TOPS operates in combination with a vegetation canopy water balance model to predict evapotranspiration, soil moisture, and crop water stress in agricultural regions. The prototype system currently operates within California's Napa Valley winegrowing region, and is designed to help viticulturists maintain specified target levels of water stress in their vines. Vineyard irrigation and resulting water status affect several key cropping aspects, including ripening rate, fruit composition, yield, and susceptibility to infestation or disease. Water deficits strategically imposed by deficit irrigation can be used for canopy regulation and water conservation. Remotely sensed vegetation index imagery is combined with growing-degree-day calculations to evaluate the transpiration crop coefficient thru the leaf area index. These data are combined with meteorological data and potential evapotranspiration (California Dept. Water Resources), soils data (US Dept of Agriculture), and 7-day National Weather Service forecasts. The system operates on a 24-hr timestep to simulate current and projected soil moisture status, current and projected leaf water potential, projected date of crop stress onset, and can be used to generate recommended irrigation quantities.

Publications and additional information are available on the Vintage Project website. NASA Ames researchers are continuing to develop TOPS and the Ecocast system as a tool for monitoring and forecasting environmental parameters that affect crop productivity and quality. To obtain additional information, or to inquire about collaborating with NASA Ames, please contact Dr. Rama Nemani.