This project is executed between March 14, 2006 to December 31, 2007 and is in the second year phase. The main tasks are to enhance the reliability of UV-Index forecasting system and to operate and maintain the UV Instrument Calibration Laboratory (UVICL). The maintenance of the UVI forecasting system and the analysis of the UVI monitoring and forecasting results are running very smoothly. The effective monitoring rate is very high and the data has been smoothly collected. The percentage of noontime radiative flux taken up the whole-day radiation is about 72% in winter and 62% in summer. The occurring frequencies of extremely high UVI and UVI≧8 show a seasonal pattern of low value in winter and high value in summer, and vary significantly with region and year. In the meantime, monitoring of UVA and UVI shows a 90% positive correlation. The general characteristics of UVA are very similar to those of UVI. As far as the performance of UVI forecast system is concerned, the error has been minimized gradually, which suggests a stable UVI forecast system just as expected. In order to improve the performance of the UVI forecast system, a numerical simulation approach has been taken to simulate the hourly UVI. The results show some deviation does exist between the simulated and observed results, which should be corrected in the future. Hopefully, we may apply such numerical approach next year so as to enhance the performance of UVI forecast. As to the calibration of second and third standard monitoring instruments, things are running smoothly as expected.

UVI,calibration,forecasting