1. Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado
2. Cooperative Institute for Research in Environmental Sciences, and Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado
3. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
4. Program in Atmospheres, Oceans, and Climate, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts