scholarly journals Modification of FAO Penman–Monteith equation for minor components of energy

2018 ◽  
Vol 50 (2) ◽  
pp. 607-615
Author(s):  
Arman Varmaghani ◽  
William E. Eichinger ◽  
John H. Prueger
Keyword(s):  
Energy Equation ◽  
Minor Components ◽  
Net Radiation ◽  
Obukhov Length ◽  
Available Energy ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation ◽  
Energy Components

Abstract The conventional Food and Agriculture Organization of the United Nations (FAO) Penman–Monteith (P-M) equation requires knowledge of the available energy to estimate reference evapotranspiration (ETo); however, it is common to ignore the minor energy components (MECs). This study was conducted to determine the effect of not including the MECs in the FAO P-M equation. Fifteen-min micrometeorological records of four sites (covered with corn, soybeans, and prairie) in central Iowa, USA, during the years 2007–2012 were investigated. The major/minor components of the energy equation were either measured or estimated by in-situ eddy covariance instruments. It was discovered that, on average, the MECs accounted for at least 13% of daily net radiation, leading to 27% decrease in daily ETo. Therefore, an equation is introduced to estimate MECs as a function of net radiation, air temperature, and Monin–Obukhov length; and another equation is regressed to roughly estimate daily MECs as a function of net radiation and day of the year. The findings in this study suggest a fundamental modification of FAO P-M formula by considering the inclusion of MECs in the energy term.

scholarly journals A Thermodynamically Based Model for Actual Evapotranspiration of an Extensive Grass Field Close to FAO Reference, Suitable for Remote Sensing Application

2016 ◽  
Vol 17 (5) ◽  
pp. 1373-1382 ◽  
Author(s):  
H. A. R. de Bruin ◽  
I. F. Trigo ◽  
F. C. Bosveld ◽  
J. F. Meirink
Keyword(s):  
Global Radiation ◽  
Actual Evapotranspiration ◽  
Net Radiation ◽  
Reference Crop Evapotranspiration ◽  
In Situ Data ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
A Site ◽  
Reference Crop

Abstract A thermodynamically based model is presented to estimate daily actual evapotranspiration (ET) of a grass site closely resembling reference grass as defined by the Food and Agriculture Organization of the United Nations (FAO) under nonadvective conditions, from Meteosat Second Generation (MSG) imagery. The model presented here is derived from the thermodynamic theory by Schmidt combined with an atmospheric boundary layer model. Daily net radiation over the (reference) grass surface is parameterized as a function of global radiation, which can be estimated from MSG observations. It is then shown that ET over the grass area can be estimated using remotely sensed daily global radiation and air temperature as input only. The validation relied on observations gathered in Cabauw, a site closely resembling the reference grass, as defined by the FAO. The comparison with in situ data indicated a bias of 2.8 W m−2 and an RMSE of 7.7 W m−2. The possibility of using the approach developed here to provide reference crop evapotranspiration ETo is discussed. Because of the ambiguousness of ETo definition regarding local advection effects, it should be noted that explicitly advection-free conditions are dealt with. It is pointed out that in semiarid regions local advection cannot be ignored.

scholarly journals How Ångström–Prescott Coefficients Alter the Estimation of Agricultural Water Demand in South Korea

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1851
Author(s):  
Hanseok Jeong ◽  
Rabin Bhattarai ◽  
Syewoon Hwang ◽  
Jae-Gwon Son ◽  
Taeil Jang
Keyword(s):  
South Korea ◽  
Global Solar Radiation ◽  
Water Requirement ◽  
Agricultural Water ◽  
Reference Crop Evapotranspiration ◽  
Agricultural Water Management ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Reference Crop ◽  
Monteith Equation

The Food and Agriculture Organization (FAO) Penman–Monteith equation, recognized as the standard method for the estimation of reference crop evapotranspiration (ET0), requires many meteorological inputs. The Ångström–Prescott (A-P) formula containing parameters (i.e., a and b) is recommended to determine global solar radiation, one of the essential meteorological inputs, but may result in a considerable difference in ET0 estimation. This study explored the effects of A-P coefficients not only on the estimation of ET0, but also on the irrigation water requirement (IWR) and design water requirement (DWR) for paddy rice cultivation, which is the largest consumer of agricultural water in South Korea. We compared and analyzed the estimates of ET0, IWR, and DWR using the recommended (a = 0.25 and b = 0.5) and locally calibrated A-P coefficients in 16 locations of South Korea. The estimation of ET0 using the recommended A-P coefficients produced significant overestimation. The overestimation ranged from 3.8% to 14.0% across the 16 locations as compared to the estimates using the locally calibrated A-P coefficients, and the average overestimation was 10.0%. The overestimation of ET0 corresponded to a variation of 1.7% to 7.2% in the overestimation of the mean annual IWR, and the average overestimation of the IWR was 5.1%. On average, the overestimation was slightly reduced to 4.8% in DWR estimation, since the effect of A-P coefficients on the IWR estimation decreased as the IWR increased. This study demonstrates how the use of A-P coefficients can alter the estimation of ET0, IWR, and DWR in South Korea, which underscores the importance of their proper consideration in agricultural water management.

