摘要
The state of knowledge and outstanding challenges and opportunities in global water cycle observations, research and modeling are briefly reviewed to set the stage for the reasons behind the new thrusts promoted by the World Climate Research Programme (WCRP) as Grand Challenges to be addressed on a 5- to 10-year time frame. Those focused on water are led by the GEWEX (Global Energy and Water Exchanges) project. A number of GEWEX science questions are being brought forward within GEWEX and the WCRP under guidance of the Joint Scientific Committee. Here, we describe what are some imperatives and opportunities for major advancements in observations, understanding, modeling and product development for water resources and climate that will enable a wide range of climate services and inform decisions on water resources management and practices.