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Literatura científica selecionada sobre o tema "Surface brightness temperature"

Autor: Grafiati

Publicado: 15 de março de 2025

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Artigos de revistas sobre o assunto "Surface brightness temperature"

Yin, Chuan, Ming Zhang e Yaming Bo. "Multilayer Brightness Temperature Tracing Method for Rough Surface Scene Simulation in Passive Millimeter-Wave Imaging". International Journal of Antennas and Propagation 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/6763182.

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Simulation in passive millimeter-wave (MMW) imaging of rough surfaces is an indispensable step in the simulation in passive radiation imaging, especially for the rough surfaces of different roughness surfaces. However, little attention has been paid to the simulation of rough surface; based on the existing model of brightness temperature tracing described in previous work, diffused reflection of the rough surface is taken into account in the improved model which is presented in this paper. In the paper, the brightness temperature tracing model of different roughness surfaces has been established. Then, we present a method called multilayer brightness temperature tracing (MBTT) method to obtain the radiation brightness temperature of rough surface. Hence, the discrimination of brightness temperature tracing method is enhanced.

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Shi, Jiu Xi, Jin Song Deng e Xiao Ming Wang. "Characteristic Analysis of Rural Environment Temperature Field". Advanced Materials Research 807-809 (setembro de 2013): 14–19. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.14.

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Taking villages in the northern plain of Shaoxing County Zhejiang Province as the research object and by using heat transfer model and remote sensing image analysis method and taking advantage of surface temperature information varying in different areas recorded by ETM thermal infrared band and through selection of special endmember, we realize the separation of background and ambient superposed brightness temperature and establish statistical model on change of superimposed environmental brightness temperature based on distance and analyze characteristics of rural environment temperature field according to the features of heat exchange type. Study shows that endmember brightness temperatures of different surface features in the study area are respectively as follows: hard surface is 304.663K, water body is 297.851K, grassland is 298.966K, woodland is 298.827K; superimposed environmental temperature in village area is about 1.737K. Environment superposed brightness temperature and distance function are tools to describe the temperature field, predicting pixel brightness temperature by using the heat transfer model is more accurate than using linear spectrum mixed model.

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Holbach, Heather M., Eric W. Uhlhorn e Mark A. Bourassa. "Off-Nadir SFMR Brightness Temperature Measurements in High-Wind Conditions". Journal of Atmospheric and Oceanic Technology 35, n.º 9 (setembro de 2018): 1865–79. http://dx.doi.org/10.1175/jtech-d-18-0005.1.

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AbstractWind and wave-breaking directions are investigated as potential sources of an asymmetry identified in off-nadir remotely sensed measurements of ocean surface brightness temperatures obtained by the Stepped Frequency Microwave Radiometer (SFMR) in high-wind conditions, including in tropical cyclones. Surface wind speed, which dynamically couples the atmosphere and ocean, can be inferred from SFMR ocean surface brightness temperature measurements using a radiative transfer model and an inversion algorithm. The accuracy of the ocean surface brightness temperature to wind speed calibration relies on accurate knowledge of the surface variables that are influencing the ocean surface brightness temperature. Previous studies have identified wind direction signals in horizontally polarized radiometer measurements in low to moderate (0–20 m s−1) wind conditions over a wide range of incidence angles. This study finds that the azimuthal asymmetry in the off-nadir SFMR brightness temperature measurements is also likely a function of wind direction and extends the results of these previous studies to high-wind conditions. The off-nadir measurements from the SFMR provide critical data for improving the understanding of the relationships between brightness temperature, surface wave–breaking direction, and surface wind vectors at various incidence angles, which is extremely useful for the development of geophysical model functions for instruments like the Hurricane Imaging Radiometer (HIRAD).

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Yang, Xiao Feng, e Xing Ping Wen. "Evaluation of Land Surface Temperature Retrieved from MODIS Data". Advanced Materials Research 785-786 (setembro de 2013): 1333–36. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.1333.

