Search results for "Remote Sensing"

Joint Gaussian Processes for Biophysical Parameter Retrieval

2017

Solving inverse problems is central to geosciences and remote sensing. Radiative transfer models (RTMs) represent mathematically the physical laws which govern the phenomena in remote sensing applications (forward models). The numerical inversion of the RTM equations is a challenging and computationally demanding problem, and for this reason, often the application of a nonlinear statistical regression is preferred. In general, regression models predict the biophysical parameter of interest from the corresponding received radiance. However, this approach does not employ the physical information encoded in the RTMs. An alternative strategy, which attempts to include the physical knowledge, co…

Estimating crop primary productivity with Sentinel-2 and Landsat 8 using machine learning methods trained with radiative transfer simulations

2019

Abstract Satellite remote sensing has been widely used in the last decades for agricultural applications, both for assessing vegetation condition and for subsequent yield prediction. Existing remote sensing-based methods to estimate gross primary productivity (GPP), which is an important variable to indicate crop photosynthetic function and stress, typically rely on empirical or semi-empirical approaches, which tend to over-simplify photosynthetic mechanisms. In this work, we take advantage of all parallel developments in mechanistic photosynthesis modeling and satellite data availability for an advanced monitoring of crop productivity. In particular, we combine process-based modeling with …

Hyperspectral imaging of asteroids using an FPI-based sensor

2021

The compositions of asteroids are of interest for the planetary sciences, mining, and planetary defense. The main method for evaluating these compositions is reflectance spectroscopy. Spectroscopic measurements performed from Earth can not resolve how different materials are distributed on the asteroids, making flyby-- and rendezvous missions necessary for obtaining detailed information. Using the CubeSat platform could reduce the costs of these missions, but it also sets constraints on the payload mass and volume. One small and light instrument capable of producing spatially resolved spectral data is a hyperspectral imager based on the Fabry-Perot interferometer. We propose a method of cal…

Remote sensing and climate data as a key for understanding fasciolosis transmission in the Andes: review and update of an ongoing interdisciplinary p…

2006

Fasciolosis caused by Fasciola hepatica in various South American countries located on the slopes of the Andes has been recognized as an important public health problem. However, the importance of this zoonotic hepatic parasite was neglected until the last decade. Countries such as Peru and Bolivia are considered to be hyperendemic areas for human and animal fasciolosis, and other countries such as Chile, Ecuador, Colombia and Venezuela are also affected. At the beginning of the 1990s a multidisciplinary project was launched with the aim to shed light on the problems related to this parasitic disease in the Northern Bolivian Altiplano. A few years later, a geographic information system (GIS…

A mathematical study on effective wavenumber, an operative computation procedure, and its use with radiance-temperature relationships

2003

In this paper we study the existence of effective wavenumber for any sensor by means of simple mathematics. We implement a numeric algorithm, based on the developed mathematical background, into a computer program named 'srf2radi', which is freely available via anonymous File Transfer Protocol (FTP) at ftp://ftp.uv.es/pub/src/. The number of effective wavenumbers for each temperature and their accuracy are also computed and studied for NOAA-16 Advanced Very High Resolution Radiometer Version 3 (AVHRR/3) channel 4. These effective wavenumbers can be used to obtain radiance-temperature relationships with physical meaning for any sensor in user-defined temperature intervals.

Measurement and Conservation of Species and Habitat Biodiversity at Different Scales on Small Mediterranean Islands

2021

In this paper we discuss current methodologies for measuring biodiversity, analyse pros and cons at different scales, and finally propose distribution mapping as the most suitable method for measuring floristic biodiversity on small Mediterranean islands. These territories often host endangered flora and habitats, and have peculiarities that distinguish them from the mainland and the larger islands.

Cover Feature: Flow Photochemistry of Azosulfones: Application of “Sunflow” Reactors (ChemPhotoChem 10/2018)

2018

Activation radius of aerosol particles in cloud events - ground based and aircraft field measurements

1997

Novel leaf-level measurements of chlorophyll fluorescence for photosynthetic efficiency

2015

Solar induced chlorophyll fluorescence (SIF) from vegetation can now be obtained from satellites as well as ground-based field studies, at select wavelengths associated with atmospheric features. At the leaf level, full spectrum (650–800 nm) chlorophyll emissions (ChlF) can be measured using specialized instrumentation to support interpretation of these SIF observations. We found that ChlF spectra differ for leaf bottoms versus upper leaf surfaces, potentially affecting within-canopy radiative scattering. Our ChlF measurements for leaves of eight tree species (n≥125) obtained during fall 2013 senescence at the Duke Forest in North Carolina, USA and the 2014 growing season (n=72) at the USDA…

REMOTE SENSING ANALYSIS COUPLED TO FIELD MEASUREMENTS FOR THE EVALUATION OF METHANE EMISSIONS FROM A LANDFILL SITE: A CASE STUDY

2015

SUMMARY: the waste disposal in sanitary landfills generates landfill gas (LFG), mainly constituted by methane (CH4) and carbon dioxide (CO2), because of the anaerobic degradation of the organic matter contained in the disposed waste. It is worth mentioning that CH4 is recognized as one of the most important contributor to global warming and sanitary landfills for Municipal Solid Waste (MSW) have been found to be a significant source of CH4 generation and emission. The main aim of the present work was the evaluation of methane emissions from a Sicilian landfill site by coupling of direct field measurements and ground temperature data acquired through remote sensing techniques. It is worth me…