1. a ESSIC, University of Maryland , College Park, MD 20742, USA
2. b Raytheon/STSS, Laboratory for Hydrospheric Processes , NASA/GSFC , Greenbelt, MD 20771, USA
3. c Universities Space Research Association , 7501 Forbes Blvd., Seabrook, MD 20706, USA
4. d NASA/GSFC , Laboratory for Hydrospheric Processes , Greenbelt, MD 20771, USA