVECTION OF DRY AIR AT DAVIS, CALIFORNIA.
CALIFORNIA UNIV DAVIS DEPT OF WATER SCIENCE AND ENGINEERING
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Detailed micrometeorological data were collected during three periods in October 1966 and 1967 at Davis, California when dry, northerly winds passed from an extensive dry area onto a moist irrigated grass field. The two studies which comprise this report use these data to test several advection models. Goltz and Pruitt, using 13-14 October 1966 data, studied the horizontal extent of the transition zone of surface evaporative flux and the magnitude and variation of evapotranspiration within this zone, using three independent methods. The results of these studies showed the reduction of evapotranspiration 117 meters downwind from the leading edge of an irrigated grass field under conditions of strong advection of cool, dry air to be, in general, 20 to 25 percent, with all three independent methods providing compatible results. Indications were that even at this distance into the grass field, evapotranspiration reductions had not completely stabilized. Decker, using Philips model for advection, tested the variation of evapotranspiration over the same irrigated grass field during conditions of mild advection of warm, dry air represented by the 7 and 9 October 1967 data. He found that predicted values of surface evapotranspiration during inversion periods compared quite closely to values of evapotranspiration measured by the 20-foot weighing lysimeter located 100 meters downwind in the grass field. Author