[1] Univ Reading, Natl Ctr Atmospher Sci, Reading, Berks, England
[2] Univ Reading, Dept Meteorol, Reading, Berks, England
[3] Stat Norway, Res Dept, Oslo, Norway
[4] Oslo Ctr Res Environm Friendly Energy, Oslo, Norway
[5] CICERO Ctr Int Climate Res, Oslo, Norway