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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPACTS OF RISING ATMOSPHERIC CARBON DIOXIDE AND TEMPERATURE ON CROP GROWTH, REPRODUCTIVE PROCESSES, YIELD, AND SEED QUALITY

Location: Chemistry Research Unit

Title: Evapotranspiration: A measurement system and remote-sensing method for regional estimates

Authors
item Heimburg, K - UNIVERSITY OF FLORIDA
item Allen, Leon
item Huber, W - UNIVERSTIY FO FLORIDA

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 5, 2007
Publication Date: N/A

Technical Abstract: A method was developed for making evapotranspiration (ET) estimates based on measured air temperature, remotely sensed surface temperature, and net radiation (Rn). The method was validated from ET measurements made over a pasture near Gainesville using the energy budget--profile Bowen ratio technique. A data acquisition system, air sampling system, and time constant matched humidity, temperature, and radiation sensors were developed to log data and calculate half hour average surface energy budgets. Generally, radiation surface temperatures were not the same as effective heat transport surface temperatures. Because parameters were assumed constant, estimated instantaneous ET was sometimes too high or low, but these errors tended to cancel in estimated cumulative ET. The method was well suited for use with 1-3 hour time resolution satellite data. The method evaluated surface parameters such as moisture availability, required no interpolation for ET estimates between data sets, was adapted to inevitable cloud-caused loss of satellite surface temperatures, and reduced calculation of ET to estimating total positive Rn and duration of positive Rn in a particular period.

Last Modified: 9/20/2014
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