42,591 research outputs found
Evapotranspiração de referência entre métodos de pennan-monteith e thorthwaite no estado de Santa Catarina
No full textTCC (graduação em Agronomia) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, 2010O estudo da evapotranspiração é de grande importância na avaliação da severidade, distribuição e freqüência dos déficits hídricos, na elaboração de projetos e no manejo de sistemas de irrigação e drenagem. O trabalho teve como objetivo principal correlacionar a evapotranspiração de referência (ETo) entre os métodos de Penman-Monteith (PM) e Thornthwaite (TH) de 22 estações meteorológicas localizadas em Santa Catarina. O método da Regressão Linear foi utilizado para analisar a correlação existente entre a ETo estimada pelos dois métodos na escala decendial e mensal, e na análise de sensibilidade. Para analisar quais médias decendiais da ETo (PM) são consideradas diferentes de outras localizadas numa mesma região climática, foi utilizado o método de Tukey. Os resultados mostram que a média decendial de todas as estações da mesma região não diferiram estatisticamente entre si, indicando que a ETo (PM) obtida em um ponto, pode ser aplicado em qualquer outro ponto, desde que estejam na mesma região climática. A comparação da ETo estimada pelos dois métodos indicam altas e significativas correlações, tanto na escala mensal quanto na decendial, possibilitando, assim, estimar a ETo (PM) apenas com dados da temperatura do ar
Portrait of R. G. Menzies, Prime Minister of Australia [picture] /
No full textTitle from inscription on reverse.; Condition: Good.; Inscriptions: "Mr. R. G. Menzies, Prime Minister of Australia ... Australian News & Information Bureau photograph, L13044" --Printed on label on reverse.; "Originally taken in the Studio of Dickinson-Monteith, Collins Street, Melbourne, ca. 1950."--Information supplied by former employee of Studio, Luke Bryant.; Neg. No. 19
Mapping evapotranspiration on vineyards: A comparison between Penman-Monteith and energy balance approaches for operational purposes
No full textEstimation of evapotranspiration (ET) in Sicilian vineyard is an emerging issue since these agricultural systems are more and more converted from rainfed to irrigated conditions, with significant impacts on the management of the scarce water resources of the region. The choice of the most appropriate methodology for assessing water use in these systems is still an issue of debating, due to the complexity of canopy and root systems and for their high spatial fragmentation. In vineyards, quality and quantity of the final product are dependent on the controlled stress conditions to be set trough irrigation. This paper reports an application of the well-known Penman-Monteith approach, applied in a distributed way, using high resolution remote sensing data to map the potential evapotranspiration (ETp). In 2008 a series of airborne multispectral images were acquired on "Tenute Rapitalà", a wine farm located in the northwest of Sicily. Five airborne remote sensing scenes were collected using a SKY ARROW 351 650 TC/TCNS aircraft, at a height of about 1000 m a.g.l. The acquisitions were performed encompassing a whole phenological period, period between June and September 2008 (approximately every three weeks). The platform had on board a multi-spectral camera with 3 spectral bands at green (G, 530-570 nm), red (R, 650-690 nm) and near infrared (NIR, 767-832 nm) wavelengths, and a thermal camera with a broad band in the range 7.5-13 μm. The nominal pixel resolution was approximately 0.7 m for VIS/NIR acquisitions, and 1.7 m for the thermal-IR data. Field data were acquired simultaneously to airborne acquisitions. These data include spectral reflectances in VIS-NIR-SWIR (shortwave infrared), leaf area index (LAI), soil moisture at different depths (both in row and below plants). Moreover, meteo variables were measured by a standard weather station whereas fluxes were measured by means of an Eddy correlation tower located within the field. The VIS-NIR bands were atmospherically corrected and calibrated in order to calculate albedo, NDVI and LAI, which represented the distributed inputs of the Penman-Monteith algorithm. Moreover a sensitivity analysis has been carried out on input parameters (such as albedo). A sensitivity analysis was carried out to highlight the variability of outputs (such as ETp) on the accuracy in the parameters assessment obtainable using high spatial resolution airborne images. Scale effects have been also investigated by means of an artificial degradation of images spatial resolution. Finally the relationship between stress factor evaluated as the ratio between actual and reference ET and pre-dawn leaf water potential has been also investigated. © 2012 SPIE
