Satellite based measurements of the planet’s ozone distribution are being conducted in a routine manner from European space crafts since about 1995 when ENVISAT – the largest environmental satellite ever – was put into orbit. Today, the GOME-2 instrument on board of Europe’s spacecraft Metop-A continuously provides ozone data around the globe. The data are being assimilated at DFD into complex so-called Chemical-Transport Models to derive a comprehensive picture of the ozone distribution.