Application of C and Ku-Band scatterometer data for catchment hydrology in northern latitudes

Spatially continuous soil moisture information is on high demand globally. A database which is available from active microwave data (ERS scatterometer, C-band, 50 km) has been assessed over two large basins (Mackenzie and Lena) in northern latitudes. This information was combined with snowmelt patterns which can be derived based on diurnal thaw-refreeze of the snow cover from a further scatterometer (Quikscat, Ku-band, 25 km). Relative soil water information has been averaged over each basin and compared to discharge measurements for the summer periods 1996-2000. A correlation (logarithmic function) of 0.78 is observed for the Lena basin. The Mackenzie is much more complex and thus the relationship is less obvious. This is also reflected in the snowmelt data. Whereas 80% of basin area undergoes melting at the same time in the Lena basin in 2000, at maximum 40% can be observed for the Mackenzie during the same year. Maximum runoff in the Lena basin is observed when snowmelt ceases for the entire basin. This is delayed by three weeks for the Mackenzie although increased runoff can be observed already after 70% of the basin is snow-free.