1. Johannes Gutenberg Univ. Mainz; Earth System Science Research Center; Geographic Institute; Johann-Joachim-Becher-Weg 21 55128 Mainz Germany
2. Univ. of Frankfurt, Institute of Geoscience; Altenhöferallee 1 60438 Frankfurt am Main Germany
3. University of Berne, Geographic Institute; Hallerstrasse 12 3012 Berne Switzerland