On the intraday resampling of time-integrated values of solar radiation

摘要: Measurements of solar downwelling radiation are made at ground level by integrating the received energy during an integration time, e.g., 1 h. The sampling is usually equal to time. In this way, one constructs time series integrated values. Further processing such measurements often requires oversampling data in order obtain values a higher temporal sampling. For example, assessment direct irradiation normal incidence from hourly beam on horizontal surface resampling resolution, minute, account precisely position dynamics hour. Many interpolation techniques found literature for processing. They mainly based standard signal as nearest neighbours, linear, cubic or spline interpolation. This communication deals with transformation and focuses 1-h 15-min 1-min Several used their merits discussed. Resampling can be performed values; we show that better results attained transformed values, clearness clear-sky indices, then reversing resampled indices into irradiation. Furthermore, express consistency property: average oversampled should original series. We property not respected usual techniques. error small but it concentrated high frequencies therefore has impact computation incidence. may noticeable different time-scales: intraday, day, month, year. Our theoretical expectations confirmed experimentation high-quality measured BSRN station Payerne, Switzerland. serves reference. these every 15 min h, Linear interpolations applied either index. Results compared respect assessed. differences summarized terms root mean square error, correlation Kolmogorov-Smirnov test discrepancies cumulative distribution functions. Fourier analyses assess power spectral density and, therefore, estimation errors approaches. Unsurprisingly, 1) index more accurate than irradiation, 2) clear overcast skies intermediate skies. relative sum term ranges between 3 % 6 subsequent 9 %.