ESTIMATION OF HORIZONTAL SOLAR UV-A RADIATION AND ITS MODIFIED MAP

Abstract

Solar ultraviolet(UV) radiation is one of major degradation factors for polymeric building materials. Horizontal UV-A (wave range: 315-400 nm) is observed at Choshi and Miyakojima outdoor exposure fields for two years. Hourly UV-A radiation is expressed as a function of solar altitude and global solar energy(wave range: 305-2800 nm). Citing hourly solar radiation observed around Japan for 1991-2000, UV-A radiation is estimated and compiled as database. Yearly/monthly total of UV-A energy maps are showing local difference and seasonal fluctuation. The previous solar UV energy map(1987) by demolished sensor, EKO MS-140 shall be replaced by new one.