scholarly journals Assessing suitability of temperature-based reference evapotranspiration methods for semi-arid basin of Maharashtra

2021 ◽  
Vol 21 (3) ◽  
pp. 351-356
Author(s):  
P.S. WABLE ◽  
M.K. JHA ◽  
S.D. GORANTIWAR
Keyword(s):  
Climatic Condition ◽  
Arid Regions ◽  
Reference Evapotranspiration ◽  
Monsoon Season ◽  
Meteorological Data ◽  
Temperature Data ◽  
Western India ◽  
Climatic Data ◽  
Suitable Temperature ◽  
Semi Arid

FAO Penman-Monteith (FAO-PM) is deemed as a sole standard method for estimating reference evapotranspiration (ET ). However, limited availability of meteorological data at spatial and temporal o scales restricts the application of this method. To address this issue, the FAO 56 experts suggested three methods when only maximum and minimum temperature data are available: (i) Temperature-based Penman-Monteith (PMT-1) method wherein T ≈ T (ii) PMT-2 wherein T ≈ T -2.5, and (iii) dew min dew min Hargreaves method. These ET methods were assessed for a semi-arid basin of Western India which lacks adequate climatic data. The performances of the ET methods were evaluated against the standard FAO-PM method using salient statistical and graphical indicators, together with the sensitivity analysis. The results of the three temperature-based methods had a tendency of over-predication of ET in the study area. The PMT-1 method, however, provided superior ET estimates compared to PMT-2 and Hargreaves methods. For estimating monthly ET , the FAO-PM method was most sensitive to temperature. Further, ET of the monsoon season over the study area increased from 5 to 12% during 'drought' years compared to 'normal' years. It was concluded that PMT-1 method is the most suitable temperature-based method for estimating ET in semi-arid regions under limited climatic condition.

Spatial distribution and temporal variation of reference evapotranspiration in arid and semi-arid regions of Iran

2011 ◽  
Vol 26 (4) ◽  
pp. 500-512 ◽  
Author(s):  
Hossein Tabari ◽  
Ali Aeini ◽  
P. Hosseinzadeh Talaee ◽  
B. Shifteh Some'e
Keyword(s):  
Spatial Distribution ◽  
Temporal Variation ◽  
Arid Regions ◽  
Reference Evapotranspiration ◽  
Semi Arid

scholarly journals COMPARAÇÃO ENTRE MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA O MUNICÍPIO DE PETROLINA, PE

Irriga ◽  
2017 ◽  
Vol 1 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Roberta Daniela Silva Santos ◽  
Marcello Henryque Costa de Souza ◽  
Regiane De Carvalho Bispo ◽  
Kevim Muniz Ventura ◽  
Luis Henrique Bassoi
Keyword(s):  
Reference Evapotranspiration ◽  
Estimation Method ◽  
Arid Climate ◽  
Estimation Methods ◽  
Coefficient Of Determination ◽  
Climatic Data ◽  
Test Field ◽  
Rating Method ◽  
And Performance ◽  
Semi Arid

