International Journal of Geo-Information Article Reference Evapotranspiration (ETo) Methods Implemented as ArcMap Models with Remote-Sensed and Ground-Based Inputs, Examined along with MODIS ET, for Peloponnese, Greece Stavroula Dimitriadou and Konstantinos G. Nikolakopoulos * Department of Geology, University of Patras, 26504 Rion, Greece;
[email protected] * Correspondence:
[email protected]; Tel.: +30-261-099-759-2 Abstract: The present study develops ArcMap models to implement the following three methods: FAO-56 Penman–Monteith (FAO PM), Hargreaves–Samani (HS) and Hansen, with the former used as a reference. Moreover, three models implementing statistical indices (RMSD, MB, NMB) are also created. The purpose is threefold, as follows: to investigate the variability in the daily mean reference evapotranspiration (ETo) for the Decembers and Augusts during 2016–2019, over Pelopon- nese, Greece. Furthermore, to investigate the agreement between the methods’ ETo estimates, and examine the former along with MODIS ET (daily) averaged products. The study area is a complex Mediterranean area. Meteorological data from sixty-two stations under the National Observatory of Athens (NOA), and MODIS Terra LST products, have been employed. FAO PM is found sensitive to Citation: Dimitriadou, S.; wind speed and depicts interactions among climate parameters (T, evaporative demand and water Nikolakopoulos, K.G. Reference availability) in the frame of climate change. The years 2016–2019 are four of the warmest since the Evapotranspiration (ETo) Methods preindustrial era. Hargreaves–Samani’s estimations for the Decembers of 2016–2019 were almost Implemented as ArcMap Models with identical to MODIS ET, despite their different physical meaning. However, for the Augusts there are Remote-Sensed and Ground-Based considerable discrepancies between the methods’ and MODIS’s estimates, attributed to the higher Inputs, Examined along with MODIS evaporative demand in the summertime.