✦ LIBER ✦

Estimation of direct solar beam irradiance from measurements of the duration of bright sunshine

✍ Scribed by Stanhill, G.

Publisher: John Wiley and Sons
Year: 1998
Tongue: English
Weight: 80 KB
Volume: 18
Category: Article
ISSN: 0899-8418
DOI: 10.1002/(sici)1097-0088(19980315)18:3<347::aid-joc239>3.0.co;2-o

No coin nor oath required. For personal study only.

✦ Synopsis

Measurements of the duration of bright sunshine, n, using the Campbell-Stokes sunshine recorder are shown to be highly correlated with those obtained using a normal incidence pyrheliometer to measure direct irradiance, I, at two sites in the very dissimilar radiation climates of Israel and Ireland. The statistical relationships are presented for a variety of time-scales, ranging from annual to hourly totals. For individual mean monthly values the common linear relationship was I= 2.209 n-0.955 MJ m -2 day -1 , with a standard error of estimate of 91.368 MJ m -2 day -1 and a coefficient of determination of r 2 =0.969.

Analysis of long-term series of sunshine hour measurements indicate that reductions in direct irradiance have occurred at both measurement sites.

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