Search results for "Atmosfera"
showing 10 items of 45 documents
Atmospheric correction algorithm for POLDER data. Case study: DAISEX 1999 campaign
2006
RESUMEN Este artículo presenta un algoritmo para corregir los efectos de la atmósfera de la reflectividad multiangulare hiperespectral de POLDER, prestando especial atención al efecto de los aerosoles. Los datos fueron adquiridos durante la campaña DAISEX-99 de la Agencia Espacial Europea. El algoritmo está basado en la inversión de la reflectividad medida en dos pasos. Primero, se invierte la reflectividad de POLDER para determinar los tres parámetros de la función de distribución de la reflectividad bidireccional de la superficie (BRDF). Estos valores son los datos de entrada de la superficie para el segundo paso. En este segundo paso, invertimos de nuevo la reflectividad para obtener tre…
Comparing different profiles to characterize the atmosphere for three MODIS TIR bands
2015
Abstract Accurate land surface temperature (LST) retrievals from sensors aboard orbiting satellites are dependent on the corresponding atmospheric correction, especially in the thermal infrared (TIR) spectral domain (8–14 μm). To remove the atmospheric effects from at-sensor measured radiance in the TIR range it is needed to characterize the atmosphere by means of three specific variables: the upwelling path and the hemispherical downwelling radiances plus the atmospheric transmissivity. Those variables can be derived from the previous knowledge of vertical atmospheric profiles of air temperature and relative humidity at different geo-potential heights and pressures. In this work, the above…
Retrieval of characteristic parameters for water vapour transmittance in the development of ground based Sun-Sky radiometric measurements of columnar…
2014
Abstract. Sun–sky radiometers are instruments created for aerosol study, but they can measure in the water vapour absorption band allowing the estimation of columnar water vapour in clear sky simultaneously with aerosol characteristics, with high temporal resolution. A new methodology is presented for estimating calibration parameters (i.e. characteristic parameters of the atmospheric transmittance and solar calibration constant) directly from the sun–sky radiometer measurements. The methodology is based on the hypothesis that characteristic parameters of the atmospheric transmittance are dependent on vertical profiles of pressure, temperature and moisture occurring at each site of measurem…
Introducing Thermal Inertia for Monitoring Snowmelt Processes With Remote Sensing
2019
Thermal inertia has been successfully used in remote sensing applications that span from geology, geomorphology to hydrology. In this paper, we propose the use of thermal inertia for describing snow dynamics. Two different formulations of thermal inertia were tested using experimental and simulated data related to snowpack dynamics. Experimental data were acquired between 2012 and 2017 from an automatic weather station located in the western Italian Alps at 2,160 m. Simulations were obtained using the one‐dimensional multilayer Crocus model. Results provided evidences that snowmelt phases can be recognized, and average snowpack density can be estimated reasonably well from thermal inertia o…
Física de l'atmòsfera: Lliçó 5. Equacions de moviment
2012
Aquesta lliçó forma part del curs de Física de l'Atmosfera del segon curs del Grau en Física. El tema desenvolupa les equacions de la dinàmica atmosfèrica (Navier-Stokes) i estableix les aproximacions bàsiques (aproximacions geostròfica, hidrostàtica i equacions de pronòstic)
Sun-induced chlorophyll fluorescence II: Review of passive measurement setups, protocols, and their application at the leaf to canopy level
2019
Imaging and non-imaging spectroscopy employed in the field and from aircraft is frequently used to assess biochemical, structural, and functional plant traits, as well as their dynamics in an environmental matrix. With the increasing availability of high-resolution spectroradiometers, it has become feasible to measure fine spectral features, such as those needed to estimate sun-induced chlorophyll fluorescence (F), which is a signal related to the photosynthetic process of plants. The measurement of F requires highly accurate and precise radiance measurements in combination with very sophisticated measurement protocols. Additionally, because F has a highly dynamic nature (compared with othe…
The rapid atmospheric monitoring system of the Pierre Auger Observatory
2012
The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 1017 eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shor…
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
2009
Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ ∝ P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ∼ 10% seasonal modulation and ∼ 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is val…
Sentire lo spazio. L’architettura tra arte, natura ed esperienza estetica
2014
Con i movimenti ecologisti degli anni Settanta la tematica ambientale ha acquistato nuova centralità nel dibattito artistico, architettonico e filosofico. Tuttavia quando si affronta il tema dell’ambiente e del paesaggio, la prospettiva è prevalentemente ecologica e l’approccio di tipo scientifico. Raramente si tiene in considerazione che sia lo spazio naturale sia quello edificato sono soprattutto spazi percepiti e che le qualità estetiche dei luoghi non sono accessorie rispetto ai fattori tossicologici. La riflessione sviluppatasi in ambito architettonico, pur orientandosi verso la tutela dell’ambiente e l’armonica integrazione tra aree edificate e aree naturali, considera la bellezza un …
DesignArt. Ibridazioni creative tra arte e oggetti d’uso
2016
Oggi il mondo dell’arte si apre a un’ibridizzazione di forme e generi. La bellezza e la creatività, categorie fondamentali dell’arte secondo la tradizione idealistica e romantica, trovano nella vita quotidiana nuovi territori da colonizzare. In questo panorama di esteticità diffusa un fenomeno acquista particolare interesse: la DesignArt. La DesignArt costituisce un’intersezione tra due ambiti della creatività storicamente volti l’uno a progettare per l’industria oggetti seriali, utili ed esteticamente gradevoli, l’altro a ideare opere uniche e belle, ma senza scopo. Il luogo precipuo della DesignArt è l’ambiente vissuto, dove contemplazione e consumo si intrecciano in un’esperienza sineste…