COMPARAÇÃO ENTRE MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA PARA O MUNICÍPIO DE PETROLINA, PE  ROBERTA DANIELA DA SILVA SANTOS1; MARCELLO HENRYQUE COSTA DE SOUZA1; REGIANE DE CARVALHO BISPO1; KEVIM MUNIZ VENTURA1 E LUÍS HENRIQUE BASSOI2 1Programa de Pós-Graduação em Irrigação e Drenagem, Universidade Estadual Paulista “Júlio de Mesquita Filho”- UNESP/FCA, Rua Dr. José Barbosa de Barros, 1780, Botucatu, SP, [email protected], [email protected], [email protected], [email protected] Embrapa Instrumentação, São Carlos, SP, [email protected]  1 RESUMO O conhecimento da evapotranspiração é vital na determinação das necessidades hídricas de uma cultura. Diante disso, o objetivo deste trabalho foi comparar o desempenho de sete métodos de estimativa da evapotranspiração de referência em relação ao método de Penman-Monteith, adotado como padrão, para o município de Petrolina, PE. Foram utilizados dados climáticos diários de 2004 a 2015, para estimar da ET0, obtidos na estação meteorológica automática do Campo Experimental de Bebedouro da Embrapa Semiárido, Petrolina, PE. Os indicadores estatísticos utilizados na avaliação foram: coeficiente de determinação (r²); coeficiente de correlação (r); índice de concordância (d) e índice de desempenho (c). Os valores do r² mostraram que o método de estimativa que melhor se ajustou ao método de Penman-Monteith foi o de Ivanov (0,73); seguido pelos métodos de Jensen-Haise (0,64); Makkink e Priestley-Taylor (0,63); Villa Nova (0,62); Hargreaves e Samani (0,53) e Hamon (0,45). No entanto, com relação ao do índice “c”, Hamon foi classificado com “péssimo”; Makkink como “mau”; Hargreaves e Samani e Villa Nova como “sofrível”; Ivanov e Priestley-Taylor como “mediano”; e Jensen-Haise como “bom”. Esse último método foi considerado como o de melhor classificação de desempenho. Palavras-chave: Penman-Monteith, correlação, semiárido.  SANTOS, R. D. S.; SOUZA, M. H. C.; BISPO, R. de C.; VENTURA, K. M.; BASSOI, L. H.METHOD-COMPARISON STUDY TO ESTIMATE THE REFERENCE EVAPOTRANSPIRATION IN PETROLINA, PE  2 ABSTRACT The knowledge on evapotranspiration is vital in determining the water requirements of a crop. Therefore, this paper aims to compare the performance of seven of estimation methods for the reference evapotranspiration in relation to the Penman-Monteith method, adopted as standard, for the municipality of Petrolina, state of Pernambuco, Brazil. We used daily climatic data from 2004 to 2015 to estimate the ET0 coefficient, obtained in the automatic weather station of the Test Field in Bebedouro, Embrapa in the Semi-arid climate. The statistical indicators used in the evaluation were: coefficient of determination (r²), correlation coefficient (r), agreement index (d) and performance index (c). The r2 values showed that the estimation method that best fitted to the Penman-Monteith method was Ivanov's (0.73), followed by Jensen-Haise (0.64), Makkink and Priestley-Taylor (0.63), Villa Nova (0.62), Hargreaves and Samani (0.53) and Hamon (0.45) methods. However, in relation to the index "c", Hamon was classified as "very poor"; Makkink as "poor"; Hargreaves and Samani and Villa Nova as "tolerable"; Ivanov and Priestley-Taylor as "medium"; and Jensen-Haise as "good". The last one was considered as the best performance rating method. Keywords: Penman-Monteith, correlation, semi-arid climate.

scholarly journals Global comparison of 20 reference evapotranspiration equations in a semi-arid region of Iran

2018 ◽  
Vol 50 (1) ◽  
pp. 282-300 ◽  
Author(s):  
Hadi Farzanpour ◽  
Jalal Shiri ◽  
Ali Ashraf Sadraddini ◽  
Slavisa Trajkovic
Keyword(s):  
Arid Region ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Irrigation Scheduling ◽  
Climatic Conditions ◽  
Accurate Estimation ◽  
Management Scenarios ◽  
Global Comparison ◽  
Semi Arid Region ◽  
Semi Arid

Abstract Accurate estimation of reference evapotranspiration (ETo) is a major task in hydrology, water resources management, irrigation scheduling and determining crop water requirement. There are many empirical equations suggested by numerous references in literature for calculating ETo using meteorological data. Some such equations have been developed for specific climatic conditions while some have been applied universally. The potential for usage of these equations depends on the availability of necessary meteorological parameters for calculating ETo in different climate conditions. The focus of the present study was a global cross-comparison of 20 ETo estimation equations using daily meteorological records of 10 weather stations (covering a period of 12 years) in a semi-arid region of Iran. Two data management scenarios, namely local and cross-station scenarios, were adopted for calibrating the applied equations against the standard FAO56-PM model. The obtained results revealed that the cross-station calibration might be a good alternative for local calibration of the ETo models when proper similar stations are used for feeding the calibration matrix.

scholarly journals Improving Estimation of Gross Primary Production in Dryland Ecosystems by a Model-Data Fusion Approach

2019 ◽  
Vol 11 (3) ◽  
pp. 225 ◽  
Author(s):  
Haibo Wang ◽  
Xin Li ◽  
Mingguo Ma ◽  
Liying Geng
Keyword(s):  
Carbon Cycle ◽  
Arid Region ◽  
Arid Regions ◽  
Meteorological Data ◽  
Gross Primary Production ◽  
Arid Ecosystems ◽  
Desert Ecosystems ◽  
Dryland Ecosystems ◽  
Semi Arid

