abstract angstrom-prescott equation is one of the most commonly used methods for the estimation of global solar radiation (rs) based on sunshine hours. the critical step in the application of this method's is the calibration of its coefficients for each region. although the coefficients of the equation have been calibrated in different parts of the world, the effect of different time scales has...

We present three different methods for the absolute calibration of direct spectral irradiances measured with a Brewer spectroradiometer, which are shown to agree to within +/- 2%. Direct irradiance spectra derived by Brewer and Bentham spectroradiometers agree to within 4 +/- 3%. Good agreement was also found by a comparison of the aerosol optical depth and Angstrom exponent retrieved by the tw...

abstract solar radiation (rs) has many applications in most sciences such as agriculture and irrigation however, its measurement has been done in few weather stations of iran. therefore, estimation methods were used. in this study, weather data of rasht station, from 2004 to 2006 were employed for calibration of some equations, and weather data of years 2007 and 2008 were used for evaluating th...

the solar radiation received by earth surface is one of the most applicable parameter that is so important in hydrology, agriculture, meteorology and climatological modeling. because of very expensive instrument for measuring the radiation, researchers suggested many different experimental equations to estimate this parameter in different climate. seven models which are calibrated for semi-arid...

abstract solar radiation, nowadays has a lot of application in different fields of agriculture, irrigation, and hydrology engineering and due to these various applications, different models has been proposed for it’s estimation. angstrom-prescott equation is one of the most important well known models for solar radiation estimation. this equation has empirically coefficient that various for eac...

AstroSat/UVIT carries two gratings in the FUV channel and a single grating NUV channel. These are useful for low resolution, slitless spectroscopy far near UV bands of variety cosmic sources such as hot stars, interacting binaries, active galactic nuclei, etc. We present calibration these using observations standards NGC40 HZ4. perform wavelength flux derive effective areas different orders. fi...

A new polymorph crystalline silica composition having uniform pore dimensions were synthesized by calcining a crystalline hydrated alkyl-ammonium silicate. The pore dimensions approximately were 6 angstrom for silicalite-1 and 11 angstrom for silicalite-2 units. The silicalite-1 was prepared hydrothermally at a pH of about 10 from a reaction mixture consist of water, amorphous silica and a ...