1. a Laboratory for Global Remote Sensing, Department of Geography , University of Maryland , College Park, Maryland, 20742, U.S.A
2. b Institute for the Study of Earth, Oceans and Space, Science and Engineering Building, University of New Hampshire , Durham, New Hampshire, 03824, U.S.A
3. c Commission of the European Communities, Joint Research Center, Institute for Remote Sensing Applications, Ispra Establishment , T.P-.440, Ispra, Varese, 21020, Italy
4. d Applications Division, Canada Center for Remote Sensing , 1547 Merivale Road (4th Floor), Ottawa, Ontario, K1A 0Y7, Canada
5. e US Department of the Interior , EROS Data Center , Sioux Falls, South Dakota, 57198, U.S.A
6. f UCAR , P.O. Box 3000, Boulder, Colorado, 80307, U.S.A