Seite - 390 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 4 Comparison of NOAA forecast data before / after qmap and factor correction, example eastern Germany 4.4. INDICES: SPI Based on observed and bias-corrected forecast data, the SPI was calculated for different aggregation periods. The SPI calculated using only observed data ("certain knowledge") was compared with the SPI obtained by considering different fractions of observed records and NOAA forecasts. Fig. 5 shows results for a 12-month aggregation period for two ground stations in eastern Germany. The SPI calculated using NOAA forecasts reveals a good fit in comparison to the SPI based on measured data and more significantly exhibits the same tendency for upcoming dry periods. 390