The estimation of the spatial and temporal variability of the hydrologic and energy budgets of the land surface is a central objective of studies such as the GEWEX Continental Scale International Project (GCIP), and is crucial for improved climate simulation, numerical weather prediction and water resources management. Macroscale hydrological modeling is a powerful tool with which to develop predictive understanding of the large scale dynamics of these budgets. However, hydrological modeling at continental scales and beyond is greatly hindered by the scarcity of land surface observations needed to drive the models.

Remote sensing promises to revolutionize large scale hydrological modeling by providing an alternative to the use of ground observations that historically have been the sole model forcings. The challenge is to design hydrologic model structures and remote sensing methodologies that make best use of the largely untapped potential of satellite observations for water resources management during the EOS-era.