1. Engineering Systems and Environment, University of Virginia, Charlottesville, VA 22903, USA
2. GESTAR II, University of Maryland Baltimore County, Baltimore, MD 21250, USA
3. Hydrological Sciences Laboratory, National Aeronautics and Space Administration Goddard Space Flight Center, Greenbelt, MD 20771, USA
4. Earth Science Division, National Aeronautics and Space Administration Goddard Space Flight Center, Greenbelt, MD 20771, USA