Using ASTER satellite and ground-based surface temperature measurements to derive supraglacial debris covere and thickness patterns on Miage Glacier (Mont Blanc Massif, Italy)

High resolution in situ surface temperature measurements of supraglacial debris cover on Miage Glacier, Mont Blanc Massif, Italy, are compared to ASTER-derived surface temperature data (TIR band, acquisition time 10:40 UTC+ 1:00 on 01-08-2005, in the frame of GLIMS project). Spatial patterns of surface temperature and supraglacial debris cover distribution revealed in the two datasets are described. The ground- and remotely sensed temperatures correlate strongly over continuously debris-covered areas (r=0.8), while on partially debris-covered ice (i.e. crevassed areas and ice cliffs) the correlation is weaker (r=0.69 over the whole glacier tongue). A map representing the spatial distribution and thickness of the debris cover is derived from the ASTER surface temperature data using debris-surface temperature-thickness relationships (r=0.8), calculated in 100 m elevation bands. Over < 1 day, surface temperature is influenced by surface meteorological conditions, shading, roughness and elevation; over period of > 1 week, debris thickness is the primary control. Both ground and remotely sensed data predict well the thick debris cover at the terminus and its upstream decrease, and broad cross- and along-glacier patterns of debris thickness are revealed in the ASTER data, e.g. moraines, crevassed areas. Finer details in the debris thickness distribution are not revealed in the ASTER data, due mainly to the coarse 90 m resolution of the thermal-band imagery.