Lloyd W. Gay. Professor, Watershed Management: Renewable Natural Resources,
Department of Plant Sciences. Ph.D., Duke University. (25% Research in Plant Sciences; changing to 100% Renewable Natural Resources on 1-October-1996).

• Office: Biological Sciences East, #306 (621-7268)
• e-mail: lgay@ag.arizona.edu

Microclimatology and plant water use.

My research interests focus upon the processes that control the exchange of thermal energy between the atmosphere and the surface of the earth. This exchange has important implications for surface microclimate, with concurrent effects on plant productivity, stress and water use. The crucial problem is the partitioning of absorbed radiant energy into latent energy (evapotranspiration or ET) and sensible heat (convection). The partitioning process is affected by the general climatic regime and by surface conditions such as moisture availability and type of vegetation.

My research is experimental, and can be classified into three groups: (1) instrumentation and xperimental design; (2) modeling of evapotranspiration from irrigated crops; and (3) modeling of evapotranspiration from wildland vegetation. The research has led to my development of improved, battery-powered, ET instrumentation suitable for unattended operation at remote locations. The "AZET Bowen ratio" system works best over smooth, transpiring canopies of irrigated crops, while the "One-Propeller Eddy Correlation (OPEC)" system works best over rougher canopies of slowly transpiring wildland vegetation. Availability of measurement systems such as these makes it feasible to experimentally determine thermal energy exchange between plant canopies and the atmosphere in order to evaluate and refine linkages that exist between microclimate, water use, climate change, plant development and growth.

Gay, L. W. 1988. A portable Bowen ratio system for ET measurements. Proc., Nat. Conf. Irrig., Drainage. Pp. 625-632. ASCE, NY 345 E. 47th St., New York, NY 10017.

Stewart, J. B., and L. W. Gay. 1989. Preliminary modeling of transpiration from the FIFE site in Kansas. Agric., Forest Meteor. 48:305-310.

Dugas, W. A., L. J. Fritschen, L. W. Gay, A. A. Held, A. D. Matthias, D. C. Reicosky, P. Steduto and J. L. Steiner. 1991. Bowen ratio, eddy correlation, and portable chamber measurements of sensible and latent heat flux over irrigated spring wheat. Agric., Forest Meteor. 56:1-20.

Gay, L. W. 1992. Energy budget measurements in irrigated alfalfa: a case study of advection in an arid region. Wetter und Leben 44:125-137.

Blanford, J. H., and L. W. Gay. 1992. Tests of a robust eddy correlation system for sensible heat flux. Theor., Appl. Climatol. 46:53-60.

Gay, L.W., R. Vogt, Ch. Bernhofer and J.H. Blanford. 1996. Flux agreement above a Scots pine plantation. Theor., Appl. Climatol. (In press, vol. 53).

Gay, L.W., R. Vogt and A. Kessler. 1996. The May-October energy budget of a Scots pine plantation at Hartheim, Germany. Theor., Appl. Climatol. (In press, vol. 53).