A bi-variable probability density function for the daily clearness index

✍ Scribed by M. Ibáñez; J.I. Rosell; W.A. Beckman

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 416 KB
• Volume: 75
• Category: Article
• ISSN: 0038-092X
• DOI: 10.1016/s0038-092x(03)00123-3

✦ Synopsis

The assumption that probability density functions of daily clearness indices are unimodal was tested. Bimodal behaviour was observed in almost 60% of 600 monthly data sets and was shown to be the most usual shape at 50 locations between latitudes 18.438N and 64.818N and at between 2 and 2297 m above sea level. A bi-exponential probability density function was proposed that fits the observed behaviour of daily clearness indices. The proposed function uses the mean monthly ¯clearness index K and the mean monthly solar height at noon h as inputs. The bi-exponential method for predicting daily