Meteorological Influences on Reference Evapotranspiration in Different Geographical Regions

Abstract

It is critical to understand how meteorological variables impact reference evapotranspiration (ETo) since meteorological variables have a different effect on ETo. This study examined the impact of meteorological variables on ETo on the Korean Peninsula under complex climatic and geographic conditions in order to understand how ETo and meteorological variables have changed over the past 42 years. Different geographical conditions were analyzed, including plains, mountains, and coastal areas on a seasonal and annual basis. ETo was estimated using the Penman-Monteith method by the Food and Agriculture Organization (FAO) using daily relative humidity (RH), solar radiation (Rs), maximum temperature (Tmax), minimum temperature (Tmin), and wind speed (Ws). According to the results, the maximum mean seasonal and annual ETo occurred on the southern coast, while the minimum occurred in the mountainous area and along the east coast. Seasonal ETo is highest in summer, and is lowest in winter for all regions. The investigation of meteorological variables on ETo revealed that the response varied by area, and the magnitudes of sensitivity varied by location and season. RH is the most critical meteorological variable to affect ETo in all seasons, except summer, when Tmin is the most sensitive parameter. The results revealed that different regions showed different responses to the change in ETo by changing the meteorological variables. Meteorological variables affecting ETo differ with different geologic conditions and seasons. in mountainous areas revealed almost similar responses to the change in RH, Rs, and Tmax (±10% change in ETo) during the spring season. However, for other regions, RH and Tmax caused changes to ETo throughout, ranging from −15% to +20% in the plain area, −20% to +15% in the west and east coast, and −20% to +10% in the south coast. In addition, there were significant differences in parameter responses between regions and seasons, which was confirmed by the results.