Search results for "Transpiration"
showing 10 items of 240 documents
Towards Estimation of Seasonal Water Dynamics of Winter Wheat from Ground-Based L-Band Radiometry
2021
The vegetation optical depth (VOD) parameter contains information on plant water content and biomass, and can be estimated alongside soil moisture from currently operating satellite radiometer missions, such as SMOS (ESA) and SMAP (NASA). The estimation of water fluxes, such as plant water uptake (PWU) and transpiration rate (TR), from these Earth system parameters (VOD, soil moisture) requires assessing potential (suction tension) gradients of water and flow resistances in the soil, the vegetation and the atmosphere, yet it remains an elusive challenge especially on global scale. Here, we used a field-scale experiment to test mechanistic models for the estimation of seasonal water fluxes (…
Discriminating irrigated and rainfed olive orchards with thermal ASTER imagery and DART 3D simulation
2009
Article in Press
Assessing the suitability of American National Aeronautics and Space Administration (NASA) agro-climatology archive to predict daily meteorological v…
2017
Abstract For decades, the importance of evapotranspiration processes has been recognized in many disciplines, including hydrologic and drainage studies, irrigation systems design and management. In this research, the suitability of the Prediction Of Worldwide Energy Resource database published by the American National Aeronautics and Space Administration (POWER-NASA), to estimate daily meteorological variables and ET 0 was assessed in Sicily, Italy, for the period 2006–2014, based on ground data measured by a network of climate stations belonging to the regional Agro-meteorological Information Service (SIAS). After comparing the climate data (minimum, T min , maximum, T max , and average, T…
Wind speed and temperature trends impacts on reference evapotranspiration in Southern Italy
2014
In this study, the impacts of both temperature and wind speed trends on reference evapotranspiration have been assessed using as a case study the Southern Italy, which present a wide variety of combination of such climatic variables trends in terms of direction and magnitude. The existence of statistically significant trends in wind speed and temperature from observational datasets, measured in ten stations over Southern Italy during the period 1968–2004, has been investigated. Time series have been examined using the Mann–Kendall nonparametric statistical test in order to detect possible evidences of wind speed and temperature trends at different temporal resolution and significance level.…
Obtaining the three-dimensional structure of tree orchards from remote 2D terrestrial LIDAR scanning
2009
In recent years, LIDAR (light detection and ranging) sensors have been widely used to measure environmental parameters such as the structural characteristics of trees, crops and forests. Knowledge of the structural characteristics of plants has a high scientific value due to their influence in many biophysical processes including, photosynthesis, growth, CO2-sequestration and evapotranspiration, playing a key role in the exchange of matter and energy between plants and the atmosphere, and affecting terrestrial, above-ground, carbon storage. In this work, we report the use of a 2D LIDAR scanner in agriculture to obtain three-dimensional (3D) structural characteristics of plants. LIDAR allows…
The Added-Value of Remotely-Sensed Soil Moisture Data for Agricultural Drought Detection in Argentina
2021
In countries where the economy relies mostly on agricultural-livestock activities, such as Argentina, droughts cause significant economic losses. Currently, the most-used drought indices by the Argentinian National Meteorological and Hydrological Services are based on field precipitation data, such as the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI). In this article, we explored the performance of the satellite-based soil moisture agricultural drought index (SMADI) for agricultural drought detection in Argentina during 2010-2015, and compared it with the one from the standardized soil moisture anomalies (SSMA), SPI and SPEI (at on…
A Simple method for estimating the latent heat flux over grass from radiative bowen ratio
1998
Abstract The evaluation of crop evapotranspiration from infrared temperature is usually calculated as the residual component of the surface energy balance. This method has given good results over a full grass canopy cover with unstressed transpiration, in spite of the not well understood meaning of the aerodynamic resistance needed. A simple and more accurate method, which determines the Bowen ratio (β) and the latent heat flux (λE) over a reference grass area without knowledge of surface resistances, is proposed. The proportionality between β and a radiative Bowen ratio βs is shown. The radiative Bowen ratio is derived from surface and air temperatures and vapor pressure. This relationship…
Sources of water vapour contributing to the Elbe flood in August 2002-A tagging study in a mesoscale model
2009
In this study we investigate the contribution of various moisture sources to the Elbe flood that occurred in Central Europe during August 2002. An 8-day simulation with the mesoscale numerical weather prediction model CHRM, including newly implemented water vapour tracers, has been performed. According to the simulation, rather than drawing moisture from one single dominant source region, water vapour from widely separated moisture sources contributed to the extreme precipitation in the most affected area, notably at distinct, subsequent periods of time, and each in significant amounts. These moisture sources include the Atlantic and Mediterranean ocean areas inside the model domain, evapot…
Estimation of the spatially distributed surface energy budget for AgriSAR 2006, part II : Integration of remote sensing and hydrologic modeling
2011
In most hydrologic modeling studies, the hypothesis is made that an improvement in the modeled soil moisture leads to an improvement in the modeled surface energy balance. The objective of this paper is to assess whether this hypothesis is true. The study was performed over the winter wheat fields in the AgriSAR 2006 domain. Remotely sensed soil moisture values and latent heat fluxes were used, in combination with in situ observations. First, the land cover and saturated subsurface flow parameters were estimated using the in situ observations. A spatially distributed model simulation was then performed, for which the Brooks-Corey parameters were derived from a soil texture map, and of which…
Multilayer modelling of ozone fluxes on winter wheat reveals large deposition on wet senescing leaves
2015
Understanding how ozone is deposited on vegetation canopies is needed to perform tropospheric greenhouse gas budgets and evaluate the associated damage on vegetation. In this study, we propose a new multilayer scheme of ozone deposition on vegetation canopies that predicts stomatal, cuticular and soil deposition pathways separately. This mechanistic ozone deposition scheme is based on the multi-layer, multi-leaf mass and energy transfer model MuSICA. This model was chosen because it explicitly simulates the processes of rain interception, through fall and evaporation at different depths within the vegetation canopy, so that ozone deposition on wet leaf cuticles can be explicitly modelled wi…