Langzeitvariabilität der globalen und direkten Solarstrahlung für Solarenergieanwendungen

Solar energy takes a leading role amongst renewable energies. For
the planning of new solar power plants the ISIS data set
(Irradiance at the Surface derived from ISCCP cloud data) has been
generated in this study. For the first time a data set contains
global and direct normal irradiance and is therefore applicable for
all kinds of solar power plants. The ISIS data set consists of 21
years of three-hourly irradiances (1984-2004), which have been
derived from International Satellite Cloud Climatology Project
(ISCCP) cloud data with the method that has been developed for this
study. On the basis of the ISIS data set long-term variability of
global and direct normal irradiance has been investigated. The
average year to year variability of global irradiance within an
ISIS grid box of 280 km x 280 km is 3%, the variability of direct
normal irradiance of 7% is more than twice as high. Through volcano
eruptions yearly averages of direct normal irradiance are reduced
by 19% on average, yearly averages of global irradiance are only
reduced by 3%. Global irradiance shows no trend within the analysed
time span, but direct normal irradiance increases on average by
0.63% per year. As cause of these trends stratospheric aerosol and
changes in cloud amount and optical thickness of clouds could be
identified.