1. Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA
2. Wegener Center for Climate and Global Change and IGAM/Institute of Physics; University of Graz; Graz Austria
3. Department of Earth and Environmental Sciences; Columbia University; New York City New York USA
4. Geophysical Fluid Dynamics Laboratory; National Oceanic and Atmospheric Administration; Princeton New Jersey USA
5. UCAR, Geophysical Fluid Dynamics Laboratory; National Oceanic and Atmospheric Administration; Princeton New Jersey USA