Accurate and continuous monitoring of the production of arid ecosystems is of great importance for global and regional carbon cycle estimation. However, the magnitude of carbon sequestration in arid regions and its contribution to the global carbon cycle is poorly understood due to the worldwide paucity of measurements of carbon exchange in arid ecosystems. The Moderate Resolution Imaging Spectroradiometer (MODIS) gross primary productivity (GPP) product provides worldwide high-frequency monitoring of terrestrial GPP. While there have been a large number of studies to validate the MODIS GPP product with ground-based measurements over a range of biome types. Few studies have comprehensively validated the performance of MODIS estimates in arid and semi-arid ecosystems, especially for the newly released Collection 6 GPP products, whose resolution have been improved from 1000 m to 500 m. Thus, this study examined the performance of MODIS-derived GPP by compared with eddy covariance (EC)-observed GPP at different timescales for the main ecosystems in arid and semi-arid regions of China. Meanwhile, we also improved the estimation of MODIS GPP by using in situ meteorological forcing data and optimization of biome-specific parameters with the Bayesian approach. Our results revealed that the current MOD17A2H GPP algorithm could, on the whole, capture the broad trends of GPP at eight-day time scales for the most investigated sites. However, GPP was underestimated in some ecosystems in the arid region, especially for the irrigated cropland and forest ecosystems (with R2 = 0.80, RMSE = 2.66 gC/m2/day and R2 = 0.53, RMSE = 2.12 gC/m2/day, respectively). At the eight-day time scale, the slope of the original MOD17A2H GPP relative to the EC-based GPP was only 0.49, which showed significant underestimation compared with tower-based GPP. However, after using in situ meteorological data to optimize the biome-based parameters of MODIS GPP algorithm, the model could explain 91% of the EC-observed GPP of the sites. Our study revealed that the current MODIS GPP model works well after improving the maximum light-use efficiency (εmax or LUEmax), as well as the temperature and water-constrained parameters of the main ecosystems in the arid region. Nevertheless, there are still large uncertainties surrounding GPP modelling in dryland ecosystems, especially for desert ecosystems. Further improvements in GPP simulation in dryland ecosystems are needed in future studies, for example, improvements of remote sensing products and the GPP estimation algorithm, implementation of data-driven methods, or physiology models.

Analysis of trends in temperature data in arid and semi-arid regions of Iran

2011 ◽  
Vol 79 (1-2) ◽  
pp. 1-10 ◽  
Author(s):  
Hossein Tabari ◽  
P. Hosseinzadeh Talaee
Keyword(s):  
Arid Regions ◽  
Temperature Data ◽  
Semi Arid

scholarly journals Spatial variability of annual and monthly Potential Evapotranspiration (PET) over India

MAUSAM ◽  
2021 ◽  
Vol 63 (4) ◽  
pp. 581-586
Author(s):  
I. J. VERMA ◽  
V.K. SONI ◽  
N.D. SABALE ◽  
A.L. KOPPAR
Keyword(s):  
Potential Evapotranspiration ◽  
Monsoon Season ◽  
Meteorological Data ◽  
Central India ◽  
Western India ◽  
Desert Area ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
The Mean ◽  
Monteith Equation

In this study, meteorological data for well distributed 140 locations in India for the period (1971-2005) have been utilized for estimation of potential evapotranspiration (PET) by Penman-Monteith equation. The highest average annual PET of 2342 mm was at Jalgaon and lowest of 921 mm at Ging. Range of average annual PET is 1421 mm. The mean annual PET averaged for all stations over India is 1547 mm with 12% contribution in winter, 34% in pre-monsoon, 35% in monsoon and 19% in post-monsoon seasons. The lowest centers with annual PET less than 1400 mm are mainly located above 30 degree N latitude. The high centers with annual PET more than 1800 mm are located in desert area and central India, with lowest values at hill stations during most of the months. The higher monthly PET values in excess of 200 mm are normally observed during pre-monsoon and monsoon over western and Central India. As the monsoon advances, the PET values over western India decrease gradually. The lower PET values are observed during winter and post-monsoon season. The lowest mean monthly PET of 82.1 mm is in December and highest mean monthly PET of 199.6 mm is in May. Mean annual and monthly PET over (2° × 2°) latitude/longitude grids have been developed and presented.

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