GEWEX advances understanding of the coupled hydrologic and atmospheric processes on a global scale and applies global water cycle understanding, observations, and models to the problems of climate and water resources around the world. There are three major areas of research within GEWEX: data and assessments, hydroclimatology, and modeling and prediction. Data and assessments are a crucial starting point for expanding knowledge. Hydroclimatology looks at the water cycle and its interaction with the environment and climate system, bringing together many fields of study. Modeling and prediction let researchers examine the mechanisms at work within the water and energy cycles and anticipate future changes in the system.

Four different Panels explore each of the three areas, with GDAP focused on data and assessments, GHP on hydroclimatology, and GASS and GLASS on modeling and prediction.

Within these Panels, GEWEX projects aim at quantifying the hydrologic cycle and energy fluxes by means of global measurements of atmospheric and surface properties; modeling the global water cycle and its role in the climate system; developing the ability to predict variations of global and regional hydrologic processes and water resources and their response to environmental change; and fostering the development of observational techniques, as well as data management and assimilation systems. GEWEX activities involve understanding and modeling land-atmosphere coupling and cloud system processes, global data set development, water resource applications, and the effective use of Earth observations in climate science.


The Water Cycle

Hydrological cycle The water cycle depicted schematically, driven by radiation and energy. Also featured are the atmospheric dynamics that move water and energy around and produce clouds that block the sun, the complex land surface complete with human influences and interactions with the atmosphere, and the surface and sub-surface processes that complete the water cycle (adapted from Trenberth et al., 2007).