[1] George Mason Univ, Inst Global Environm & Soc, Calverton, MD 20705 USA
[2] European Ctr Medium Range Weather Forecasts, Reading RG2 9AX, Berks, England
[3] Univ London Imperial Coll Sci Technol & Med, Grantham Inst, Reading, Berks, England
[4] Univ Reading, Dept Meteorol, Reading, Berks, England
[5] Ctr Ocean Land Atmosphere Studies, Calverton, MD USA
[6] Max Planck Inst Meteorol, Hamburg, Germany
[7] Univ Reading, Walker Inst, Reading, Berks, England