Development and Characterization of a New Solar Ultraviolet-B Irradiance Detector

Esteve

et al. 2011

UV erythemal irradiance (UVER) has been studied on a horizontal plane and on vertical surfaces with different orientations in Valencia, Spain. The evolution of the solar noon value and the maximum daily value over a year has been analysed from the instantaneous UVER taken every five minutes on the horizontal plane and on vertical surfaces with north, south, east and west orientations. The annual evolution of these values shows a sinusoidal form for all planes except for the vertical south plane with maxima in spring and autumn. The UV Index (UVI) on these planes was also determined. The percentage of coincidence of the UVI at solar noon and of the maximum daily UVER values, considering differences of 1 or 0 units, is 87% on the horizontal plane, 100% on the vertical north plane, 92% on the vertical south plane, 77% on the vertical east plane and 75% on the vertical west plane. We have compared the UVI of the vertical plane with the horizontal one by means of linear regressions. All planes show very good correlations except for the vertical south plane, which shows no correlation with the horizontal plane for the middle days of the year due to its particular geometry with respect to the Sun's apparent path. Finally, the annual cumulative UVER doses related to each phototype for the horizontal and vertical planes were calculated. It was noticed that the dose over a year on the horizontal plane doubles the dose on the vertical south plane, which is the one that receives the maximum dose.

Section: Methodssupporting

confidence: 89%

UV Index experimental values on vertical surfaces

Esteve

et al. 2011

“…The UVB-1 is designed to be stable over long periods of time and to operate continuously and autonomously in the field. The cosine response is less than 4% for solar zenith angles below 55° (Dichter et al, 1993) according to the manufacturer. This instrument was subjected to a standard calibration in the National Institute for Aerospace Technology (INTA) in Spain.…”

Section: Methodsmentioning

confidence: 99%

Ozone mini‐holes over Valencia (Spain) and their influence on the UV erythemal radiation

Núñez

et al. 2011

Low ozone level episodes (also known as mini-holes) have been analysed over Valencia, Spain, during the period from 1 January 2000 to 31 December 2007. In this study, 24 episodes, lasting 1 or 2 days each, were detected. Most of them can be explained dynamically by the existence of an anticyclone over the Azores, which sends air masses coming from the Caribbean over the Iberian Peninsula. A positive anomaly in the vertical temperature profile in the high troposphere and one negative anomaly in the medium and low stratosphere are also observed in most of the analysed episodes. The total ozone column decrease is accompanied by a rise in the UV erythemal radiation levels. This increase is quantified at 1.29 times the decrease in the total ozone column. This is known as the radiation amplification factor (RAF) of UV erythemal radiation.

“…Measurements were taken and stored with the same procedure used in the above cases. The cosine response is less than 3.8% for SZAs below 70° (Dichter et al, 1993). Calibration is carried out by comparison with a precision spectrometer (Optronic OL-754).…”

Section: Instrumentation and Measurementsmentioning

confidence: 99%

The erythemal clearness index for Valencia, Spain

Tena

et al. 2008

ABSTRACT:The values of three clearness indices have been measured for the city of Valencia: k t , the clearness index for the whole solar spectrum, k tUV the clearness index for the ultraviolet range, and the erythemal clearness index for the erythemal radiation k tUVER , corresponding to the solar radiation weighted by the erythemal action spectrum on human skin, normalized with respect to the solar constant corresponding to that spectrum. The measurements of k tUV reached values that were approximately 54% of that corresponding to k t , while those of k tUVER were much smaller. Some statistics of the erythemal clearness index have been calculated both for monthly as well as hourly means. The shape of the distribution in both cases was nearly normal, so standard deviation and variance were used to analyse the dispersion of the data. The ratio of the erythemal clearness index and the corresponding solar irradiance was also studied. When only the central hours of the day were considered the relation between the two was markedly linear, giving a correlation coefficient that reached 99%.