Geoscience Reference
In-Depth Information
Challenges and Opportunities in Water Cycle Research:
WCRP Contributions
Kevin E. Trenberth
•
Ghassem R. Asrar
Received: 1 May 2012 / Accepted: 10 November 2012 / Published online: 4 December 2012
Springer Science+Business Media Dordrecht 2012
Abstract 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.
Keywords Global water cycle
Hydrological Cycle
WCRP
Precipitation
GEWEX
Water resources
Climate Change
Climate extremes
1 Introduction
Driven mainly by solar heating, water is evaporated from ocean and land surfaces,
transported by winds, and condensed to form clouds and precipitation which falls to land
and oceans. Precipitation over land may be stored temporarily as snow or soil moisture,
while excess rainfall runs off and either forms streams and rivers, which discharge the
freshwater into the oceans, or infiltrates into the soil and percolates to depths to re-charge
the underground aquifers thereby completing the global water cycle (Trenberth et al.
2007a
; Fig.
1
). Associated with this water cycle, energy, salt within the oceans, and
nutrients and minerals over land are all transported and redistributed within the Earth
