2011 Annual Report
1a.Objectives (from AD-416)
Develop an inexpensive method for real-time, remotely-accessible measurement of vineyard-scale evapotranspiration and vine water use.
1b.Approach (from AD-416)
A field based surface renewal system will be used to estimate vine and whole vineyard water use. The work will involve developing a self-calibrated, inexpensive, user-friendly surface renewal system for use in vineyards.
This agreement was established in support of objective 3 of the in-house project, the goal being to develop sustainable water management practices for vineyards. The goal of this project is to develop an inexpensive method for real-time, remotely-accessible measurements of vineyard-scale evapotranspiration & vine water use. Micrometeorological methods and ecosystem-scale energy and gas flux measurements have become increasingly important in soil, crop, and environmental sciences. For many scientists without formal training in atmospheric science, these techniques are relatively inaccessible. Eddy covariance, surface renewal, and other flux measurement methods require an understanding of boundary layer meteorology and extensive training in instrumentation and multiple data management programs.
ARS scientists at Davis, CA, developed a new tool to improve access to flux measurement methods for agricultural and environmental research scientists. It is an open-source turnkey data logger program that performs flux data acquisition and post-processing. The new program returns to the user a simple data table with the corrected fluxes and quality control parameters. Prior to the development of this program, researchers had to shuttle between multiple processing programs to obtain the final flux data. Different versions of the program are available to meet various research needs and instrumentation configurations. We are continuing to develop the documentation for the program. At present the program provides instrumentation information and wiring diagrams to assist the researcher with flux tower installation.
The programs are currently deployed in field experiments for the UC Davis Atmospheric Science Dept (UCDASD) and the CA Dept of Water Resources (DWR). UCDASD has 10 evapotranspiration (ET) measurement stations running the program in rice, winegrape vineyard, and alfalfa crop fields. CA DWR has 16 ET measurement stations running the program in rice, irrigated pasture, almond, walnut, peach, lemon, avocado, corn, and raisin vineyard crops.
Tools will continue to be developed to improve access to micrometeorological methods. These efforts include a software package for R, the statistical computing program that is increasing popular among environmental scientists. We intend to publish information about the package a statistical computing journal. An internet resource for collecting and categorizing web-based information about flux measurement materials and methods is planned. We will unveil our new tools to the scientific community at the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America International Annual Meeting in October.
Significant progress has also been made on revisiting the theoretical calculations (i.e. Van Atta equations) that drive Surface Renewal estimates of water flux from agricultural surfaces. Until now, surface renewal relied on Eddy Co-Variance for calibration and our updated theoretical calculations have all but eliminated the need for this calibration. This work resulted in an invited manuscript submission to Boundary Layer Meteorology.