The dialogue between the author and the hero in the “Notes” of G. R. Derzhavin
No full textВ центре внимания автора статьи «Записки» Г. Р. Державина, представляющие по своей сути его автобиографию. Труд этот был создан на закате жизни, он включает все важнейшие события жизни Г. Р. Державина, поэта и государственного деятеля. Рассказ ведется от третьего лица, что придает особую атмосферу повествованию, выстраивается своеобразный диалог между автором и героем, все это и является предметом исследования автора статьи.The focus of the author of the article “Notes” G. R. Derzhavin, representing in essence his autobiography. This work was created at the end of his life; it includes all the most important events in the life of G. R. Derzhavin, poet and statesman. The story is told in a third person, which gives a special atmosphere to the story, a certain dialogue emerges between the author and the hero, all this is the subject of the author's research
MONTPEL: A multi-component Penman-Monteith energy balance model
No full textCorresponding author: [email protected] (R. Albasha).International audienceMechanistic modelling is gradually replacing empiricism in crop models, focusing on leaf-level physiological processes. This shift necessitates simulating crop surface temperature at infra-canopy sub-daily scales but many crop models still rely on empirical formulations for canopy temperature estimation, typically on a daily basis. We developed MONTPEL, a multi-component Penman-Monteith model that allows simulating the crop energy balance with flexible canopy representations ("BigLeaf" vs. "Layered", "Lumped" vs. "Sunlit-Shaded") and accounts for atmospheric stability conditions. We analyzed the model behavior, sensitivity and accuracy, using measurements from four wheat (Triticum aestivum L.) experiments conducted under varying pedoclimatic and water stress conditions. Measurements included hourly energy balance terms (total net radiation, soil heat flux, sensible and latent energy fluxes), hourly temperature of the canopy surface or of leaves at different depths inside the canopy, and sunlit and shaded leaf temperatures around solar noon at different dates. MONTPEL reproduced the measured energy balance terms with a root mean square error (RMSE) between 21 and 87 Wm -2 and a coefficient of determination (R 2 ) exceeding 0.65. The model's accuracy in simulating canopy temperature, with RMSE ≤ 2.2 • C and R 2 ≥ 0.92, remained consistent regardless of measurement scale. Adjusting the aerodynamic resistance for atmospheric stability minimized simulated canopy temperature errors, notably in semi-arid conditions. Crop latent energy flux and temperature were most sensitive to the maximal stomatal conductance (g s, max ) parameter. However, using a single g s, max value across the simulated experiments yielded satisfactory results, suggesting a weak sensitivity to the temporal and site-to-site variability of g s, max . Distinguishing sunlit from shaded canopy fractions systematically resulted in lower latent energy fluxes compared to "Lumped" canopy representation results. Analysis identified limitations in the multi-component approach, particularly an unrealistic uniform temperature shift across leaf layers when soil surface temperature changes
Supplemental Material - An Examination of the Use of Large Language Models to Aid Analysis of Textual Data
No full textSupplemental Material for An Examination of the Use of Large Language Models to Aid Analysis of Textual Data by Robert H. Tai, Lillian R. Bentley, Xin Xia, Jason M. Sitt, Sarah C. Fankhauser, Ana M. Chicas-Mosier, and Barnas G. Monteith in International Journal of Qualitative Methods</p
Mapping evapotranspiration on vineyards: a comparison between Penman-Monteith and Energy Balance approaches for operational purposes
