On the diffuse fraction of daily and monthly global radiation for the island of Cyprus

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Solar Energy

DOI:https://doi.org/10.1016/0038-092X(96)81162-5· OSTI ID:501972

Jacovides, C P ^[1]; Hadjioannou, L; Pashiardis, S; Stefanou, L ^[2]

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1. Univ. of Athens (Greece)
2. Meteorological Service of Cyprus, Nicosia (Cyprus)

Six years of hourly global and diffuse irradiation measurements on a horizontal surface performed at Athalassa, Cyprus, are used to establish a relationship between the daily diffuse fraction and the daily clearness index. Two types of correlations - yearly and seasonal - have been developed. These correlations, of first and third order in the clearness index are compared to the various correlations established by Collares-Pereira and Rabl (1979), Newland (1989), Erbs et al. (1982), Rao et al. (1984), Page (1961), Liu and Jordan (1960) and Lalas et al. (1987). The comparison has been performed in terms of the widely used statistical indicators (MBE) and (RMSE) errors; and additional statistical indicator, the t-statistic, combining the earlier indicators, is introduced. The results indicate that the proposed yearly correlation matches the earlier correlations quite closely and all correlations examined yield results that are statistically significant. For large K{sub t} > 0.60 values, most of the earlier correlations exhibit a slight tendency to systematically overestimate the diffuse fraction. This marginal disagreement between the earlier correlations and the proposed model is probably significantly affected by the clear sky conditions that prevail over Cyprus for most of the time as well as atmospheric humidity content. It is clear that the standard correlations examined in this analysis appear to be location-independent models for diffuse irradiation predictions, at least for the Cyprus case. 13 refs., 5 figs., 4 tabs.

• OSTI ID: 501972
• Journal Information: Solar Energy, Journal Name: Solar Energy Journal Issue: 6 Vol. 56; ISSN SRENA4; ISSN 0038-092X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
29 ENERGY PLANNING, POLICY, AND ECONOMY
99 GENERAL AND MISCELLANEOUS
CYPRUS
DATA COMPILATION
DIFFUSE SOLAR RADIATION
MATHEMATICAL MODELS
MONTHLY VARIATIONS
SOLAR RADIATION
STATISTICAL DATA
STATISTICS