School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, USA

now at: Biosphere 2, University of Arizona, Tucson, AZ, USA

Earth and Sun Systems Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA

Earth and Sun Systems Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA

Earth and Sun Systems Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA

School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, USA

now at: Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA

School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, USA