Algorithm for Evaluating the Hourly Radiation Utilizability Function

1983 ◽  
Vol 105 (3) ◽  
pp. 281-287 ◽  
Author(s):  
D. R. Clark ◽  
S. A. Klein ◽  
W. A. Beckman
Keyword(s):  
Solar Radiation ◽  
Numerical Integration ◽  
Simple Algorithm ◽  
Threshold Intensity ◽  
Analytical Expression ◽  
Monthly Average ◽  
Radiation Incident ◽  
Solar Radiation Incident ◽  
Radiation Measurements

A computationally simple algorithm is presented for evaluating the hourly utilizability function, φ, defined as the fraction of the long-term, monthly-average, hourly solar radiation incident on a surface which exceeds a specified threshold intensity. The algorithm was developed by correlating values of φ obtained by numerical integration of hourly radiation for three locations. The algorithm is shown to compare well both with a more complex analytical expression for φ developed recently and with results obtained numerically using many years of hourly horizontal radiation measurements in nine U.S. locations. In addition, the algorithm is shown to be applicable for surfaces of any orientation.

scholarly journals Analysis and correlation of ultraviolet solar radiation from routine meteorological measurements over Egypt

MAUSAM ◽  
2021 ◽  
Vol 51 (3) ◽  
pp. 275-280
Author(s):  
A. I. SALEM
Keyword(s):  
Regression Analysis ◽  
Solar Radiation ◽  
Arabian Peninsula ◽  
Global Radiation ◽  
Global Solar Radiation ◽  
Correlation Equations ◽  
Monthly Average ◽  
Solar Radiation Incident ◽  
Radiation Measurements ◽  
Ultraviolet Solar Radiation

For three years (1990-92) measurements of the monthly average daily global, G, and ultraviolet, UV, solar radiation incident on a horizontal surface at Cairo (30°15'N, 31°17'E) and Aswan (23°58'N, 32°47'E) are presented. processed and analysed. It was found that the computed monthly average daily values for the obtained solar radiation components, G and UV, were (18.1 MJ/m2, 0.55 MJ/m2, for Cairo and (22.1 MJ/m2, 0.71 MJ/m2, for Aswan. The effect of atmospheric dust on the measured solar radiation components is also investigated and discussed. The ratio of the ultraviolet to global radiation (UV/G) are calculated and compared with other sites in the Arabian Peninsula. A regression analysis has been done to find a correlation between G and UV at the selected sites during the three year period and the recommended correlation equations have also been stated.   Since the meteorological measurements of UV solar radiation are not available over Egypt. except at Cairo (Lower Egypt) and Aswan (Upper Egypt) stations, our correlation equations can be used to calculate this component from the available global solar radiation measurements at any site in the two zones of Upper and Lower Egypt.

Frequency Distributions for Hourly and Daily Clearness Indices

2001 ◽  
Vol 124 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Manuel Iban˜ez ◽  
William A. Beckman ◽  
Sanford A. Klein
Keyword(s):  
Solar Radiation ◽  
Recent Literature ◽  
Weather Data ◽  
Clearness Index ◽  
Frequency Distributions ◽  
Monthly Average ◽  
Daily Frequency ◽  
Better Than ◽  
Exponential Probability

The clearness index for hourly and daily radiation is an important parameter in describing solar radiation. Liu and Jordan demonstrated that the monthly average daily clearness index could be used to predict the long-term distribution of daily solar radiation in a month. This paper reviews recent literature on the prediction of hourly and daily frequency distributions and cumulative frequency distributions of clearness indices. Ten years of measured weather data for six cities in the U.S. are used to investigate the nature of the hourly and daily frequency distributions. A second set of ten years of data for six cities is used to verify the predictions. A bi-exponential probability density function is proposed that fits the observed bimodal nature of the data better than existing models. A case is made for the function being universal.

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