1. a University of Athens , Department of Applied Physics , Building PHYS‐V, GR‐15784, Athens, Greece
2. b School of Chemical Engineering , National Technical University of Athens , Zografou Campus, GR‐15780 Athens, Greece
3. c Institute for Space Applications and Remote Sensing , National Observatory of Athens , Metaxa & Vas. Pavlou St, Penteli, GR‐15236 Athens, Greece