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Land surface temperature (LST) is important factor in global climate change studies, radiation budgets estimating, city heat and others. In this paper, land surface temperature of Guangzhou metropolis was retrieved from two MODIS imageries obtained at night and during the day respectively. Firstly, pixel values were calibrated to spectral radiances according to parameters from header files. Then, the brightness temperature was calculated using Planck function. Finally, The brightness temperature retrieval maps were projected and output. Comparing two brightness temperature retrieval maps, it is concluded that the brightness temperature retrieval are more accurate at night than during the day. Comparing the profile line of brightness temperature from north to south, the brightness temperature increases from north to south. Temperature different from north to south is larger at night than during the day. The average temperature nears 18°C at night and the average temperature nears 26°C during the day, which is consistent with the surface temperature observed by automatic weather stations.

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Winebrenner, Dale P., Eric J. Steig e David P. Schneider. "Temporal co-variation of surface and microwave brightness temperatures in Antarctica, with implications for the observation of surface temperature variability using satellite data". Annals of Glaciology 39 (2004): 346–50. http://dx.doi.org/10.3189/172756404781813952.

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AbstractSatellite observations of microwave emission are a key resource for estimating surface temperatures in Antarctica. Use of these data to examine climate variability, however, relies on the assumption of constancy through time in the relationship between surface temperatures and the proxy brightness temperatures. Thus we are motivated to study the physical relationship between surface and brightness temperature time series, and to seek indicators of possible temporal variability in that relationship. Here we report an initial study using near-surface temperatures from the Byrd Station automated weather station in West Antarctica and 37 GHz, vertically polarized brightness temperatures from the Scanning Multichannel Microwave Radiometer. We begin with the simplest model of the relevant thermal and microwave physics and derive a convolution expression that relates surface and brightness temperatures. The convolution kernel depends on firn thermal diffusivity and the microwave extinction coefficient in a particularly simple way: solely through a single characteristic time-scale. For the Byrd data, we find that the (fractional variation in) observed brightness temperatures can be reproduced by our model in considerable detail, on scales from interannual down to a few days. The time-scale is tightly constrained by minimization of the discrepancy between observed and simulated time series, and the optimized value agrees closely with that derived from independent estimates of firn thermal and microwave parameters. We find no evidence thus far of temporal variability in the relation between surface and brightness temperatures, though investigation across a wider domain in space and time is needed before such variability can be ruled out.

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Sherjal, I., e M. Fily. "Temporal variations of microwave brightness temperatures over Antarctica". Annals of Glaciology 20 (1994): 19–25. http://dx.doi.org/10.3189/1994aog20-1-19-25.

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Passive microwave brightness temperatures from the Special Sensor Microwave Imager (SSMI) are studied together with surface air temperatures from two Automatic Weather Stations (AWS) for the year 1989. One station is located on the East Antarctic plateau (Dome C) and the other on the Ross lee Shelf (Lettau).The satellite data for frequencies 19, 22 and 37 GHz with vertical polarization,centered on the two AWS stations, are studied. A simple thermodynamic model and asimple radiative-transfer model, that takes into account the snow temperature profile and assumes a constant annual emissivity, are proposed. The combination of these two models enables us to compute extinction coefficients, penetration depths and toretrieve the measured brightness temperature variations from the AWS surface temperatures. Afterwards, this model is reversed in order to retrieve the snow-surface temperatures from the satellite data. Results are promising but strong approximationsand a priori knowledge of the extinction coefficient are still needed at this point.

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Sherjal, I., e M. Fily. "Temporal variations of microwave brightness temperatures over Antarctica". Annals of Glaciology 20 (1994): 19–25. http://dx.doi.org/10.1017/s0260305500016177.

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Stephen, H., S. Ahmad e T. C. Piechota. "Land Surface Brightness Temperature Modeling Using Solar Insolation". IEEE Transactions on Geoscience and Remote Sensing 48, n.º 1 (janeiro de 2010): 491–98. http://dx.doi.org/10.1109/tgrs.2009.2026893.

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Gaustad, John E. "Temperature and brightness variations on Betelgeuse". Symposium - International Astronomical Union 118 (1986): 449–50. http://dx.doi.org/10.1017/s0074180900151885.

