The main task of this project, “UV Forecast System and Monitoring Instrument Calibration Lab.-Fiscal year 99” is to enhance the UV forecast and monitoring ability in Taiwan. The objective of this project are :(1)to develop UV Index forecast numerical dynamical model system. (2) To maintain the numerical fidelity of UV monitoring. (3) To provide UV forecast auxiliary information. (4) To execute UV instruments calibration quality control. Beside of operational works, the following jobs have been done: While the UVI operational forecast with the forecast model of 4th generation keeps on, a parallel UV forecast has been made with a UVI forecast numerical dynamical model system, the 5th generation UVI forecast model, since mid- October of 2010. The performance of this new system is getting improved step by step after data inflow problem solved. This new system is organized as a two tier forecast. The first tier forecast uses the cloudiness simulated with a regional model, MM5. The second tier adds the CWB weather forecast in. This forecast system can remove the bias from subjective forecast and be expected to improve UVI forecast. The data of the UV monitoring system is analyzed. It is shown that the ratio of valid data is quite high. The variation of the observation is stable. The probability of UVI larger than” over-scale” at the stations significantly increased in 2008. Therefore, a positive long-term trend appeared. The proportion of the radiation sustained during noon in daily total amount appears high in winter and low in summer. Probability of UVI larger than hazard –scale as well as UVI≧8 show spatial and inter-annual variability. Climate and weather as well as UVI changed abruptly. Furthermore, meteorological data such as maximum temperature, diurnal temperature range, humidity, cloudiness, and precipitation have been analyzed to explore the causes of monthly UVI anomalies. UV monitoring and forecast data have analyzed. It is shown that UVI forecast performance is quite stable. Furthermore, in order to improving UVI forecasting, meteorological data such as weather map, station temperature and humidity, as well as satellite image have been studied while forecast is fail. All works proposed have been accomplished. A web site of UV monitoring and forecast has been maintained, the content of the raw data and statistics analyzing result of observations, and UV instrument calibration records have been kept and updated by schedule; held scheduled discussion meetings. All these work helps to enhance the UV forecast and monitoring ability in Taiwan.

UVI, Monitoring and forecasting, calibration