نتایج جستجو برای: modified penman

تعداد نتایج: 251477  

2017
Lameck O. Odhiambo R. E. Yoder D. C. Yoder L. O. Odhiambo

Daily evapotranspiration (ET) rates are needed for irrigation scheduling. Owing to the difficulty of obtaining accurate field measurements, ET rates are commonly estimated from weather parameters. A few empirical or semi–empirical methods have been developed for assessing daily reference crop ET, which is converted to actual crop ET using crop coefficients. The FAO Penman–Monteith method, which...

Journal: :Remote Sensing 2015
Fei Feng Jiquan Chen Xianglan Li Yunjun Yao Shunlin Liang Meng Liu Nannan Zhang Yang Guo Jian Yu Minmin Sun

Accurate estimation of latent heat flux (LE) is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using...

2014
Yunjun Yao Shunlin Liang Xianglan Li Yang Hong Joshua B. Fisher Nannan Zhang Jiquan Chen Jie Cheng Shaohua Zhao Xiaotong Zhang Bo Jiang Liang Sun Kun Jia Kaicun Wang Yang Chen Qiaozhen Mu Fei Feng

Accurate estimation of the satellite-based global terrestrial latent heat flux (LE) at high spatial and temporal scales remains a major challenge. In this study, we introduce a Bayesian model averaging (BMA) method to improve satellite-based global terrestrial LE estimation by merging five process-based algorithms. These are the Moderate Resolution Imaging Spectroradiometer (MODIS) LE product a...

2004
Raj Vir Singh

Wheat is an important crop of India. Precise estimates of evapotranspiration can be obtained by multiplying crop coefficients to reference evapotranspiration using readily available climatic data. PenmanMonteith equation is adopted world wide as the most reliable and accurate method for computing reference evapotranspiration. The Food and Agriculture Organization (FAO) presented crop coefficien...

Journal: :British Journal of Ophthalmology 1983

Journal: :آب و خاک 0
موسوی بایگی موسوی بایگی عرفانیان عرفانیان سرمد سرمد

abstract one of the losses decrease's ways in fields, is the proper irrigation management, which its base is the accurate estimation of crop water requirement. equations which are used to calculate the reference evapotranspiration (eto), do not use the same climatic parameters and due to their empirical base, are not match to all climatic situations. so it is needed to clarify proper methods fo...

2008
M. Weiß L. Menzel

This study compares four different potential evapotranspiration equations according to Priestley Taylor, Kimberly Penman, Penman Monteith (FAO-56) and Hargreaves on a global basis to demonstrate their difference, and assess their impact on the calculation of stream flows. The various equations of potential evapotranspiration show great differences in magnitude. But due to the limited availabili...

1997
C. A. Federer B. Fekete

Five methods (Thornthwaite, Hamon, Jensen-Haise, Turc, and Penman) for estimating potential evaporation for a reference surface (PEr) were compared to four methods (Priestley-Taylor, McNaughton-Black, Penman-Monteith, and ShuttleworthWallace) for estimating surface-dependent potential evaporation (PEs) using three cover types at each of seven locations from Fairbanks, Alaska, to San Juan, Puert...

شاهرخ زندپارسا, , علیرضا سپاسخواه, , ابوالفضل مجنونی هریس, , علی اکبر کامگار حقیقی, ,

Optimal crop water requirement is needed for precise irrigation scheduling. Prediction of crop water requirements is a basic factor to achieve this goal. In this study, maize potential evapotranspiration (ETp) was prediced by maize simulation model (MSM). Then, it was evaluated and validated using experimental field data obtained in Agricultural Research Station of Shiraz University (Bajghah, F...

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