No full textEstimation of evapotranspiration (ET) in Sicilian vineyard is an emerging issue since these agricultural systems are more and more converted from rainfed to irrigated conditions, with significant impacts on the management of the scarce water resources of the region. The choice of the most appropriate methodology for assessing water use in these systems is still an issue of debating, due to the complexity of canopy and root systems and for their high spatial fragmentation. In vineyards, quality and quantity of the final product are dependent on the controlled stress conditions to be set trough irrigation. This paper reports an application of the well-known Penman-Monteith approach, applied in a distributed way, using high resolution remote sensing data to map the potential evapotranspiration (ETp). In 2008 a series of airborne multispectral images were acquired on "Tenute Rapitalà", a wine farm located in the northwest of Sicily. Five airborne remote sensing scenes were collected using a SKY ARROW 351 650 TC/TCNS aircraft, at a height of about 1000 m a.g.l.. The acquisitions were performed encompassing a whole phenological period, period between June and September 2008 (approximately every three weeks). The platform had on board a multi-spectral camera with 3 spectral bands at green (G, 530-570 nm), red (R, 650-690 nm) and near infrared (NIR, 767-832 nm) wavelengths, and a thermal camera with a broad band in the range 7.5-13 μm. The nominal pixel resolution was approximately 0.7 m for VIS/NIR acquisitions, and 1.7 m for the thermal-IR data. Field data were acquired simultaneously to airborne acquisitions. These data include spectral reflectances in VIS-NIR-SWIR (shortwave infrared), leaf area index (LAI), soil moisture at different depths (both in row and below plants). Moreover, meteo variables were measured by a standard weather station whereas fluxes were measured by means of an Eddy correlation tower located within the field. The VIS-NIR bands were atmospherically corrected and calibrated in order to calculate albedo, NDVI and LAI, which represented the distributed inputs of the Penman-Monteith algorithm. Moreover a sensitivity analysis has been carried out on input parameters (such as albedo). A sensitivity analysis was carried out to highlight the variability of outputs (such as ETp) on the accuracy in the parameters assessment obtainable using high spatial resolution airborne images. Scale effects have been also investigated by means of an artificial degradation of images spatial resolution. Finally the relationship between stress factor evaluated as the ratio between actual and reference ET and pre-dawn leaf water potential has been also investigated
Evaluación lisimétrica de la evapotranspiración de referencia semihoraria calculada con el método FAO Penman-Monteith
No full textEn XVIII Congreso Nacional de Riegos, Huelva, 2000.[ES] En este trabajo se efectúa una evaluación del método FAO Penman-Monteith para la estima de valores semihorarios de evapotranspiración de referencia ( ET 0 ) bajo las condiciones semiáridas del Valle del Ebro, mediante su comparación con valores medidos en un lisímetro de pesada. Se han calculado valores de ET 0 con cuatro variantes de dicho método. En tres de ellas ( ETPM1, ETPM2, ETPM3 ), la radiación neta (R net ) y el flujo de calor hacia el suelo ( G) se han estimado como indica la Organización de las Naciones Unidas para la Agricultura y la Alimentación ( FAO) (Allen et al., 1998) y en la cuarta ( ETPM4 ) se han utilizado valores medidos de R net y G. En el caso de ETPM1 , se han utilizado valores medidos de radiación solar ( R s ) y un factor de turbidez k tb = 1.0 para estimar la radiación solar en días despejados (R so ). En el caso de ETPM2 , se ha usado un factor k tb = 0.85, mientras que en el caso de ETPM3 , los valores medidos de R s se han multiplicado por la pendiente de regresión entre R s medida en días despejados y R so . Los resultados indican que no existen diferencias significativas entre las variantes ETPM1 y ETPM2 . Se han observado diferencias significativas con la variante ETPM3 , pero probablemente dichas diferencias se reducirían fuertemente si los valores medidos de R s sólo se hubiesen modificado para valores superio res a 700 W m -2 . Los resultados de la variante ETPM4 fueron diferentes a los de los otros casos, y sugieren que el procedimiento de la FAO sobrestima R net . Los resultados de este trabajo apuntan a que la advección fue la principal causa de la infraestimación observada: hasta un 15 % en el verano y un 4-5 % en el otoño.