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Estimating soil water evaporation using radar measurementsField studies were conducted to evaluate the application of radar reflectivity as compared with the shortwave reflectivity (albedo) used in the Idso-Jackson equation for the estimation of daily evaporation under overcast sky and subhumid climatic conditions. Soil water content, water potential, shortwave and radar reflectivity, and soil and air temperatures were monitored during three soil drying cycles. The data from each cycle were used to calculate daily evaporation from the Idso-Jackson equation and from two other standard methods, the modified Penman and plane of zero-flux. All three methods resulted in similar estimates of evaporation under clear sky conditions; however, under overcast sky conditions, evaporation fluxes computed from the Idso-Jackson equation were consistently lower than the other two methods. The shortwave albedo values in the Idso-Jackson equation were then replaced with radar reflectivities and a new set of total daily evaporation fluxes were calculated. This resulted in a significant improvement in computed soil evaporation fluxes from the Idso-Jackson equation, and a better agreement between the three methods under overcast sky conditions.
Document ID
19880060216
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sadeghi, Ali M. (USDA Beltsville, MD, United States)
Scott, H. D. (Department of Agriculture Beltsville, MD, United States)
Waite, W. P. (Arkansas, University Fayetteville, United States)
Asrar, G. (NASA Headquarters Washington, DC United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1988
Publication Information
Publication: IEEE Transactions on Geoscience and Remote Sensing
Volume: 26
ISSN: 0196-2892
Subject Category
EARTH RESOURCES AND REMOTE SENSING
Distribution Limits
Public
Copyright
Other