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Changes in Ti0 band strengths correlate well with the brightness changes of α Orionis, thus supporting the hypothesis of Schwarzschild that the irregular luminosity variations of red giants are due to temperature changes in a few extremely large convective elements on their surface.

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Chen, Xiuzhi, Yongxian Su, Yong Li, Liusheng Han, Jishan Liao e Shenbin Yang. "Retrieving China’s surface soil moisture and land surface temperature using AMSR-E brightness temperatures". Remote Sensing Letters 5, n.º 7 (3 de julho de 2014): 662–71. http://dx.doi.org/10.1080/2150704x.2014.960610.

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Mais fontes

Teses / dissertações sobre o assunto "Surface brightness temperature"

McAtee, Brendon Kynnie. "Surface-atmosphere interactions in the thermal infrared (8 - 14um)". Thesis, Curtin University, 2003. http://hdl.handle.net/20.500.11937/408.

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Remote sensing of land surface temperature (LST) is a complex task. From a satellite-based perspective the radiative properties of the land surface and the atmosphere are inextricably linked. Knowledge of both is required if one is to accurately measure the temperature of the land surface from a space-borne platform. In practice, most satellite-based sensors designed to measure LST over the surface of the Earth are polar orbiting. They scan swaths of the order of 2000 km, utilizing zenith angles of observation of up to 60°. As such, satellite viewing geometry is important when comparing estimates of LST between different overpasses of the same point on the Earth's surface. In the case of the atmosphere, the optical path length through which the surfaceleaving radiance propagates increases with increasing zenith angle of observation. A longer optical path may in turn alter the relative contributions which molecular absorption and emission processes make to the radiance measured at the satellite sensor. A means of estimating the magnitudes of these radiative components in relation to the viewing geometry of the satellite needs to be developed if their impacts on the at-sensor radiance are to be accurately accounted for. The problem of accurately describing radiative transfer between the surface and the satellite sensor is further complicated by the fact that the surface-leaving radiance itself may also vary with sensor viewing geometry. Physical properties of the surface such as emissivity are known to vary as the zenith angle of observation changes. The proportions of sunlit and shaded areas with the field-of-view of the sensor may also change with viewing geometry depending on the type of cover (eg vegetation), further impacting the surface emissivity.Investigation of the change in surface-leaving radiance as the zenith angle of observation varies is then also important in developing a better understanding of the radiative interaction between the land surface and the atmosphere. The work in this study investigates the atmospheric impacts using surface brightness temperature measurements from the ATSR-2 satellite sensor in combination with atmospheric profile data from radiosondes and estimates of the downwelling sky radiance made by a ground-based radiometer. A line-by-line radiative transfer model is used to model the angular impacts of the atmosphere upon the surfaceleaving radiance. Results from the modelling work show that if the magnitude of the upwelling and downwelling sky radiance and atmospheric transmittance are accurately known then the surface-emitted radiance and hence the LST may be retrieved with negligible error. Guided by the outcomes of the modelling work an atmospheric correction term is derived which accounts for absorption and emission by the atmosphere, and is based on the viewing geometry of the satellite sensor and atmospheric properties characteristic of a semi-arid field site near Alice Springs in the Northern Territory (Central Australia). Ground-based angular measurements of surface brightness temperature made by a scanning, self calibrating radiometer situated at this field site are then used to investigate how the surface-leaving radiance varies over a range of zenith angles comparable to that of the ATSR-2 satellite sensor.Well defined cycles in the angular dependence of surface brightness temperature were observed on both diumal and seasonal timescales in these data. The observed cycles in surface brightness temperature are explained in terms of the interaction between the downwelling sky radiance and the angular dependence of the surface emissivity. The angular surface brightness temperature and surface emissivity information is then applied to derive an LST estimate of high accuracy (approx. 1 K at night and 1-2 K during the day), suitable for the validation of satellite-derived LST measurements. Finally, the atmospheric and land surface components of this work are combined to describe surface-atmosphere interaction at the field site. Algorithms are derived for the satellite retrieval of LST for the nadir and forward viewing geometries of the ATSR-2 sensor, based upon the cycles in the angular dependence of surface brightness temperature observed in situ and the atmospheric correction term developed from the modelling of radiative transfer in the atmosphere. A qualitative assessment of the performance of these algorithms indicates they may obtain comparable accuracy to existing dual angle algorithms (approx. 1.5 K) in the ideal case and an accuracy of 3-4 K in practice, which is limited by knowledge of atmospheric properties (eg downwelling sky radiance and atmospheric transmittance), and the surface emissivity. There are, however, strong prospects of enhanced performance given better estimates of these physical quantities, and if coefficients within the retrieval algorithms are determined over a wider range of observation zenith angles in the future.