[EN] In this work, the FAO Penman -Monteith method for estimating semi-hourly values of reference evapotranspiration ( ET 0 ), under the semiarid conditions of Ebro valley, was evaluated by comparison with measured values using a weighing lysimeter. Four alternatives of the FAO Penman-Monteith were studied. In three of them (ETPM1, ETPM2, ETPM3 ), net radiation (R net ) and soil heat flux (G) were estimated as suggested by the U nited Nations Food and Agricultural Organization ( FAO) (Allen et al., 1998). In the fourth case (ETPM4 ), ET 0 was computed using measured values of R net and G. For ETPM1 , net radiation was estimated using measured values of solar radiation (R s ) and a turbidity coefficient k tb = 1.0 for estimation of clear sky solar radiation (R so ). For ETPM2 , a coefficient k tb = 0.85 was used, whereas for ETPM3, measured values of R s were multiplied for the slope of regression between measured R s and computed R so values for clear sky days. No significant differences between ETPM1 and ETPM2 were observed. For ETPM3 , differences were significant. However, such differences would reduce strongly if measured values of R s had only been modified for values above 700 W m -2 . The results for ETPM4 were different to those of the other cases and suggest that the FAO method overestimates R net . These results point out that advection was the main cause of the observed underestimation: as much as 15 % on summer and 4-5 % on fall
Quantifying the uncertainties of transpiration calculations with the Penman-Monteith equation under different climate and optimum water supply conditions
No full textThe uncertainties of transpiration calculations with the Penman-Monteith equation were quantified under different climate conditions of Brazil, Germany and Israel using maize as a common crop type. All experiments were carried out under non-limiting growing conditions. Canopy resistance was determined by scaling to canopy level specific relations between in situ measurements of incident radiation and stomatal conductance using a light penetration model. The model was tested against heat-pulse measured sap flow in plant stems. The root mean square error (RMSE) of daily calculated transpiration minus measured sap flow was 0.4 mm/day. It was dominated by its variance component (variance = 0.2 {min/day}(2); bias = 0.0 mm/day). Calculated transpiration closely matched the measured trends at the three locations. No significant differences were found between seasons and locations. Uncertainties of canopy conductance parameterizations led to errors of up to 2.1 mm/day. The model responded most sensitively to a 30% change of net radiation (absolute bias error = 1.6 mm/day), followed by corresponding alterations of canopy resistances (0.8 mm/day), vapour pressure deficits (0.5 mm/clay) and aerodynamic resistances (0.34 mm/day). Measured and calculated 30-min or hourly averaged transpiration rates are highly correlated (r(2) = 0.95; n = 10634), and the slope of the regression line is close to unity. The overall RMSE of calculated transpiration minus measured sap flow was 0.08 mm/h and was dominated by its variance component (0.005 {mm/h}(2)). Measured sap flow consistently lagged behind calculated transpiration, because plant hydraulic capacitance delays the change of leaf water potential that drives water uptake. Calculated transpiration significantly overestimated sap flow during morning hours (mean = 0.068 mm/h, n = 321) and underestimated it during afternoon hours (mean = -0.065 mm/h; n = 316). The Penman-Monteith approach as implemented in the present study is sufficiently sensitive to detect small differences between transpiration and water uptake and provides a robust tool to manage plant water supply under unstressed conditions. (C) 2009 Elsevier B.V. All rights reserved
Gravastars in f(R, G) gravity
No full textThis paper is focused on the study of gravitational vacuum stars or, briefly, gravastars in f(R, G) gravity, where R and G stand for the Ricci scalar and Gauss–Bonnet invariant term, respectively. Due to the involvement of highly non-linear differential equations, solutions are found by using some appropriate numerical techniques. The main structure of gravastars has been discussed according to core, shell, and exterior regions for a well-known f(R, G) gravity cosmological model. Mass–radius evolution is described graphically for the considered gravastar, and it is shown that the mass is directly proportional to the radius.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
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