scholarly journals Lysimeter-Based Water Use and Crop Coefficient of Drip-Irrigated Potato in an Arid Environment

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 756 ◽  
Author(s):  
Alataway ◽  
Al-Ghobari ◽  
Mohammad ◽  
Dewidar
Keyword(s):  
Water Use ◽  
Irrigation Schedule ◽  
Crop Coefficient ◽  
Arid Environment ◽  
Crop Evapotranspiration ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Use Efficiency ◽  
Monteith Equation

The determination of the water requirements and crop coefficient (Kc) of agricultural crops helps to create an appropriate irrigation schedule, and with the effective management of irrigation water. The aim of this research was to estimate the water requirement, Kc, and water-use efficiency (WUE) of potato using non-weighing-type lysimeters in four regions of the Kingdom of Saudi Arabia (Qassiem, Riyadh, Al-Jouf, and Eastern). Our results clearly show that the accumulated values of the measured crop evapotranspiration of potato derived from the lysimeters were 573, 554, 592, and 570 mm, while the accumulated values of the predicted crop evapotranspiration from Penman-Monteith equation based on FAO (Food and Agriculture Organization) were 651, 632, 672, and 647 mm for the Qassiem, Riyadh, Al-Jouf, and Eastern regions, respectively. The Kc values of potato obtained from the lysimeters were Kc initial (0.58, 0.54, 0.50, and 0.52), Kc middle (1.02, 1.05, 1.13, and 1.10), and Kc end (0.73, 0.74, 0.74, and 0.75) for the Qassiem, Riyadh, Al-Jouf, and Eastern regions, respectively. Based on the amount of water used and the yield achieved, the highest WUE (3.6 kg m−3) was observed in the Riyadh region, while the lowest WUE (1.5 kg m−3) was observed in the Al-Jouf region.

scholarly journals Evaluation of Potential Evapotranspiration Based on CMADS Reanalysis Dataset over China

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1126 ◽  
Author(s):  
Ye Tian ◽  
Kejun Zhang ◽  
Yue-Ping Xu ◽  
Xichao Gao ◽  
Jie Wang
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Potential Evapotranspiration ◽  
Swat Model ◽  
Western China ◽  
Reanalysis Dataset ◽  
The North ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation

Potential evapotranspiration (PET) is used in many hydrological models to estimate actual evapotranspiration. The calculation of PET by the Food and Agriculture Organization of the United Nations (FAO) Penman–Monteith method requires data for several meteorological variables that are often unavailable in remote areas. The China Meteorological Assimilation Driving Datasets for the SWAT model (CMADS) reanalysis datasets provide an alternative to the use of observed data. This study evaluates the use of CMADS reanalysis datasets in estimating PET across China by the Penman–Monteith equation. PET estimates from CMADS data (PET_cma) during the period 2008–2016 were compared with those from observed data (PET_obs) from 836 weather stations in China. Results show that despite PET_cma overestimating average annual PET and average seasonal in some areas (in comparison to PET_obs), PET_cma well matches PET_obs overall. Overestimation of average annual PET occurs mainly for western inland China. There are more meteorological stations in southeastern China for which PET_cma is a large overestimate, with percentage bias ranging from 15% to 25% for spring but a larger overestimate in the south and underestimate in the north for the winter. Wind speed and solar radiation are the climate variables that contribute most to the error in PET_cma. Wind speed causes PET to be underestimated with percentage bias in the range −15% to −5% for central and western China whereas solar radiation causes PET to be overestimated with percentage bias in the range 15% to 30%. The underestimation of PET due to wind speed is offset by the overestimation due to solar radiation, resulting in a lower overestimation overall.

scholarly journals CALIBRATION OF THE HARGREAVES-SAMANI EQUATION FOR SPECIFIC PERIODS OF THE YEAR IN THE MUNICIPALITY OF JAÍBA-MG, BRAZIL

