Environmental Sciences Proceedings (Mar 2023)

Estimating the Potential Evapotranspiration of Egypt Using a Regional Climate Model and a High-Resolution Reanalysis Dataset

  • Samy Ashraf Anwar,
  • Irida Lazić

DOI
https://doi.org/10.3390/ECWS-7-14253
Journal volume & issue
Vol. 25, no. 1
p. 29

Abstract

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Station observation is a good data source to monitor the potential evapotranspiration (PET) changes of a specific site particularly for the purpose of crop irrigation activities; however it represents only the site geographic characteristics and provides real-time/historical records. Hence, there was an urgent need to find a promising tool and a simple empirical to predict/project the PET in locations where station observation is not feasible. The Hargreaves–Samani method (HS) is recommended after the Penman−Monteith equation. To address this issue, the Regional Climate Modeling version 4 (RegCM4) with spatial resolution 25 km was used to compute the PET using the HS for the period 1979–2017. Era-Interim reanalysis of 1.5 degrees (EIN15) and NCEP/NCAR reanalysis version 2 of 2.5 degrees (NNRP2) were used to examine the influence of the lateral boundary condition on the simulated PET. The two simulations were designated as EIN15-RegCM4 and NNRP2-RegCM4, respectively. To examine the possible influences on the simulated PET, a comparison was conducted between EIN15-RegCM4 and NNRP2-RegCM4. After that, a comparison was conducted between the original HS formula (HS) and its calibrated version (HSnew) with respect to the 0.1−degree ERA5-land derived reanalysis product (hereafter ERA5) using EIN15-RegCM4 (as an example). Results showed that switching between EIN15 and NNRP2 did not show a notable influence on the simulated PET. Further, calibrating the HS coefficients indicates a considerable improvement in estimating the PET (relative to the original equation) when it is compared with ERA5. Such improvement is confirmed by a significant low mean bias. Over the majority of locations, the RegCM4 shows a good performance using the calibrated HS equation. In conclusion, the RegCM4 can be used to estimate the PET using the calibrated HS either for making a daily forecast or for projecting the future PET under different global warming scenarios.

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