Submitted to: Journal of the Atmospheric Sciences
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2017
Publication Date: N/A
Technical Abstract: Water is already a scarce resource in many parts of the world. As the global population continues to grow, the competing demands for fresh water by urban, industrial, and agricultural user will also increase. To ensure there is sufficient water to meet these demands, policymakers, resource managers, and agricultural producers must maximize the effective use of the available water. In turn, achieving this goal is predicated on accurate information regarding crop water use including water loss through evapotranspiration (ET). Due to their highly structured canopy, turbulent transport, thus ET, over vineyards does not necessarily conform to that typically exhibited by other agricultural and natural ecosystems. The Grape Remote sensing and Atmospheric Profiling and Evapotranspiration Experiment (GRAPEX) is an ongoing multi-institution field project in California’s Central Valley to address this knowledge gap. Specifically, GRAPEX seeks to improve our understanding of and ability to monitor the surface energy fluxes, especially ET, over vineyards using remote sensing-based approaches. The study is conducted over a pair of adjacent heavily-instrumented vineyards. The data sets include surface and meteorological conditions, energy fluxes, and profiles of wind velocity, temperature, and moisture within and above the canopy. Additional measurements include airborne imagery. These data have been used to investigate the effects of canopy structure on surface roughness and turbulent flow patterns, the utility of remote sensing-based models (ALEXI/disALEXI) to estimate ET at field scales, and the applicability of correlation-based flux partitioning methods to vineyards. This presentation provides an overview of the GRAPEX project and discusses some of the initial results from the study.