W. D. Hively, USGS Eastern Geographic Science Center, Reston, VA, United States, Brian Thomas Lamb, CUNY City College, New York, NY, United States, Craig S.T. Daughtry, USDA ARS, Hydrology & Remote Sensing Lab, Beltsville, MD, United States and Miguel Quemada, Universidad Politécnica de Madrid, CEIGRAM/Agricultural Production, Madrid, Spain