Hanna Blanck, University of Iceland, Reykjavik, Iceland, Kristin S Vogfjord, Icelandic Meteorological Offic, Reykjavik, Iceland, Halldor Geirsson, University of Iceland, Faculty of Earth Sciences, Reykjavik, Iceland and Vala Hjorleifsdottir, Reykjavík Energy, Reykjavik, Iceland