Search results for " Energy Balance"

Critical analysis of empirical ground heat flux equations on a cereal field using micrometeorological data

2009

The rate at which the net radiation is transferred to the soil as ground heat flux varies with surface characteristics. Surface energy balance algorithms use empirical relationships taking into account the effects of the canopy cover to insulate the soil through vegetation indexes, the soil capacity to absorb incoming net radiation via the albedo, and the surface temperature promoting the energy transfer. However empirical relationships are often dependent on local conditions, such as the soil humidity and vegetation type. Ground heat flux assumes a minimum value in case of full canopy cover and a maximum value for dry bare soil. Aim of the present research is the critical analysis of some …

Assessing actual evapotranspiration via surface energy balance aiming to optimize water and energy consumption in large scale pressurized irrigation …

2017

Satellite imagery provides a dependable basis for computational models that aimed to determine actual evapotranspiration (ET) by surface energy balance. Satellite-based models enables quantifying ET over large areas for a wide range of applications, such as monitoring water distribution, managing irrigation and assessing irrigation systems’ performance. With the aim to evaluate the energy and water consumption of a large scale on-turn pressurized irrigation system in the district of Aguas Nuevas, Albacete, Spain, the satellite-based image-processing model SEBAL was used for calculating actual ET. The model has been applied to quantify instantaneous, daily, and seasonal actual ET over high- …

Mass and surface energy balance approaches for monitoring water stress in vineyards

2013

Abstract Tree crops are representing one of most widespread agricultural systems in Mediterranean regions, thus contributing in a substantial way to the economy and productivity of primary sectors of the countries interested. Besides the aspects concerning their economical relevance, tree crops like vineyards, olive and orange orchards are also typical elements of the Mediterranean landscape, and their ecological role has been recently revitalised in consideration of their function as carbon sinks for the Kyoto agreement. The environmental and economical sustainability of these agricultural systems in arid and semi-arid zones has to cope with the availability and management of water resourc…

Time-domain based feature space at FLUXNET sites for vegetation patterns identification

2019

Monitoring the flux transfer of mass and energy occurring within the soil-plant-atmosphere continuum is a pivotal key for understanding hydrological and vegetation relationships. Average daily values of the Priestley - Taylor (PT) parameter were calculated for 4 eddy covariance (EC) flux tower sites from FLUXNET network, characterized by different vegetation features, over the 2010-12 reference period. Site-by-site feature spaces (built by difference in diurnal and night-time land surface temperature versus enhanced vegetation index, ΔLST-EVI) were obtained by combining satellite data (MODIS) and observed PT parameter (ϕ) retrieved by FLUXNET surface energy balance (SEB) fluxes. The results…

Effect of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) on Hormones of Energy Balance in a TCDD-Sensitive and a TCDD-Resistant Rat Strain

2014

One of the hallmarks of the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a drastically reduced feed intake by an unknown mechanism. To further elucidate this wasting syndrome, we followed the effects of a single large dose (100 μg/kg) of TCDD on the serum levels of several energy balance-influencing hormones, clinical chemistry variables, and hepatic aryl hydrocarbon receptor (AHR) expression in two rat strains that differ widely in their TCDD sensitivities, for up to 10 days. TCDD affected most of the analytes in sensitive Long-Evans rats, while there were few alterations in the resistant Han/Wistar strain. However, analyses of feed-restricted unexposed Long-Evans rats i…

A critical analysis of three remote sensing-based actual evapotranspiration assessment methods over sparse crops agricultural areas

2010

During last two decades the increasing availability of remotely sensed acquisitions in the thermal infrared part of the spectrum has encouraged hydrologist community to develop models and methodologies based on these kind of data. The aim of this paper is to compare three methods developed to assess the actual evapotranspiration spatial distribution by means of remote sensing data. The comparison was focused on the differences between the "single" (SEBAL) and "two" source (TSEB) surface energy balance approaches and the S-SEBI semi-empirical method. The first assumes a semiempirical internal calibration for the sensible heat flux assessment; the second uses a physically based approach in or…

Metabolic Impacts of Confinement during the COVID-19 Pandemic Due to Modified Diet and Physical Activity Habits

2020

While the detrimental effects of a chronic positive energy balance due to a sedentary lifestyle have been well established, the impacts of a short period of abruptly reduced physical activity and overeating arising from strict confinement due to the COVID-19 pandemic will soon start to emerge. To reasonably anticipate major consequences according to the available evidence, we hereby review the literature for studies that have explored the health impacts of several weeks of a reduction in physical activity and daily step-count combined with modified eating habits. These studies identify as main metabolic consequences increases in insulin resistance, total body fat, abdominal fat and inflamma…

Assessing opportunities for water savings in large-scale pressurized irrigation systems using actual evapotranspiration retrieved by surface energy b…

Remote sensing allows the observation of large land stretches and the acquisition of worthwhile information that can be used efficaciously in agro-hydrologic systems. Satellite imagery associated to computational models provide a reliable resource in estimating evapotranspiration (ET) fluxes based on surface energy balance. On irrigated crops, quantifying the spatial distribution of actual ET enables a broad range of applications such as irrigation management, monitoring water distribution, assessing crop water status and irrigation system performance. The general objective of the research was to propose a methodology to estimate ET by using Landsat Thematic Mapper (TM) images and surface e…

Assessing the performance of a large-scale irrigation system by estimations of actual evapotranspiration obtained by Landsat satellite images resampl…

2019

Abstract Remote sensing techniques allow monitoring the Earth surface and acquiring worthwhile information that can be used efficiently in agro-hydrological systems. Satellite images associated to computational models represent reliable resources to estimate actual evapotranspiration fluxes, ETa, based on surface energy balance. The knowledge of ETa and its spatial distribution is crucial for a broad range of applications at different scales, from fields to large irrigation districts. In single plots and/or in irrigation districts, linking water volumes delivered to the plots with the estimations of remote sensed ETa can have a great potential to develop new cost-effective indicators of irr…

Comparison between energy balance and mass balance models for actual evapotranspiration assessment

2009

The assessment of the water needs for a specific crop has a fundamental importance in the management of water resources. The application of empirical models able to retrieve estimates of the actual evapotranspiration (ETa) to assess the need for water could give a valid tool for the planning of water supply, avoiding unnecessary water losses. In this context, two independent models for estimating actual evapotranspiration were compared. The first model is based on an energy balance and uses remotely sensed data and ancillary data from weather stations to assess the ETa. The second model also uses remotely sensed data and climatic data on a daily basis from a weather network. Field measureme…