2017 ◽  
Vol 25 (5) ◽  
pp. 445-453
Author(s):  
Anunciene Barbosa Duarte ◽  
Lucas Borges Ferreira ◽  
Edson Fagne Dos Santos
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Climatic Conditions ◽  
Crop Water ◽  
Climatic Effects ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Crop Water Demand ◽  
Limited Application ◽  
Monteith Equation

Reference evapotranspiration (ET0) explains the climatic effects on crop water demand. The Food and Agriculture Organization (FAO) recommends the Penman Monteith equation as a standard method for estimating ET0. However, because this equation requires a large amount of meteorological data, it has limited application. An alternative is the Hargreaves-Samani (HS) equation, which only requires air temperature data, and can be calibrated to specifc locations and periods. The present study aimed to calibrate the empirical parameters (coeffcients and exponent) of the HS equation for specifc periods of the year, as well as evaluate the behavior and calibration of this equation throughout the year in the municipality of Jaíba-MG, Brazil. The daily meteorological data from 1996 to 2011 were gathered from a weather station located in the municipality of Jaíba-MG. A general calibration was performed per semester, per season, per month, and during periods with similar climatic conditions. The calibration of the HS equation, in all of the forms studied, promoted better ET0estimations. The calibrations for specifc periods of the year only promoted slight increases in performance in relation to the general calibration, therefore they, in general, presented equal performance to each other.

scholarly journals A Study of Fitting a Swamp Meadow Ecosystem Evapotranspiration to a Model Based on the Penman-Monteith Equation

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
Feng Li ◽  
Bin Wang
Keyword(s):  
Significant Positive Correlation ◽  
Crop Coefficient ◽  
Growing Season ◽  
Linear Increase ◽  
Permafrost Region ◽  
Biotic Factors ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Monteith Equation ◽  
Reference Et

To accurately estimate the magnitude and seasonal dynamics of evapotranspiration (ET) over an important a swamp meadow in the Fenghuoshan permafrost region, we employed the Food and Agriculture Organization- (FAO-) Penman-Monteith (P-M) model. The model was also used to investigate changes in the crop coefficient (kc), which was calculated as the ratio of the measured actual ET (ETafrom the eddy covariance (EC) system) to the reference ET (ET0from the P-M model). The results indicated a reference ET of 900 mm/year from the swamp meadow ecosystem, which was significantly higher than the actual ET (426 mm/year). The reference ET peaked from April to July, while the actual ET was primarily in growing season. The value ofkcexhibited significant seasonal variations within the range 0.3–1.0 with a meankcof 0.55 during the growing season. The dailykcshowed a linear increase withRnandTaand a linear decrease with the VPD. With respect to the biotic factors, the biomass exhibited a significant positive correlation withkc. Thus, a dailykcmodel is developed as a function of the VPD,Rn,Ta, and biomass.

Food waste and dynamic complex systems: The case of Peru and a solution model proposal Part 1: Peruvian Anchoveta (Engraulis ringens)

2020 ◽  
Author(s):  
Carlos A Almenara
Keyword(s):  
United Nations ◽  
Complex Systems ◽  
Revenue Management ◽  
Food Waste ◽  
Intelligent Systems ◽  
Solution Model ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Engraulis Ringens ◽  
The United Nations

[THE MANUSCRIPT IS A DRAFT] According to the Food and Agriculture Organization of the United Nations (FAO, 2020), food waste and losses comprises nearly 1.3 billion tonnes every year, which equates to around US$ 990 billion worldwide. Ironically, over 820 million people do not have enough food to eat (FAO, 2020). This gap production-consumption puts in evidence the need to reformulate certain practices such as the controversial monocropping (i.e., growing a single crop on the same land on a yearly basis), as well as to improve others such as revenue management through intelligent systems. In this first part of a series of articles, the focus is on the Peruvian anchoveta fish (Engraulis ringens).

