Marine phytoplankton represents the basis of the marine food web and plays as biological pump an important role within the global carbon cycle. This article presents the method PhytoDOAS which enables to retrieve from satellite data not only the general global distribution of phytoplankton, but also by using highly spectrally resolved data their composition in dependence to different functional groups of phytoplankton. From these temporally highly resolved global maps it can be derived how much CO2 is fixed to organic carbon, and how much oxygen and food is produced by marine microalgae. Since different algae groups have different functions within the marine ecosystem and carbon cycle, the maps will help a lot to observe their temporal changes and to estimate the effect of climate change.