Surface albedo estimates based on optical and microwave satellite data were compared to corresponding ground based values in a Subarctic boreal forest test site. The ground based albedo values were derived from radiation measurements carried out at the forest floor using an albedo model and measured global and diffuse radiation data. The use of both optical and microwave satellite data turned o...

In order to design a solar energy system with optimized performance a through knowledge of solar radiation data for a considerably long period (20-25 years) is a pre-requisite. For developing countries like Pakistan, the need of empirical models to assess the feasibility of solar energy utilization seems inevitable due to the absence and scarcity of trust-worthy solar radiation data. We present...

An effective three-dimensional (3D) data representation is required to assess the spatial distribution of the photovoltaic potential over urban building roofs and facades using 3D city models. Voxels have long been used as a spatial data representation, but practical applications of the voxel representation have been limited compared with rasters in traditional two-dimensional (2D) geographic i...

The separation models are tools used in solar engineering to estimate direct normal (DNI) and diffuse horizontal (DHI) irradiances from measurements of global irradiance (GHI). This paper proposes two empirical that stand out owing their simple mathematical formulation: a rational polynomial equation. Validation the new was carried against data 36 locations, covering four major climatic zones. ...

We present a new model for the calculation of the diffuse fraction of the global solar irradiance for solar system simulations. The importance of an accurate estimation of the horizontal diffuse irradiance is highlighted by findings that an inaccurately calculated diffuse irradiance can lead to significant overor underestimations in the annual energy yield of a photovoltaic (PV) system by as mu...

S urface solar radiation is a major component of the surface heat budget. Diurnally and seasonally averaged over the entire Earth, 188 ± 7 W m–2 reach the surface to be either absorbed (~165 ± 6 W m–2) or reflected back to the atmosphere (Trenberth et al. 2009; Stephens et al. 2012). Changes in the amount of solar radiation received at the surface are intrinsically tied to the total amount of p...

background: ionizing radiation is present in all environment of the earth’s surface, beneath the earth and in the atmosphere. human beings are exposed to external radiation from their surroundings naturally and also to internal radiation from food, water and air they consume. then, it is important to measure and develop knowledge about radiation. objective: this study is designed to evaluate th...