Open AccessLong-term evapotranspiration estimates in the Walnut River Watershed in Kansas.
Author(s) -
R. L. Coulter,
Gerard E. Klazura,
Barry M. Lesht,
M. L. Wesely
Publication year - 1999
Language(s) - English
Resource type - Reports
DOI - 10.2172/12043
Subject(s) - evapotranspiration , environmental science , watershed , satellite , remote sensing , scale (ratio) , meteorology , sensible heat , flux (metallurgy) , water vapor , hydrology (agriculture) , computer science , geology , geography , cartography , engineering , ecology , geotechnical engineering , machine learning , biology , materials science , metallurgy , aerospace engineering
This project focuses on improving and testing a simple method for using reflectance data obtained from satellites to infer the effects on evapotranspiration of variations in soil moisture availability. The major advantage to the method, which is based on the parameterization of subgrid-scale surface fluxes (PASS) model (Gao 1995; Gao et al. 1998), is that it can be applied to areas having diverse surface characteristics where direct surface flux measurements either do not exist or are not feasible and where meteorological data are available from only a limited number of ground stations. The emphasis of the PASS model is on improving (1) methods for using high-resolution satellite remote sensing data to derive the essential parameters for individual types of surfaces overlarge areas, (2) algorithms for describing the interactions of near-surface atmospheric conditions with surface processes, and (3) algorithms for computing surface energy and water vapor flux at a scale close to the size of a satellite pixel. An operational modeling system is being developed. Testing of the system is accomplished by applying it to the Walnut River Wak-shed (WRW), instrumented watershed of moderate area (5,000 km{sup 2}) located just east of Wichita, Kansas. Data from field experiments such as the intensive field campaign in 1997 by the Cooperative Atmosphere-Surface Exchange Study (CASES) and from routine operation of the Atmospheric Boundary Layer Experiments (ABLE) in the WRW are used to evaluate the ability of the PASS model to estimate accumulated water loss over a growing season. The research goals of the project areas follow: (1) Improve the existing satellite-data interfacing modules, especially the parameterization of soil moisture availability and water vapor flux; (2) Apply and evaluate the methods by using measurements at ground stations distributed within the WRW; and (3) Develop an operational version of the modeling system, and apply it to derive long-term evapotranspiration estimates at the WRW