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Evapotranspiration (ET) refers to the combined processes which move water from the Earth's surface (open water and ice surfaces, bare soil and vegetation) into the atmosphere. [ 2 ] : 2908 It covers both water evaporation (movement of water to the air directly from soil, canopies , and water bodies) and transpiration (evaporation that occurs ...
Crop coefficients are properties of plants used in predicting evapotranspiration (ET). The most basic crop coefficient, K c, is simply the ratio of ET observed for the crop studied over that observed for the well calibrated reference crop under the same conditions.
Monthly estimated potential evapotranspiration and measured pan evaporation for two locations in Hawaii, Hilo and Pahala. Potential evapotranspiration is usually measured indirectly, from other climatic factors, but also depends on the surface type, such as free water (for lakes and oceans), the soil type for bare soil, and also the density and diversity of vegetation.
It is a steel container 1.83 m (6 ft) on a side and 0.61 m (2 ft) deep, sunk into the ground with an above-ground rim of 7.6–10 centimetres (3.0–3.9 in) and is painted black internally. Its evaporation rate is lower than the Class A pan and conversion factors must be used. [8]
The Penman-Monteith equation approximates net evapotranspiration (ET) from meteorological data as a replacement for direct measurement of evapotranspiration. The equation is widely used, and was derived by the United Nations Food and Agriculture Organization for modeling reference evapotranspiration ET 0 .
Chloroplasts in leaf cells containing chlorophyll. Evapotranspiration is the combined processes moving water from the earth’s surface into the atmosphere. Transpiration is the movement of water through a plant and out of its leaves and other aerial parts into the atmosphere.
Two major factors influence the rate of water flow from the soil to the roots: the hydraulic conductivity of the soil and the magnitude of the pressure gradient through the soil. Both of these factors influence the rate of bulk flow of water moving from the roots to the stomatal pores in the leaves via the xylem. [7]
The Standardized Precipitation Evapotranspiration Index (SPEI) is a multiscalar drought index based on climatic data. It was developed by Vicente-Serrano et al. (2010) at the Institute Pirenaico de Ecologia in Zaragoza, Spain . [ 1 ]