摘要：The patterns of daily, monthly and seasonal solar irradiance in the three southernmost provinces of Thailand were investigated. Knowledge of these patterns can help predict future patterns of solar radiation falling on the surface of the earth. Daily solar irradiance observations collected from three surface stations in southern Thailand during one and half years were analysed. A natural cubic spline method was applied to describe the seasonal patterns present in the annual time series of the daily observations. The method, together with an optimum number of knots and their proper placement applied to the observations, yielded quite acceptable fits in describing the seasonal pattern of solar radiation observations. A noticeable feature of the models is the bimodal solar radiation pattern. Pattani province recorded a higher mean amount of solar radiation (450.42 Wm2) relative to the other two provinces. These findings will be essential to stakeholders in the design of solar energy systems since solar irradiance is particularly significant for planning the processes of power plants which convert renewable energy into electricity.
