PROGRAM TITLE:	Water and Energy: Atmospheric, Vegetative and 
Earth  Interactions (WEAVE)
ACTIVITY STREAM:	Process, Model, Data, Observe, Assess
SCIENCE ELEMENT:	Climate and Hydrologic Systems, Ecological 


SCIENTIFIC MERIT: The distribution and fluxes of water between the 
atmosphere and underlying surfaces as mediated by the biota are key 
determinants of regional and global climate.  Water serves as the primary 
conduit of energy transfer in the overall earth system.  Variations and long-
term changes in climate are both the result of and result in changes in the 
ways water is integrated by geological, biological and atmospheric systems. 
Characteristics of the surface affect the evolution of water distribution 
through a variety of processes such as evapotranspiration, surface radiation, 
energy fluxes, precipitation, and surface and subsurface water flow.  
Vegetation is one of the principal variables affecting land surface properties, 
water flux and, ultimately, regional and global hydrologic processes. Of 
particularly high priority to the overall Global Change Program is reducing 
uncertainty in climate models which requires a better understanding of the 
role that clouds play in key climate processes. Energy and water are also 
intricately woven in governing biogeochemical cycles. The interactions 
among the atmosphere, earth and biosphere are complex and further 
complicated by the range in spatial scales at which these interactions occur. 
The response and contribution of each "sphere" to the dynamics of the others 
must be understood in order to describe and understand the global hydrologic 
cycle and ultimately to predict, or to assess the potential for, global change. 

WEAVE combines three NSF programs,  Continental Hydrologic Process, 
Water-Energy-Vegetation  and the Role of Clouds, Energy and Water in 
Global Climate Change, in order to gain a better understanding of energy and 
water in climate processes and to clarify how atmospheric, surface hydrologic, 
and biotic processes maintain the global energy balance and feedback to the 
overall climate system. A key objective of the inter-disciplinary research 
supported by WEAVE will be to find ways to overcome scale disparity among 
the disciplinary fields so that regional and global characteristics can be 
determined. WEAVE will provide the basis for understanding potential 
impacts of human activities on the hydrological cycle and climate system. 
STAKEHOLDERS:  WEAVE links to both international and national (multi-
agency) programs directed at understanding global energy and water cycles. 
WEAVE will be NSF's principal contribution to the Global Energy and Water 
Cycle Experiment (GEWEX) under the WMO's World Climate Research 
Program and a major component of IGBP's Biological Aspects of the 
Hydrological Cycle (BAHC) and Global Change and Terrestrial Ecosystems 
(GCTE). In addition, WEAVE will contribute to land and water management 
programs in the Corps of Engineers, DOI, USDA, FEMA, EPA and related state 

POLICY RELEVANCE:  Water plays a central role in the evolution and health 
of ecosystems and climate processes. Water will also be the focus of national 
and international policy decisions in the near term (e.g., the UNCED 
Desertification Convention) and beyond.  Understanding the physical and 
biological processes that govern the distribution of water will be essential as 
input for economic planning and decisions relating to agriculture and 
forestry, desertification, energy needs, and biodiversity as well as the basis for 
understanding and eventually modeling and predicting long-term climate 
and global change.

Scott Collins, Ecological Studies Program Director
Pam Stephens, Large Scale Dynamic Meteorology Program Director
Doug James, Hydrological Sciences Program Director