ROBERT JAMES GURNEY Director of NERC Environmental Systems Science Centre University of Reading

 
"Water, Water Everywhere?"

   Abundant water at the Earth's surface in all three phases (ice, water, water vapour) is one of the key factors that makes the Earth unique in the Solar System.  Water is essential for life, and is a key component of the Earth's energy and carbon cycles.  Despite this, there are still great uncertainties in our knowledge of the exchanges of water.  The distribution of water vapour in the atmosphere can largely be determined from the atmospheric dynamics, but the phase changes via processes of condensation and  evaporation, that result for instance in clouds, are not always so easily modelled.  At the land surface, local heterogeneity means that the coupling of the terrestrial and atmospheric components of the water cycle is only known imperfectly, and leads to further uncertainties of the impacts of changes in land surface characteristics.  Remote sensing has often been suggested to improve our knowledge of the hydrological cycle, but the benefits promised have only partly been met, and there are areas where little progress has been made.  Only by using observations with global models will the uncertainty be reduced.  New global models with very high spatial resolution, new observations and new ways of using the latest computing technology to bring these together should finally allow progress to be made with understanding this key component of the Earth system.

 

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