Search results for "Remote Sensing"
showing 10 items of 1262 documents
The SMOS mediterranean ecosystem L-band characterisation experiment (MELBEX) over natural shrubs
2010
10 páginas, 5 figuras, 7 tablas.
Monitoring temporal changes in the spatial patterns of a Mediterranean shrubland using Landsat TM images
2001
Summary The overall goal of this study is to understand the structure and function of a Mediterranean shrubland at landscape scale by means of satellite images and GIS. Specifically, to assess the sensitivity of several spatial statistics to characterise landscape pattern, measure fragmentation and quantify the change through time. We study the landscape structure of a Mediterranean shrubland located in the east part of Spain (Valencia) and the change in spatial patterns of different shrubs types from 1984 to 1994. To accomplish these objectives, we used 10 Landsat™ images from 1984 to 1994 (except 1988) to which a geometric correction and an atmospheric normalization was applied. In additi…
Impact of Initial Soil Temperature Derived from Remote Sensing and Numerical Weather Prediction Datasets on the Simulation of Extreme Heat Events
2016
Extreme heat weather events have received increasing attention and has become of special importance as they can remarkably affect sectors as diverse as public health, energy consumption, water resources, natural biodiversity and agricultural production. In this regard, summer temperatures have become a parameter of essential interest under a framework of a hypothetical increase in the number of intense-heat conditions. Thus, their forecast is a crucial aspect bearing in mind a mitigation of the effects and impacts that these intense-heat situations could produce. The current work tries to reach a better understanding of these sorts of situations that are really common over the Western Medit…
Retrieval and assessment of CO2 uptake by mediterranean ecosystems using remote sensing and meteorological data
2014
Reseña de tesis doctoral
Identification of Morphological Biosignatures in Martian Analogue Field Specimens Using In Situ Planetary Instrumentation
2008
International audience; We have investigated how morphological biosignatures (i.e., features related to life) might be identified with an array of viable instruments within the framework of robotic planetary surface operations at Mars. This is the first time such an integrated lab-based study has been conducted that incorporates space-qualified instrumentation designed for combined in situ imaging, analysis, and geotechnics ( sampling). Specimens were selected on the basis of feature morphology, scale, and analogy to Mars rocks. Two types of morphological criteria were considered: potential signatures of extinct life ( fossilized microbial filaments) and of extant life (crypto-chasmoendolit…
Scaling carbon fluxes from eddy covariance sites to globe: synthesis and evaluation of the FLUXCOM approach
2020
FLUXNET comprises globally distributed eddy-covariance-based estimates of carbon fluxes between the biosphere and the atmosphere. Since eddy covariance flux towers have a relatively small footprint and are distributed unevenly across the world, upscaling the observations is necessary to obtain global-scale estimates of biosphere–atmosphere exchange. Based on cross-consistency checks with atmospheric inversions, sun-induced fluorescence (SIF) and dynamic global vegetation models (DGVMs), here we provide a systematic assessment of the latest upscaling efforts for gross primary production (GPP) and net ecosystem exchange (NEE) of the FLUXCOM initiative, where different machine learning methods…
Comparison of evapotranspiration estimates by NOAA-AVHRR images and aircraft flux measurements in a semiarid region of Spain.
1998
Abstract This paper is intended to show how to aggregate two different remote-sensing techniques carried out in the framework of the European-Union funded project EFEDA (European Field Experiment in a Desertification-threatened Area). One of these is based on satellite measurements, and the other on aircraft flux measurements. The aim of putting together both methodologies was to determine regional evapotranspiration as a major component of the water balance in Castilla-La Mancha, a semiarid region in southeast Spain. The basis for the satellite approach is using temperature information collected by the Advanced Very High-Resolution Radio- meter (AVHRR) sensor on board the National Oceanic …
A Comparative Study of Land Surface Emissivity Retrieval from NOAA Data
2001
Abstract A comparative study has been carried out on the most recent algorithms for the estimation of land surface emissivity (ϵ) using Advanced Very High Resolution Radiometer (AVHRR) data. Three of the algorithms are based on the Temperature-Independent Spectral Indices (TISI) concept using atmospherically corrected channels 3, 4, and/or 5, namely: (1) TISI BL , (2) TS-RAM, and (3) Δ day. The fourth is a simplified method based on the estimation of ϵ using atmospherically corrected data in the visible and near-infrared channels, called Normalized Difference Vegetation Index (NDVI) Thresholds Method (NDVI THM ). This method integrates a wide spectral data set of bare soil reflectivity meas…
Testing two temporal upscaling schemes for the estimation of the time variability of the actual evapotranspiration
2015
Temporal availability of grapes actual evapotranspiration is an emerging issue since vineyards farms are more and more converted from rainfed to irrigated agricultural systems. The manuscript aims to verify the accuracy of the actual evapotranspiration retrieval coupling a single source energy balance approach and two different temporal upscaling schemes. The first scheme tests the temporal upscaling of the main input variables, namely the NDVI, albedo and LST; the second scheme tests the temporal upscaling of the energy balance output, the actual evapotranspiration. The temporal upscaling schemes were implemented on: i) airborne remote sensing data acquired monthly during a whole irrigatio…
Automatic generation of emissivity maps on a European scale
2009
The remote sensing measurement of the land surface temperature from satellites provides an overview of this magnitude on a continuous and regular basis. The study of its evolution in time and space is a critical factor in many scientific fields such as weather forecasting, detection of forest fires, climate change, and so on. The main problem of making this measurement from satellite data is the need to correct the effects of the atmosphere and the surface emissivity. In this work, these corrections have been made using a split-window algorithm. The aim was to define an enhanced vegetation cover method and develop a system that used it, in order to automatically generate maps of land surfac…