Inquiries into microclimatological patterns and processes have been inhibited by difficulties in determining micro-scale variations in heat and moisture transfers. Among the most important variables are transfers of water vapor through evaporation and transpiration from ground surfaces and vegetation into the air. Lysimeters have been developed to directly measure evapotranspiration, but these machines are large, stationary, expensive, and capable only of averaging readings over the area that they cover. This collaborative research project will refine and test a set of minilysimeters to measure spatial variations in the transfer of heat and moisture. Three continuously weighing, portable minilysimeters will be designed and tested in a carefully controlled experiment that will compare their measurements with records obtained using three alternative microclimatological approaches. This project will determine the extent to which small, portable minilysimeters can be used to accurately measure evapotranspiration in a variety of different sites. These tests will help ascertain the conditions in which these instruments will be useful and the confidence with which the data that they collect can be used. Because of the potential for using instruments of this type to provide heretofore unavailable information about micro-scale spatial variability in heat and moisture transfer, the project should contribute significantly toward advancement of microclimatological research.
