Over the past decade the Global Energy and Water Cycle Experiment (GEWEX) has coordinated the development of Continental Scale Experiments (CSEs) that have contributed to advances in prediction capabilities through process and modeling studies, and data set development. The first experiment, the GEWEX Continental-scale International Project (GCIP), focused its efforts on the data rich Mississippi River Basin. It concentrated on closing regional water and energy budgets and improving land surface models for prediction and data assimilation. BALTEX (Baltic Sea Experiment), carried out in the drainage basin of the Baltic Sea, also focused on model development and data set development but it included ocean-atmosphere interactions. The GEWEX Asian Monsoon Experiment (GAME), with studies in four distinct climate regimes in eastern Asia, contributed to a better understanding of the role of land in the monsoon system. The LBA (Land Biosphere-Atmosphere Program) and MAGS (Mackenzie GEWEX Study) have improved the understanding of tropical and cold region land processes respectively. Individually and collectively these experiments have contributed to a more complete understanding of the role of land in the global climate system and provided a number of unique data sets to facilitate model development. New initiatives, that are or will become CSEs or affiliates, are underway in Australia (Murray Darling Basin) and South America (La Plata Basin)

Future activities are expected to emphasize more cross-region integration, greater exploitation of satellite data, significant advances in the understanding of seasonal predictability, and experimental products of more relevance to users. Increased scientific and data base integration are being realized through the Coordinated Enhanced Observing Period (CEOP) which started in the summer of 2002. This presentation will highlight the scientific insights and developments that have arisen through these large scale experiments. It will conclude with comments about some of the scientific challenges that will face these Continental Scale Experiments during the second phase of GEWEX.