National Airborne Field Experiments for Prediction in Ungauged Basins

Environmental remote sensing has matured significantly over the past two decades as a result of new satellites and intensive airborne campaigns. As such, current remote sensing technology has a huge potential for hydrologic prediction in ungauged basins, through an ability to measure many land surface states, fluxes and parameters that impact on basin prediction. For instance, it is now possible to measure evapotranspiration rates that impact on soil moisture and baseflow, nearsurface soil moisture content that controls rainfall partitioning into infiltration and runoff, snow water equivalent of the snow pack that impacts springtime runoff, vegetation parameters such as leaf area index and greenness that impact on evapotranspiration, land surface elevation and canopy height that impact on runoff routing and evapotranspiration, and so on. However, there are still many unanswered questions that need to be addressed, such as validation of these data products from new sensors, maturing retrieval algorithms, developing techniques for downscaling, and merging remote sensing data with model predictions through the process of data assimilation. To answer these questions and more it is essential that modelling be undertaken in conjunction with field experimentation in well instrumented basins together with intensive ground-based and airborne measurements of the appropriate type and spatial/temporal resolution.