Search results for "emissivity"

Error sources on the land surface temperature retrieved from thermal infrared single channel remote sensing data

2006

In this paper, a theoretical study complementary to others given in the literature about the errors committed on the land surface temperature retrieved from the radiative transfer equation in the thermal infrared region by remote sensing techniques has been analysed. For this purpose, the MODTRAN 3.5 code has been used in order to simulate different conditions and evaluate the influence of several parameters on the land surface temperature accuracy: atmospheric correction, noise of the sensor, land surface emissivity, aerosols and other gaseous absorbers, angular effects, wavelength uncertainty, full‐width half‐maximum of the sensor and band‐pass effects. The results show that the most impo…

Determination of the effective emissivity and temperature under vertical observation of a citrus orchard. Application to frost nowcasting

1988

Abstract In this work we use Becker's model for the determination of the effective temperature and emissivity under vertical observation of a citrus orchard. We apply this model to the particular case of a typically radiative night cooling (completely clear sky and calm wind) condition under which radiation frosts are normally produced which are damaging to the fruit and, consequently, to the Valencian economy. An attempt is made to establish a safety limit over which a frost cannot be produced. Ground and orange tree emissivity measurements were carried out by means of the box method. We were able to construct a hand-driven scanning system for the temperature measurement of the ground-oran…

Accuracy assessment of land surface temperature retrievals from MSG2-SEVIRI data

2011

The accuracy of the Land Surface Temperature (LST) product generated operationally by the EUMETSAT Land Surface Analysis Satellite Applications Facility (LSA SAF) from the data registered by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on board the geostationary METEOSAT Second Generation 2 (MSG2, Meteosat 9) satellite was assessed on two test sites in Eastern Spain: a homogeneous, fully vegetated rice field and a high-plain, homogeneous area of shrubland. The LSA SAF LSTs were compared with ground LST measurements in the conventional temperature-based (T-based) method. We also validated the LSA SAF LST product by using an alternative radiance-based (R-based) method, with grou…

Automatic classification-based generation of thermal infrared land surface emissivity maps using AATSR data over Europe

2012

The remote sensing measurement of land surface temperature from satellites provides a monitoring of this magnitude on a continuous and regular basis, which is a critical factor in many research fields such as weather forecasting, detection of forest fires or climate change studies, for instance. The main problem of measuring temperature from space is the need to correct for the effects of the atmosphere and the surface emissivity. In this work an automatic procedure based on the Vegetation Cover Method, combined with the GLOBCOVER land surface type classification, is proposed. The algorithm combines this land cover classification with remote sensing information on the vegetation cover fract…

Validation and comparison of two models based on the Mie theory to predict 8-14 µm emissivity spectra of mineral surfaces

2016

Land surface temperature derived from airborne hyperspectral scanner thermal infrared data

2006

Abstract The AHS (airborne hyperspectral scanner) instrument has 80 spectral bands covering the visible and near infrared (VNIR), short wave infrared (SWIR), mid-infrared (MIR), and thermal infrared (TIR) spectral range. The instrument is operated by Instituto Nacional de Tecnica Aerospacial (INTA) and it has been involved in several field campaigns since 2004. The main goal of this paper is to analyze the feasibility of retrieving land surface temperature from the 10 AHS thermal infrared bands, from 71 to 80, located in the region between 8 and 13 μm. For this purpose, three different methods have been considered: (i) the single-channel method, which uses only one thermal band; (ii) the sp…

Surface Emissivity Retrieval From Airborne Hyperspectral Scanner Data: Insights on Atmospheric Correction and Noise Removal

2012

Airborne multispectral imagers have been used in validation campaigns in order to acquire very high spatial resolution data as a benchmark for current or future satellite data. Imagery acquired with such sensors implies specific data processing in relation to view-angle-dependent atmospheric correction and removal or minimization of stripping-based noise. It is necessary to appropriately perform this processing in order to benefit from reference imageries of surface temperature (T) and emissivity (e) maps retrieved from thermal infrared data. In particular, e images generated from T/e separation algorithms show undesirable noise that jeopardizes their photointerpretation. This letter addres…

Plasma effects on neutrino-antineutrino synchrotron radiation in dense matter

2000

Abstract We consider plasma effects on ν ν synchroton radiation from ultrarelativistic, degenerate electrons in neutron stars with strong magnetic fields. Under typical conditions for such stars, a semiclassical calculation can be performed, in which electrons are considered to move along classical paths. We show that collective effects in the plasma lead to an essential enhancement (about three times) of the vector weak-current contributions to neutrino pair emissivity.

DISK REFLECTION SIGNATURES IN THE SPECTRUM OF THE BRIGHT Z-SOURCE GX 340+0

2008

We present the preliminary results of a 50 ks long XMM-Newton observation of the bright Z-source GX 340+0. In this Letter we focus on the study of a broad asymmetric emission line in the Fe K alpha energy band, whose shape is clearly resolved and compatible with a relativistically smeared profile arising from reflection on a hot accretion disk extending close to the central accreting neutron star. By combining temporal and spectral analysis, we are able to follow the evolution of the source along its Horizontal Branch. However, despite a significant change in the continuum emission and luminosity, the line profile does not show any strong correlated variation. This broad line is produced by…

Neutrino Pair Synchrotron Radiation from Relativistic Electrons in Strong Magnetic Fields

1995

The emissivity for the neutrino pair synchrotron radiation in strong magnetic fields has been calculated both analytically and numerically for high densities and moderate temperatures, as can be found in neutron stars. Under these conditions, the electrons are relativistic and degenerate. We give here our results in terms of an universal function of a single variable. For two different regimes of the electron gas we present a simplified calculation and compare our results to those of Kaminker et al. Agreement is found for the classical region, where many Landau levels contribute to the emissivity , but some differences arise in the quantum regime. One finds that the emissivity for neutrino …