Monthly clearness index values of Turkey by harmonic analysis approach

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


The clearness index is among the most significant concepts in solar engineering. It gives more information about the atmospheric characteristics of solar stations in addition to the degree of solar energy potential of stations and their surrounding areas. Most often, the clearness index is related to sunshine duration measurements at a single station without spatial feature searches. In this study, harmonic analysis is used to model the monthly clearness index values recorded at nine stations of Turkey with distinct meteorological conditions. Consequently, the coefficients of harmonics, amplitude variances and phase angles of the harmonics are calculated, and then, maps of the total variances are evaluated for spatial interpolations. It is seen that up to the seventh harmonic, more than 90% of the total variance can be presented. It is shown that the western and eastern parts of Turkey have nearly similar characteristics. The contribution of each harmonic to total variance is calculated, and then, regional variance maps are evaluated.

Original languageEnglish
Pages (from-to)933-940
Number of pages8
JournalEnergy Conversion and Management
Issue number8
Publication statusPublished - May 2001


Dive into the research topics of 'Monthly clearness index values of Turkey by harmonic analysis approach'. Together they form a unique fingerprint.

Cite this