Pan evaporation and potential evapotranspiration

Abstract The performance of potential evapotranspiration (PET) methods such as pan evaporation (physical measurement), empirical formulas (Penman–Monteith (PM), Hargreaves and Thornthwaite) and satellite-derived PET (MOD16) were assessed in a semiarid region of central India. The satellite-based PET was obtained from Moderate Resolution Imaging Spectroradiometer (MODIS). The comparisons between different methods were made with observed pan evaporation (ETpan) data to identify the best method for the semiarid region. Further, the future projection of PET was carried out using RCP4.5 emission scenario of seven CMIP5 models. Two approaches were applied for the projection of PET. In the first approach, RCP4.5 scenario data are directly used in the PM method, and in the second approach, these variables are used as a predictor in the calibrated and validated least square support vector machine (LS-SVM) model. The projection of PET was made using the best-identified model among PM and LS-SVM from the years 2006–2100. The results show that MOD16 and Hargreaves overestimate the PET; however, PM and Thornwaite underestimate the PET. PM based PET is closely related with ETpan and is a good indicator of ETpan in a semiarid region. GFDL-ESM2M is identified as the most skillful CMIP5 model, and results show that PET is projected to increase in future using the LS-SVM model.

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CONVERSION OF LATENT EVAPORATION TO POTENTIAL EVAPOTRANSPIRATION

Canadian Journal of Plant Science ◽

10.4141/cjps58-028 ◽

1958 ◽

Vol 38 (2) ◽

pp. 164-172 ◽

Cited By ~ 21

Author(s):

R. M. Holmes ◽

G. W. Robertson

Keyword(s):

Conversion Factor ◽

Potential Evapotranspiration ◽

Porous Ceramic ◽

Ceramic Plate ◽

Pan Evaporation ◽

Block Methods ◽

Glazed Ceramic ◽

Scheduling Irrigation ◽

Field Plots ◽

Porous Ceramic Plate

Potential evapotranspirometers and various evaporation pans are commonly used to estimate potential evapotranspiration. These instruments are expensive, large, difficult to install and use. A black Bellani plate atmometer is suggested as a simple instrument to replace these large tanks. It consists of a black, porous, ceramic plate, mounted on a glazed ceramic cup. The plate surface is kept moist by the water held in the cup. Evaporation from this surface is a measure of the drying ability of the air and is called "latent evaporation". Comparisons of various evaporimeters have shown the Bellani atmometer to be accurate and responsive to meteorological variables.Latent evaporation was compared with open-pan evaporation (from a 4-foot diameter buried tank) at several sites across Canada. Latent evaporation was also compared with evapotranspiration from irrigated field plots and evapotranspirometer tanks. The conversion factor of 0.0034 inches of evapotranspiration from irrigated fields, and 0.0032 inches of open-pan evaporation for each cubic centimetre of latent evaporation has been tentatively established. Latent evaporation and moisture block methods have shown excellent agreement in scheduling irrigation.

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Spatial Interpolation of Daily Potential Evapotranspiration for New Zealand Using a Spline Model

Journal of Hydrometeorology ◽

10.1175/jhm572.1 ◽

2007 ◽

Vol 8 (3) ◽

pp. 430-438 ◽

Cited By ~ 43

Author(s):

Andrew Tait ◽

Ross Woods

Keyword(s):

New Zealand ◽

Spatial Interpolation ◽

Input Data ◽

Potential Evapotranspiration ◽

High Elevation ◽

Irrigation Scheduling ◽

Smoothing Spline ◽

Mean Square ◽

Pan Evaporation ◽

Streamflow Modeling

Abstract Potential evapotranspiration (PET) is an important component of water balance calculations, and these calculations form an equally important role in applications such as irrigation scheduling, pasture productivity forecasts, and groundwater recharge and streamflow modeling. This paper describes a method of interpolating daily PET data calculated at climate stations throughout New Zealand onto a regular 0.05° latitude–longitude grid using a thin-plate smoothing spline model. Maximum use is made of observational data by combining both Penman and Priestley–Taylor PET calculations and raised pan evaporation measurements. An analysis of the interpolation error using 20 validation sites shows that the average root-mean-square error varies between about 1 mm in the summer months to about 0.4 mm in winter. It is advised that interpolated data for areas above 500-m elevation should be used with caution, however, due to the paucity of input data from high-elevation sites.