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McAtee, Brendon Kynnie. "Surface-atmosphere interactions in the thermal infrared (8 - 14um)". Curtin University of Technology, Department of Applied Physics, 2003. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=14481.

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Remote sensing of land surface temperature (LST) is a complex task. From a satellite-based perspective the radiative properties of the land surface and the atmosphere are inextricably linked. Knowledge of both is required if one is to accurately measure the temperature of the land surface from a space-borne platform. In practice, most satellite-based sensors designed to measure LST over the surface of the Earth are polar orbiting. They scan swaths of the order of 2000 km, utilizing zenith angles of observation of up to 60°. As such, satellite viewing geometry is important when comparing estimates of LST between different overpasses of the same point on the Earth's surface. In the case of the atmosphere, the optical path length through which the surfaceleaving radiance propagates increases with increasing zenith angle of observation. A longer optical path may in turn alter the relative contributions which molecular absorption and emission processes make to the radiance measured at the satellite sensor. A means of estimating the magnitudes of these radiative components in relation to the viewing geometry of the satellite needs to be developed if their impacts on the at-sensor radiance are to be accurately accounted for. The problem of accurately describing radiative transfer between the surface and the satellite sensor is further complicated by the fact that the surface-leaving radiance itself may also vary with sensor viewing geometry. Physical properties of the surface such as emissivity are known to vary as the zenith angle of observation changes. The proportions of sunlit and shaded areas with the field-of-view of the sensor may also change with viewing geometry depending on the type of cover (eg vegetation), further impacting the surface emissivity.
Investigation of the change in surface-leaving radiance as the zenith angle of observation varies is then also important in developing a better understanding of the radiative interaction between the land surface and the atmosphere. The work in this study investigates the atmospheric impacts using surface brightness temperature measurements from the ATSR-2 satellite sensor in combination with atmospheric profile data from radiosondes and estimates of the downwelling sky radiance made by a ground-based radiometer. A line-by-line radiative transfer model is used to model the angular impacts of the atmosphere upon the surfaceleaving radiance. Results from the modelling work show that if the magnitude of the upwelling and downwelling sky radiance and atmospheric transmittance are accurately known then the surface-emitted radiance and hence the LST may be retrieved with negligible error. Guided by the outcomes of the modelling work an atmospheric correction term is derived which accounts for absorption and emission by the atmosphere, and is based on the viewing geometry of the satellite sensor and atmospheric properties characteristic of a semi-arid field site near Alice Springs in the Northern Territory (Central Australia). Ground-based angular measurements of surface brightness temperature made by a scanning, self calibrating radiometer situated at this field site are then used to investigate how the surface-leaving radiance varies over a range of zenith angles comparable to that of the ATSR-2 satellite sensor.
Well defined cycles in the angular dependence of surface brightness temperature were observed on both diumal and seasonal timescales in these data. The observed cycles in surface brightness temperature are explained in terms of the interaction between the downwelling sky radiance and the angular dependence of the surface emissivity. The angular surface brightness temperature and surface emissivity information is then applied to derive an LST estimate of high accuracy (approx. 1 K at night and 1-2 K during the day), suitable for the validation of satellite-derived LST measurements. Finally, the atmospheric and land surface components of this work are combined to describe surface-atmosphere interaction at the field site. Algorithms are derived for the satellite retrieval of LST for the nadir and forward viewing geometries of the ATSR-2 sensor, based upon the cycles in the angular dependence of surface brightness temperature observed in situ and the atmospheric correction term developed from the modelling of radiative transfer in the atmosphere. A qualitative assessment of the performance of these algorithms indicates they may obtain comparable accuracy to existing dual angle algorithms (approx. 1.5 K) in the ideal case and an accuracy of 3-4 K in practice, which is limited by knowledge of atmospheric properties (eg downwelling sky radiance and atmospheric transmittance), and the surface emissivity. There are, however, strong prospects of enhanced performance given better estimates of these physical quantities, and if coefficients within the retrieval algorithms are determined over a wider range of observation zenith angles in the future.

