Remotely sensed data can be of great interest for the site selection of astronomical observatories. In particular, candidate sites of the future European Extremely Large Telescope (E-ELT) of 30-60 m diameter from ESO need to be assessed and analytically compared in their observing characteristics. Parameters such as cloud cover and precipitable water vapor which are important for optical and infrared astronomical observations have been assessed with the MEdium Resolution Imaging Spectrometer

more »

... RIS) instrument on the Envisat satellite with a resolution of 1km pixel. A validation of the data was made by comparing MERIS data and in situ measurement available from ESO observatories in Chile, La Silla and Paranal, combined with lower resolution values from the GOES weather satellite. A detailed analysis of daytime cloud cover from 2002 to 2006 at four sites under study both in the northern and in the southern hemisphere for the E-ELT is presented.