Development of GIS models via optical programming and python scripts to implement four empirical methods of reference and actual evapotranspiration (ETo, ETa) incorporating MODIS LST inputs

The purpose of the study was the development of GIS models implementing two empirical methods of reference evapotranspiration (ETo), namely FAO-56 Penman-Monteith (FAO-56 PM) and Hansen, and two empirical methods of actual evapotranspiration (ETa), namely Turc and Corrected Turc (CT). GIS software (ArcMap 10.6) model builder environment was used for model-implementation, though the models could be easily transferred in relative software types (e.g. QGIS, ERDAS). The affordances of the presented models are flexibility and applicability to any study area (using the corresponding raster images of remote-derived or interpolated data as inputs), cell-by-cell calculations (estimates for the continuum of space) and dual representation of the empirical formulae; as optical models and as python scripts.Models’ application has been made on Peloponnese, Greece, a complex Land Use Land Cover (LULC) Mediterranean area, engaging MODIS LST Terra day and night inputs which have been acquired from USGS Earth Explorer and NASA EARTH DATA platforms. MODIS LST day and night products have been proved satisfactory proxies of maximum and minimum values (respectively) of local near surface air temperature (Tair). Alternatively, considering overpassing local time for each study-area Aqua or any other satellite products could be used as inputs. Furthermore, 8-day composites of MODIS net evapotranspiration (ET) (MOD16A2V6) have been acquired and compared to model outputs for different time scales and ET types. Corrected Turc and Hansen formulae exhibited estimates satisfactorily close to MODIS ET for different time scales. Overall, the proposed models have been proved time-saving and useful tools for water management applications that can be utilized by inexperienced to advanced users.