A model for estimating solar ultraviolet radiation for vitamin D photosynthesis

Abstract

Solar ultraviolet radiation has impacts on human health both beneficial and drawback. Excessive exposure to high energy of solar ultraviolet radiation is hazardous for human. For instant, it can create cataracts, skin cancer and immune system suppression. On the contrary, solar ultraviolet radiation helps in the vitamin D photosynthesis in the human skin. It is required in the operation of synthesize previtamin D in the epidermis to 25 hydroxyvitamin D via the kidneys and liver. The solar ultraviolet radiation for vitamin D photosynthesis (DUV) can be obtained from a Bentham spectrophotometer together with the CIE action spectral response of vitamin D. However, such ground-based spectrophotometer instrument in Thailand is very scarce. Therefore, this research focuses on developing an empirical model for calculating hourly DUV under all sky conditions using several atmospheric parameters at a solar monitoring site in the central region of Thailand. The input parameters of the model include total ozone column from OMI/AURA satellite, aerosol optical depth from an AERONET sunphotometer, cloud index from geostationary satellite, and air mass from a well-known equation. The data used in this research are totally three years (2016-2018). The analysis result indicates that the solar DUV obtained from the model calculation and that from the ground-based measurement are consistent with the root mean square error (RMSE) of 17.1% and mean bias error (MBE) of –9.2%.