I have utilized several Energy Balance algorithms (e.g. SEBAL, METRIC, SSEB... etc) to calculate the actual evapotranspiration (ETa) using satellite images since Remote sensing data, which are the inputs for the models, capture the ACTUAL condition (i.e. NDVI, Land Surface Temperature ... etc). I find many papers that these models can calculate the potential evapotranspiration (ETp) as well but HOW? which inputs I have to modify to get the ETp not the ETa?
Thanks Dr. Anoop for sharing these papers. I will have a look and let you know if I get the answer.
Dear Dr. Anoop, thanks for sharing the selected publications. I had a look and found that there is still limitation f applying the available methods.
For example, Holterman (2015) mentioned that ETp= ETa + ETdef and did not mention how the ETdef was calculated. The author used a model from eLEAF (ET tool). Lang et al. (2017) assumed the ETp is the grass reference ET (ETo) and applied eight methods with FAO Penman–Monteith method in Southwestern China. However, the authors used the remote sensing inputs (e.g. NDVI) of the actual condition, which might not reflect the potential one. I found that the method utilized by Tsouni et al. (2008) is much better. However, Tsouni et al. (2008) used the crop coefficient Kc which was estimated on a daily basis for the entire study period according to the single crop coefficient method and a series of assumptions for the crops of the study area.
Thanks again and I still looking for an answer regard to how to get ETp from remote sensing despite of using actual conditions data?
I think you should use FAO 56 applied to remote sensing data. We applied the Hargreaves-Samani method recommended by FAO 56 to calculate successful evapotranspiration reference. It is much simpler than using SEBS models, which I think should be used for crop irrigation.
Luis Morales-Salinas, Samuel Ortega-Farías, Camilo Riveros-Burgos, José Neira-Román, Marcos Carrasco-Benavides & Rafael López-Olivari (2017) Monthly calibration of Hargreaves–Samani equation using remote sensing and topoclimatology in central-southern Chile, International Journal of Remote Sensing, 38:24,7497-7513, DOI: 10.1080/01431161.2017.1323287
I recommend the use of the METRIC model. It is easy to apply if you use the WATER library of R (CRAN). I have had good results applying this model in fruit orchards in Chile.
https://cran.r-project.org/web/packages/water/index.html
https://cran.r-project.org/web/packages/water/vignettes/METRIC_advanced.html
https://cran.r-project.org/web/packages/water/vignettes/Landsat8.html
Thanks Dr. Luis for your kind feedback. Indeed it is useful. I will read more on how to calculate ETo from the suggested topic and will write to you.
Dear Islam Sabry Al Zayed
If you need help, I will gladly provide it. My email is [email protected].
Best regards
LM
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