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Zhang, Shuting. "Angular effects of surface brightness temperature observed from Sentinel-3A/SLSTR data". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAD055.

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Ce travail de thèse utilise les données TIR de SLSTR comme source principale pour extraire la température de brillance de la surface (SBT) en appliquant l’algorithme split-window, afin d’analyser l’effet angulaire sur la SBT. En se basant sur une base de données de simulation, une méthode d’extraction de la SBT a été développée et appliquée aux observations à double angle de SLSTR. L’étude a ensuite examiné l’amplitude et les caractéristiques des différences de SBT entre les vues nadir et obliques, en tenant compte de facteurs tels que l’occupation du sol /la couverture terrestre, la saison, la latitude et le climat. Enfin, l’outil GeoDetector a été utilisé pour effectuer une analyse d’attribution des effets angulaires sur la SBT
This study adopts SLSTR TIR data as the main data source and retrieves surface brightness temperature using split-window algorithm to analyze the angular effect of surface brightness temperature (SBT). Based on the simulation database, SBT retrieval method is developed and applied to SLSTR dual-angle SBT extraction. Then the magnitude and characteristics of SBT differences between nadir and oblique views were observed, considering factors such as land use/land cover, season, latitude and climate. Finally, GeoDetector tool was used to perform attribution analysis of SBT angular effects

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Van, den Bergh F., Wyk MA Van, Wyk BJ Van e G. Udahemuka. "A comparison of data-driven and model-driven approaches to brightness temperature diurnal cycle interpolation". SAIEE Africa Research Journal, 2007. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001082.

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This paper presents two new schemes for interpolating missing samples in satellite diurnal temperature cycles (DTCs). The first scheme, referred to here as the cosine model, is an improvement of the model proposed in [2] and combines a cosine and exponential function for modelling the DTC. The second scheme uses the notion of a Reproducing Kernel Hilbert Space (RKHS) interpolator [1] for interpolating the missing samples. The application of RKHS interpolators to the DTC interpolation problem is novel. Results obtained by means of computer experiments are presented.

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Hu, Tian. "Thermal Directionality Study and Application of Thermal Radiation to Drought Monitoring". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/392051.

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Remote sensing (RS), with its large spatial coverage and easily accessible observations, has attracted a lot of attention in recent years. Thermal infrared (TIR) RS, collecting radiation between 3.75 and 12.5 μm in the electromagnetic spectrum, is one of the major parts of RS. TIR RS is widely used in various fields, including evapotranspiration (ET), global climate change, hydrological cycle, vegetation monitoring and urban climate given the important role TIR radiation plays in surface energy and water balance. TIR radiation is closely related to land surface temperature (LST) and land surface emissivity (LSE). Angular variation is an important characteristic of LSE, which could influence the subsequent estimation of surface upwelling longwave radiation (SULR) and LST. In this study, a look-up table (LUT) of directional emissivities was built from the MYD21A product. The compiled LUT was then applied to SULR and LST estimation by considering the angular variation of LSE. The results showed that the influence of LSE angular variation on SULR estimation was not pronounced. Whereas, the influence on LST retrievals was > 0.5 K and the accuracy of the split-window (SW) was improved by > 1 K over barren surfaces after considering LSE directionality. LST is connected to ET through the surface energy balance equation, thereby reflecting vegetation water availability. In this study, applying TIR radiation in agricultural drought early warning was of interest. Based on the underlying principle that the rate of LST rise between 1.5 and 3.5 h after the sunrise is approximately linear and over vegetated surfaces occurs more rapidly under dry conditions as a consequence of stomatal control, the temperature rise index (TRI) was developed using the LST retrievals from the geostationary Multifunction Transport Satellite-2 (MTSAT-2) instrument and using the Himawairi-8 brightness temperatures (BT), respectively. The proposed TRI was evaluated by comparing with more commonly-used indices, including precipitation condition index (PCI), soil moisture condition index (SMCI) and vegetation condition index (VCI). In addition, the indices were also compared to annual wheat yield over large areas in the Australian Wheatbelt. The results showed that the TRI produced spatiotemporal dryness patterns that were very similar to those in soil moisture and precipitation, but with more detail due to its finer resolution. A time lag was found between TRI and observed vegetation condition, supporting the use of TRI in early warning. Among the compared drought indices, the TRI had the strongest and earliest correlation with wheat yield. The TRI calculated from LST and BT had close performances. It is concluded that this study provides insights into the basic theory study as well as practical applications of TIR RS, and adds value to the state-of-the-art studies in the field of TIR RS.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Dupont, Florent. "Télédétection micro-onde de surfaces enneigées en milieu arctique : étude des processus de surface de la calotte glaciaire Barnes, Nunavut, Canada". Thèse, Université de Sherbrooke, 2014. http://savoirs.usherbrooke.ca/handle/11143/5306.

