Surface Level Solar Ultraviolet-B Radiation At Penang
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Date
2006-06
Authors
Karuppusamy, Arunasala Pandy Ail
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Broadband photometric measurements of solar UV-B, UV -A, global and diffuse
radiation were made at Universiti Sains Malaysia (USM), Penang from 1994 to 2001.
Results from this study show that the large temporal variations for the measured solar
radiation is due to the dominant effect of solar zenith angle and clouds. Under all sky
conditions, the mean daily total radiation values for the UV-B, UV-A and global
radiation were 1.514 x 104 J m-2, 4.69 x lOS J m-2 and 1.80 x 107 J m-2 respectively. For
cloudless sky days, the daily maximum UV-B and global irradiance were 1.372 W m-2
and 1.423 kW m-2. The measured effective UV-B irradiance was converted to the
erythemal UV flux to relate it to the potential harmful effects due to UV exposure; UVB
flux level is in the High or Extreme ranges between 1030 and 1530 hours local time.
A study of the diurnal variation of the solar UV -B, UV-A and global radiation show
that for similar zenith angles, the solar irradiance after solar noon is larger than that
before solar noon. This assymmetrical effect is attributed to the scattering of solar
radiation by clouds. Seasonal variation studies show a constant periodicity for the solar
UV-B, UV-A and global flux with maximums in March and September. Using
available meteorological parameters and total column ozone data, their effects on the
surface level solar UV -B radiation was investigated. A mathematical model to estimate the surface level solar UV-8 radiation was also developed and compared with two
established model. The spectral model performance is good with a mean error of9.9%.
To compliment the spectral model, a simple empirical model was also formulated using
multivariate analysis. The mean error of the empirical model was 2.5%.
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Keywords
Physics