Submitted to: Handbook of Weather Climate and Water
Publication Type: Book / Chapter
Publication Acceptance Date: 5/20/2002
Publication Date: 1/1/2003
Citation: Kustas, W.P., Moran, M.S., Norman, J.M. 2003. Evaluating the spatial distribution of evaporation, Chapter 26 In Handbook of Weather, Climate and Water: Atmospheric Chemistry, Hydrology and Societal Impacts, Eds. T.D. Potter and B.R. Colman, John Wiley & Sons, Inc. p. 461-492. Interpretive Summary: Water loss from soil and plant surfaces influences the large-scale circulation of the Earth's atmosphere, affects the soil moisture available for plant growth, and can regulate global climate changes. This vast range of effects makes it of vital environmental interest. In recent decades, efforts have been focused on the use of satellite-based images to map the flow of heat and water through the soil, vegetation and atmosphere. This chapter identified a multitude of techniques using satellite images to provide operational and accurate information about water loss from fields, regions and continents. The major obstacles to providing such information are the limitations of currently orbiting sensors and the lack of large scale field research conducted in different climatic regions. This review provides a foundation for planning future satellite sensors and platforms and for guiding government agencies and universities in funding field studies.
Technical Abstract: This chapter provides an overview of techniques for evaluating evaporation from local to regional scales. Remote sensing data is seen as having great potential for providing key surface boundary information in a spatially distributed manner and at regional scales, including surface radiation fluxes, vegetation cover, surface temperature and surface moisture conditions. Attempts have been made to develop physically-based models which explicitly treat the soil and vegetation interactions with the atmosphere. However, many of these approaches also require daily remotely sensed data as well as meteorological data for computing the surface fluxes over the course of a day. This has led to the development of soil-vegetation-atmosphere (SVAT) schemes that are linked to atmospheric models which in principle do not require remote sensing or meteorological inputs at every time step. These have the greatest potential for operational and regional applications. However, with optical data, atmospheric attentuation and clouds present difficult problems for frequent observations of the region of interest. In contrast, microwave observations have atmospheric and cloud penetration, high spatial resolution with radar, and day/night acquisitions.