hi rakesh,

maybe the following papers are of interest for you:

- R. E. Yoder, L. O. Odhiambo, W. C. Wright, 2005: EVALUATION OF METHODS FOR ESTIMATING DAILY REFERENCE CROP EVAPOTRANSPIRATION AT A SITE IN THE HUMID SOUTHEAST UNITED STATES, Applied Engineering in Agriculture, Vol. 21, No. 2. (2005), pp. 197-202

- IRMAK, S., T.A. HOWELL, R.G. ALLEN, J.0. PAYERO and D.L. MARTIN, 2005: Standardized ASCE Penman-Monteith: Impact of sum-of-hourly vs. 24-hour timestep

computations at reference weather station sites. Transactions of the ASAE. 48(3): 1063-1077.

- Fank, J., 2007: Comparison of calculated ET0 to measured ET using precision lysimeters. http://www.lysimeter.com/Wagna/Poster_Abstract_EGU_Fank.pdf

Fank also published some papers in german regarding the timesteps of ETo-PM.

good luck, maybe you can post some results when the time has come,

cheers, christian

http://www.lysimeter.com/Wagna/Poster_Abstract_EGU_Fank.pdf

Dear Christian,

Thanks a lot. I have already collected a bundle of papers. But many of the papers, references you suggested are new, I am sure it will help me.

Of course result will be shared, but as anyone can guess, reading these papers and analyzing will take a long time.

Regards

Totally clear, i am also into it at the moment. If similar papers cross my way during literature research i will let you know.

Glad to help you.

I am working on forest PET. Seems many exciting PET models have problems to estimate forest PET.

All see papers

Rao, L., G. Sun, C.R. Ford, and J. Vose. 2011. Modeling potential evapotranspiration of two forested watersheds in the Southern Appalachians, USA. Transactions of the ASABE. Vol. 54(6): 2067-2078.

Lu, J., G. Sun, D.M. Amatya, S.G. McNulty. 2005. A Comparison of Six Potential Evapotranspiration Methods for Regional Use in the Southeastern United States. Journal of American Water Resources Association, 41:621-633.

Thanks. I am using the second paper as my basic reference paper to build up my further analysis.

You can use one of the most common ways to estimate the PET , witch i i believe is with the use of CROPWAT8 witch uses the Penman-Monteith method and also on its help menu has a lot of documentation and probubly you ll find some links to papers from FAO within this documentation , and you could compare the two methods cropwat8 uses to estimate PET. The second one is a very simple method that estimates PET with only the use of min and max daily temperatures and the latitude of an area witch i ve seen it overestimates PET or downestimates it depending on warm or hot-dry periods.. In my thesis i used this PET for the region of ARTA GREECE to estimate the PET and the estimated the RealET with the use of Hydrological model MikeShe and corine land cover with some correction as it matter on rocks outcrops using google earth and slopes.Papers i have are mostly in Greek .. sorry.

very valuable suggestion. Yes, I am taking PM method value as the base reference value (as i am fully depending on seconday data). Sorry to hear that your papers are in Greek, which is 'greek' to me. If you have any in English please share.

Thanks for the vote up , I will have my paper in English in two months witch i think is a lot.. but i might find other papers in English .

The Hamon;s method that uses air temp and daylength as the two input variables is most poplar method to estimate PET.

The challenge of comparisons of different PET/ref ET methods is that we are lack of a reference dataset to do this. Existing PET/ref ET can be categorized into three types: (1) temperature based methods, (2) temperature and radiation based methods, and (3) methods considering all the controlling factors, such as temperature, radiation, wind speed, and water vapor deficit. Available input data limit the application of the methods. Furthermore, most of the methods include empirical parameters, resulting in a requirement for local calibration. Something else needs to keep in mind when selecting the methods is the time scale for your application. If one want to use it at daily or monthly scales (i.e., seasonal variation), most methods have comparable accuracy. However, if one want to check variability at time scales longer than annual, a method considering more parameters maybe better.

Thanks for your inputs

hi Jean vidal,

Thanks for sharing a potential source.

Dear Jean Vidal,

I could complete your paper just now only. Excellent paper. I was aiming to compile different methods for PET estimation, but dont feel the need anymore. Your work is an excellent guide for that purpose.

Hi, an interesting comparison of 27 existing methods for PET estimation and their influence on 4 hydrological models efficiencies: Oudin et al (2005) Which potential evapotranspiration input for a lumped rainfall-runoff model?Part 2 – Towards a simple and efficient potential evapotranspiration model for rainfall-runoff modelling. J Hydrol 303: 290-306. doi: 10.1016/j.jhydrol.2004.08.026

ٌWhen your only available data is daily temperature (mean daily temperature) the best method would be Thornthwaite. but you must concern that this method is only good for wet regions and it underestimates this component up to 39 percent in dry regions (see https://www.researchgate.net/publication/222499511_The_ARNO_rainfallrunoff_model) you must concern that the best method is PM which needs lots of meteorological data (see www.kimberly.uidaho.edu/ref-et/fao56.pdf‎ ) but in lack of data it cant be used. A good way to resolve this problem is to modify Thornthwaite or other ET methods by using the PM method in a specific place which we have the required information. (see www.ejournal.unam.mx/atm/Vol22-4/ATM002200401.pdf‎)

Article The ARNO rainfall—runoff model

Hi Rakesh,

Try FAO-56 for a variety of methods:

http://www.fao.org/docrep/X0490E/X0490E00.htm

If its India you;re interested in, my dissertation results for 2 estimates (Hargreaves and Priestley-Taylor) should still be available via the India Water Portal at district level.

Vishal, nice to hear from you after a long time. I was looking for compiling all the available methods, but yes, more concentrated with India data.

Please refer to

1. LeeT.S., Najim M.M.M., Aminul M.H., H.Y. Feng, 2005. Modeling of Changes in Evapotranspiration for an Area in Peninsular Malaysia, Pertanika Journal of Science and Technology. 01/2005; 13(2):237-248. (you can download from Researchgate)

2. T S Lee, M M M Najim, M H Aminul, 2004. Estimating evapotranspiration of irrigated rice at the West coast of the Peninsular of Malaysia Journal of Applied Irrigation Science. 01/2004; 39(1):103-117. (you can download from Researchgate)