Seasonal H2O and CO2 ice cycles at the Mars Phoenix landing site: 1. Prelanding CRISM and HiRISE observations - Cull, Selby; Arvidson, Raymond; Mellon, Michael; Wiseman, Sandra; Clark, Roger; Titus, Timothy; Morris, Richard V.; McGuire, Patrick (Journal of Geophysical Research E: Planets, 2010)