accurate estimation of reference evapotranspiration plays a key role in water resources management and irrigation scheduling. the fao penman-monteith (f-p-m) is a reference method for calculation of evapotranspiration that needs temperature, humidity, wind speed and solar radiation. in many stations, it is not an easy task to measure the whole weather variables. thus, in this situation, one mus...

Operational ground-based measurements of snow water equivalent (SWE) do not adequately explain spatial variability in mountainous terrain. To address this problem, we combine satellite-based retrievals of fractional snow cover for the period 20 0 0 to 2011 with spatially distributed energy balance calculations to reconstruct SWE values throughout each melt season in the Sierra Nevada of Califor...

introduction:                                                                             the erroneous move towards the modern lifestyles has led to uncontrolled population growth, urbanization, disorderly expansion of cities to natural habitats and ecosystems, destruction of traditional rural communities and farm lands, indiscriminate utilization and destruction of natural resources, growth o...

The variety of radiative models for solar UV radiation is discussed. For the evaluation of measured UV radiation at the ground the basic problem is the availability of actual values of the atmospheric parameters that influence the UV radiation. The largest uncertainties are due to clouds and aerosol, which are highly variable. In the case of tilted receivers, like the human skin for most orient...

Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Measurement of solar radiance demands expensive devices to be used. Alternatively, estimator models are used instead. In this paper, a new method based on the empirical equations is introduced to estimate the monthly average daily global solar radiation on a horizontal surface. The proposed method uses Intelligent Water ...

The energy received by solar collectors for power generation is limited to various conditions. The average data on solar irradiation are normally used to determine the potential of solar energy at any location. However, the variation of solar energy due to seasonal differences could affect the actual performance of the collectors, consequently leading to poorly justified system installations, w...

in order to study of the radiation interception and red to far red light ratio variations in sunflower hybrids under drought stress, nine sunflower hybrids in three separate experiments were compared as randomized complete block designs with three replications at the research station of seed and plant improvement institute in karaj in 2006. first experiment (control) was irrigated based on 60 m...

T e influence of pixel heterogeneity, background, atmospheric and bidirectional effects on the relationship between fraction of photosynthetically active radiation absorbed by the photosynthesizing tissue in a canopy (FAPAR) and normalized difference vegetation index (NDVI) is investigated using a three-dimensional model of radiation transfer. Top of the canopy (TOC) NDVI and FAPAR increase wit...