## 1 Introduction  
Acquiring accurate measurements of crop consumptive water use in the form of evapotranspiration (ET) is increasingly important as demands for water resources drastically shift under a changing climate. This acquisition is particularly critical in the Central Valley of California, where competition for diminishing water resources is increasing due to prolonged periods of severe drought, population growth, and increasing demands from municipalities and industry [1]. Such are the demands that the state enacted the Sustainable Groundwater Management Act (SGMA), an effort to monitor and regulate the over-pumping of vulnerable groundwater basins. Considering these regulations, California-based commodity groups continue to have a vested interest in the sustainability of agriculture in the state, which is valued at USD 50 billion per year [2; 3] and produces more than 400 different commodities. This interest has produced partnerships with federal and state agencies and universities to promote sustainable practices through the research and development of emerging state-of-the-art technologies focused on promoting water use efficiency. Two such projects include the Grape Remote Sensing Atmospheric Profile Evapotranspiration eXperiment (GRAPEX; [4]) and the Tree crop Remote sensing of Evapotranspiration eXperiment (T-REX), where the priority is to improve irrigation efficiencies through satellite-derived ET estimates for wine grapes and almond orchards, respectively. GRAPEX began in 2013 and continues with nine vineyards being monitored with micrometeorological instrumentation located throughout the Central Valley and Sonoma County, California. T-REX began in the spring of 2021 and continues to support the monitoring of three almond orchards located near Sacramento and Fresno, California. Much has been learned during the GRAPEX project, which includes ground-based micrometeorological/biophysical-focused work [4; 5; 6; 7; 8], the utilization of remotely piloted aerial vehicles (RPAVs) for an improved understanding of spatial dynamics within vineyards [9; 10; 11; 12; 13; 14], and the evaluation of satellite-based ET estimates, both retrospectively [15; 16; 17; 18] and in real-time [19], to promote ingestion into irrigation management dashboards. Similar work is currently underway in the T-REX project. Although work related to these projects has advanced our understanding of specialty crop dynamics as it relates to water use, questions remain. One of particular interest is the partitioning of ET, used as a measure of consumptive water use, into individual contributions of evaporation (E) and transpiration (T) in these vineyard/orchard systems, which are represented by distinct inter-row (denoted by cover crop or bare soil depending on management practice and time of year) and row (crop canopy). In water-limited regions such as California, some irrigation strategies will likely focus on reducing water loss from E rather than T since vegetation T is linked to crop biomass production [20; 21; 22]. Many ET partitioning techniques exist (detailed review provided in [23]), with recent advancements developed to curb laborious measurements, expensive sensors, and the need for a priori site knowledge [24; 25; 26]. Despite advancements, these approaches cannot be inferred or spatially distributed across large landscapes. Such a solution requires the utilization of remote sensing, whether from RPAVs or satellite imagery, and an approach that explicitly accounts for soil (E) and canopy (T) contributions to ET. The two-source energy balance (TSEB) model [27] offers these capabilities by partitioning a thermal infrared (TIR) signal into canopy and soil temperatures and solving the surface-energy budget for the soil, vegetation, and combined systems associated with a mixed pixel. TSEB has been applied across many surfaces [28; 29; 30; 31; 32; 33; 34; 35], including vineyards, with good fidelity [9; 10; 12; 34; 36; 37].