To the Empire and Beyond

2018 ◽  
Author(s):  
Gregory A. Barton
Keyword(s):  
Second World War ◽  
World War ◽  
Chemical Fertilizers ◽  
Basic Principles ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Organic Farmers ◽  
Southern Rhodesia ◽  
The Government ◽  
Second World

This chapter traces the expansion of industrial agricultural methods after the Second World War. Western governments and the Food and Agriculture Organization pushed for increased use of chemical fertilizers to aid development and resist Soviet encroachment. Meanwhile small groups of organic farmers and gardeners adopted Howard’s methods in the Anglo-sphere and elsewhere in the world. European movements paralleled these efforts and absorbed the basic principles of the Indore Method. British parliament debated the merits of organic farming, but Howard failed to persuade the government to adopt his policies. Southern Rhodesia, however, did implement his ideas in law. Desiccation theory aided his attempts in South Africa and elsewhere, and Louise Howard, after Albert’s death, kept alive a wide network of activists with her publications.

scholarly journals Ensuring Agricultural Sustainability through Remote Sensing in the Era of Agriculture 5.0

2021 ◽  
Vol 11 (13) ◽  
pp. 5911
Author(s):  
Vanesa Martos ◽  
Ali Ahmad ◽  
Pedro Cartujo ◽  
Javier Ordoñez
Keyword(s):  
Remote Sensing ◽  
Sustainable Agriculture ◽  
Information Acquisition ◽  
Industrial Revolution ◽  
Structural Parameters ◽  
Special Focus ◽  
World Population ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Zero Hunger

Timely and reliable information about crop management, production, and yield is considered of great utility by stakeholders (e.g., national and international authorities, farmers, commercial units, etc.) to ensure food safety and security. By 2050, according to Food and Agriculture Organization (FAO) estimates, around 70% more production of agricultural products will be needed to fulfil the demands of the world population. Likewise, to meet the Sustainable Development Goals (SDGs), especially the second goal of “zero hunger”, potential technologies like remote sensing (RS) need to be efficiently integrated into agriculture. The application of RS is indispensable today for a highly productive and sustainable agriculture. Therefore, the present study draws a general overview of RS technology with a special focus on the principal platforms of this technology, i.e., satellites and remotely piloted aircrafts (RPAs), and the sensors used, in relation to the 5th industrial revolution. Nevertheless, since 1957, RS technology has found applications, through the use of satellite imagery, in agriculture, which was later enriched by the incorporation of remotely piloted aircrafts (RPAs), which is further pushing the boundaries of proficiency through the upgrading of sensors capable of higher spectral, spatial, and temporal resolutions. More prominently, wireless sensor technologies (WST) have streamlined real time information acquisition and programming for respective measures. Improved algorithms and sensors can, not only add significant value to crop data acquisition, but can also devise simulations on yield, harvesting and irrigation periods, metrological data, etc., by making use of cloud computing. The RS technology generates huge sets of data that necessitate the incorporation of artificial intelligence (AI) and big data to extract useful products, thereby augmenting the adeptness and efficiency of agriculture to ensure its sustainability. These technologies have made the orientation of current research towards the estimation of plant physiological traits rather than the structural parameters possible. Futuristic approaches for benefiting from these cutting-edge technologies are discussed in this study. This study can be helpful for researchers, academics, and young students aspiring to play a role in the achievement of sustainable agriculture.

scholarly journals Strengthening implementation of antimicrobial resistance national action plans

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
M Anderson ◽  
K Schulze ◽  
A Cassini ◽  
D Plauchoras ◽  
E Mossialos
Keyword(s):  
Antimicrobial Resistance ◽  
Policy Design ◽  
Animal Health ◽  
Monitoring And Evaluation ◽  
Basic Structure ◽  
Infection Prevention And Control ◽  
Action Plans ◽  
Governance Framework ◽  
Food And Agriculture ◽  
Food And Agriculture Organization

Abstract Antimicrobial resistance is one of the major challenges of our time. Countries use national action plans as a mechanism to build engagement among stakeholders and coordinate a range of actions across human, animal, and environmental health. However, implementation of recommended policies such as stewardship of antimicrobials, infection prevention and control, and stimulating research and development of novel antimicrobials and alternatives remains inconsistent. Improving the quality of governance within antimicrobial resistance national action plans is an essential step to improving implementation. To date, no systematic approach to governance of national action plans on AMR exists. To address this issue, we aimed to develop the first governance framework to offer guidance for both the development and assessment of national action plans on AMR. We reviewed health system governance framework reviews to inform the basic structure of our framework, international guidance documents from WHO, the Food and Agriculture Organization, the World Organisation for Animal Health, and the European Commission, and sought the input of 25 experts from international organisations, government ministries, policy institutes, and academic institutions to develop and refine our framework. The framework consists of 18 domains with 52 indicators that are contained within three governance areas: policy design, implementation tools, and monitoring and evaluation. Countries must engage with a cyclical process of continuous design, implementation, monitoring and evaluation to achieve these aims.

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