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THE CONTRIBUTION OF CLIMATIC FACTORS ON MICROLYSIMETRIC POTENTIAL EVAPOTRANSPIRATION (PET)AND PAN EVAPORATION AT SAMARU, NIGERIA

Nigerian Journal of Soil and Environmental Research ◽

10.4314/njser.v4i1.28376 ◽

2004 ◽

Vol 4 (1) ◽

Author(s):

RN Edoga

Keyword(s):

Climatic Factors ◽

Potential Evapotranspiration ◽

Pan Evaporation

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CLASS A PAN EVAPORATION VERSUS POTENTIAL EVAPOTRANSPIRATION AT SEVEN LOCATIONS IN PUERTO RICO

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v74i3.6673 ◽

1969 ◽

Vol 74 (3) ◽

pp. 343-346

Author(s):

Carmela Chao de Báez ◽

Megh R. Goyal

Keyword(s):

Puerto Rico ◽

Potential Evapotranspiration ◽

Pan Evaporation ◽

Class A ◽

Class A Pan

CLASS A PAN EVAPORATION VERSUS POTENTIAL EVAPOTRANSPIRATION AT SEVEN LOCATIONS IN PUERTO RICO

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A Method of Calculating Potential Evapotranspiration from Pan Evaporation Data

Journal of Agricultural Meteorology ◽

10.2480/agrmet.13.81 ◽

1958 ◽

Vol 13 (3) ◽

pp. 81-85

Author(s):

S. SUZUKI ◽

H. FUKUDA

Keyword(s):

Potential Evapotranspiration ◽

Pan Evaporation

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Comparative evaluation of different reference evapotranspiration models

Journal of Applied and Natural Science ◽

10.31018/jans.v9i1.1239 ◽

2017 ◽

Vol 9 (1) ◽

pp. 609-613

Author(s):

C. K. Arya ◽

R. C. Purohit ◽

L. K. Dashora ◽

P. K. Singh ◽

Mahesh Kothari ◽

...

Keyword(s):

Water Resource Management ◽

Meteorological Parameters ◽

Reference Evapotranspiration ◽

Potential Evapotranspiration ◽

Accurate Estimation ◽

Climatic Data ◽

Pan Evaporation ◽

Alternative Method ◽

Monteith Equation

The study was carried out to select best alternative method for the estimation of reference evapotranspi-ration (ET0). Accurate estimation of potential evapotranspiration is a necessary step in water resource management. Recently, the FAO-56 version of Penman-Monteith equation has been established as a standard for calculating ref-erence evapotranspiration (ET0) which requires measurement of a number of meteorological parameters namely, air temperature, relative humidity, solar radiation, and wind speed which may not be available in most of the meteoro-logical stations. Still there are different approaches (requiring less data) which estimate ET0 closely to Penman- Monteith (P-M) method for different climatological conditions. The present study is based on analysis of long term of 13 years (2000 to 2012) climatic data to calculate monthly reference evapotranspiration for Capsicum production (September–March) and also to compare the performance of evapotranspiration equations for Jhalawar district of Rajasthan with the standard FAO-56 Penman-Monteith method on the basis of the least root mean square error (RMSE) analysis. Hargreaves method and Pan evaporation (E-Pan) method overestimated the values of ETo when compared with FAO-56 Penman-Monteith method. On the basis of lowest value of RMSE, Pan evaporation method is found best alternative method to FAO-56 Penman-Monteith method in the study area.

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