A Method for Determining the Solar Global and Defining the Diffuse and Beam Irradiation on a Clear Day
Amiran Ianetz and Avraham Kudish 1 Introduction The terrestrial solar irradiation is a function of solar altitude, site altitude, albedo, atmospheric transparency and cloudiness. The atmospheric transparency is a function …
New Methodfor Estimating the Fractal Dimension of Discrete Temporal Signals
In order to contribute in improving the accuracy of fractal dimension estimation of the discrete temporal signals we developed a simple method based on a covering by rectangles called Rectangular …
Recent Advances in the Relations between Bright Sunshine Hours and Solar Irradiation
Bulent G. Akinoglu 1 Introduction It seems quite a realistic view to state that the data of bright sunshine hours are the only long term, reliable and readily available measured …
Instrumentation: Solar Radiometer
A pyrheliometer measures B, the direct beam radiation. Pyrheliometers have a narrow aperture (generally between 5° and 6° total solid angle), admitting only beam radiation with some inadvertent circumsolar contribution …
Daily Distributions of Global Radiation
The most important, probably, study on the daily global irradiation distributions, cited in most works, is that by Liu and Jordan (1960). Based on this study, several works have been …
Secondary Data Sources
Appropriate models are now widely used to fill gaps in measured data, expand their measurement period (to, e. g., 30 years), and estimate solar radiation either at specific sites where …
Solar Global Irradiation on a Clear Day
It is of interest to study the solar global irradiation on a clear day, which is a function of all the abovementioned parameters with the exception of degree of cloudiness, …
Classification of the Solar Irradiances to Typical Days
4.2 A Survey of Existing Methods Modeling random fluctuations of the solar irradiance has already been the object of several studies published in the literature. These are based mostly on …
Measurements and Data Availability
In the construction and validation of all types of models and/or correlations accurate long-term and spatially wide range surface data is needed. In addition to this, and may be more …
Radiometric Reference and Calibration Methods
In this section, we discuss both calibration and characterization of solar radiometers. According to he United States National Institute of Standards and Technology (NIST) Engineering Statistics Handbook (available at http://www. …
Hourly Distributions of Global Radiation
The number of studies about the hourly irradiance is less than for longer time scales. Some authors, as Engels et al. (1981) or Olseth and Skartveit (1987, 1993) emphasise that …
Data Quality Assessment
The simplest approach to quality assessment of solar radiation data is comparison with physical limits. Are the data within “reasonable” bounds? Another basis for data quality assessment is Eq. (1.1), …
Models for Determining the Global Irradiation on Clear Day
The clear day solar global irradiation intensity at a particular site is also an inherent function of the day for which it is determined, since the extraterrestrial irradiation varies from …
Fractal Classification of Solar Irradiance Methodology
Our method classification uses the fractal dimension as a basic criterion to achieve the classification of the solar irradiance and to yield different types of days, i. e., clear sky …
Angstrom-Prescott Relation and its Physical Significance
Prescott at 1940 used the data recorded in Mount Stramlo Observatory in Canberra- Australia. Instead of perfect clear sky value of Angstrom, he used the published data of Angot’s (as …
The Solar Radiation Measurement Reference: WRR
There is no laboratory artifact for direct calibration of broadband solar radiometers. Instead, the Sun itself is used as a source. A group of specialized ACR instruments (first mentioned in …
Distributions of Diffuse and Direct Components of Global Radiation
Research about the direct and diffuse components of the solar radiation is less prolific, mainly because of the scarce availability of such data. Moreover, most of the direct component analyses …
Quality Assessment Based Upon Physical Limits
As the name implies, the physical limits approach to solar data quality assessment compares measured data with estimated or defined limits. For instance, is the radiation component within the range …
Berlynd Model for Determining Global Irradiation on Clear Days
In 1956 Berlynd proposed a model, which is a function of astronomical parameters, albedo and meteorological parameters, that is reported in Kondratyev (1969) and is given as Gc = Gsccos …
Fractal Treatment of Solar Irradiances
Figure 2.5 presents two examples of the log-log lines permitting the estimation of the fractal dimension of irradiance curves. This figure shows that the log-log points are grouped around the …
Calibration of Solar Radiometers
Since the WRR/WSG is the only reference for solar radiometer calibrations, pyrhe - liometers are calibrated by direct comparison with an ACR traceable to the WRR. The calibration of working …
Modelling the Instantaneous Distributions Conditioned by the Optical Air Mass
There are two types of approach to obtain the statistical behaviour of solar radiation: the study of the distributions conditioned by the optical air mass and the study of the …
Quality Assessment Based Upon Closure
An alternative to the physical limits approach is to rely on Eq. (1.1), the theoretical relation between the three components. This approach has important advantages: it is objective and can …
Correlation Between Clear Day Global Index Kc and Kj
It is of interest to utilize the clear day solar global irradiation to determine a ‘daily clear day index’, Kc, which we define as Kc = H/Hc, (4.9) viz., the …
Annually and Monthly Classification Analysis
The thresholds Dj and Djj have first been determined for the sites of Tahifet and Imehrou. For this purpose, the heuristic method and the statistical one has been used, Table …
Uncertainty and Characterization of Solar Radiometers
Every measurement only approximates the quantity being measured, and is incomplete without a quantitative uncertainty. ISO defines uncertainty as: A parameter, associated with the result of a measurement that characterizes …
Statistical Investigation of the Clearness Index
7.1.1 Bimodal Character of the Probability Density Functions The measurements of instantaneous solar radiation values allow to considerer the effect of optical air mass. As a consequence, the distributions conditioned …
