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ARS Home » Plains Area » El Reno, Oklahoma » Grazinglands Research Laboratory » Forage and Livestock Production Research » Research » Publications at this Location » Publication #367068

Research Project: Integrated Agroecosystem Research to Enhance Forage and Food Production in the Southern Great Plains

Location: Forage and Livestock Production Research

Title: Sensitivity of reference evapotranspiration to weather variables across seven regions of Turkey

Author
item YILDIRIM, TUGBA - Ege University
item Wagle, Pradeep
item Gowda, Prasanna
item MENGU, GULAY - Ege University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2021
Publication Date: 5/7/2021
Citation: Yildirim, T., Wagle, P., Gowda, P.H., Mengu, G. 2021. Sensitivity of reference evapotranspiration to weather variables across seven regions of Turkey. Agrosystems, Geosciences & Environment. 4(2):e20155. https://doi.org/10.1002/agg2.20155.
DOI: https://doi.org/10.1002/agg2.20155

Interpretive Summary: Evapotranspiration (ET), a key component of the hydrological cycle, is important for an assessment of water resources, drought, and irrigation management. Therefore, it is crucial to accurately determine ET. Daily weather data from 1984 to 2018 from seven weather stations representing seven climatic regions in Turkey were used to estimate reference ET (ET rate from a reference surface which is not short of water). Sensitivity analysis of input weather variables (air temperature, wind speed, and solar radiation) was also performed to determine the relative effects of measurement errors on the accuracy of reference ET across seven climatic regions in Turkey. Comparison of the sensitivity coefficients indicated that reference ET was the most sensitive to wind speed followed by air temperature across Turkey. However, responses of reference ET to changes in weather parameters varied across the regions. For example, Marmara Region had the largest impact of errors in air temperature but the smallest impact of errors in wind speed on the calculated reference ET. Similarly, the Southeastern Anatolia and Mediterranean Regions had greatest impact of errors in wind speed but smallest impact of errors in air temperature on the calculated reference ET. Our sensitivity analysis suggests that weather stations located in different regions of Turkey require different maintenance protocols and sensor accuracies.

Technical Abstract: Evapotranspiration (ET) is a key component of the hydrological cycle which is important for an assessment of water resources, drought, and irrigation management. Therefore, it is crucial to accurately determine ET. Daily weather data from 1984 to 2018 from seven weather stations representing seven climatic regions in Turkey were used to estimate reference ET (ETref). A sensitivity analysis of input weather variables (air temperature, wind speed, and solar radiation) was conducted to determine the relative effects of measurement errors on the accuracy of calculated grass (ETos) and alfalfa (ETrs) reference ET across different climatic regions in Turkey. Comparison of the sensitivity coefficients indicated that ETref was most sensitive to wind speed followed by air temperature across Turkey. However, responses of ETos and ETrs to changes in weather parameters varied across the regions. The Marmara Region had the largest impact of errors in air temperature but the smallest impact of errors in wind speed on the calculated ETref. Likewise, the Southeastern Anatolia and Mediterranean Regions had greatest impact of errors in wind speed but smallest impact of errors in air temperature on the calculated ETref. These results suggest that different maintenance protocols and sensor accuracies are needed for weather stations in different regions of Turkey.