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Résumé : La région de l'archipel canadien, située en Arctique, connaît actuellement d'importants changements climatiques, se traduisant notamment par une augmentation des températures, une réduction de l'étendue de la banquise marine et du couvert nival terrestre ou encore une perte de masse significative des calottes glaciaires disséminées sur les îles de l'archipel. Parmi ces calottes glaciaires, la calotte Barnes, située en Terre de Baffin, ne fait pas exception comme le montrent les observations satellitaires qui témoignent d'une importante perte de masse ainsi que d'une régression de ses marges, sur les dernières décennies. Bien que les calottes glaciaires de l'archipel canadien ne représentent que quelques dizaines de centimètres d'élévation potentielle du niveau des mers, leur perte de masse est une composante non négligeable de l'augmentation actuelle du niveau des mers. Les projections climatiques laissent à penser que cette contribution pourrait rester significative dans les décennies à venir. Cependant, afin d'estimer les évolutions futures de ces calottes glaciaires et leur impact sur le climat ou le niveau des mers, il est nécessaire de caractériser les processus physiques tels que les modifications du bilan de masse de surface. Cette connaissance est actuellement très limitée du fait notamment du sous-échantillonnage des régions arctiques en terme de stations météorologiques permanentes. Une autre particularité de certaines calottes de l'archipel canadien, et de la calotte Barnes en particulier, est de présenter un processus d'accumulation de type glace surimposée, ce phénomène étant à prendre en compte dans l'étude des processus de surface. Pour pallier au manque de données, l'approche retenue a été d'utiliser des données de télédétection, qui offrent l'avantage d'une couverture spatiale globale ainsi qu'une bonne répétitivité temporelle. En particulier les données acquises dans le domaine des micro-ondes passives sont d'un grand intérêt pour l'étude de surfaces enneigées. En complément de ces données, la modélisation du manteau neigeux, tant d'un point de vue des processus physiques que de l'émission électromagnétique permet d'avoir accès à une compréhension fine des processus de surface tels que l'accumulation de la neige, la fonte, les transferts d'énergie et de matière à la surface, etc. Ces différents termes sont regroupés sous la notion de bilan de masse de surface. L'ensemble du travail présenté dans ce manuscrit a donc consisté à développer des outils permettant d'améliorer la connaissance des processus de surface des calottes glaciaires du type de celles que l'on rencontre dans l'archipel canadien, l'ensemble du développement méthodologique ayant été réalisé sur la calotte Barnes à l'aide du schéma de surface SURFEX-CROCUS pour la modélisation physique et du modèle DMRT-ML pour la partie électromagnétique. Les résultats ont tout d'abord permis de mettre en évidence une augmentation significative de la durée de fonte de surface sur la calotte Barnes (augmentation de plus de 30% sur la période 1979-2010), mais aussi sur la calotte Penny, elle aussi située en Terre de Baffin et qui présente la même tendance (augmentation de l'ordre de 50% sur la même période). Ensuite, l'application d'une chaîne de modélisation physique contrainte par diverses données de télédétection a permis de modéliser de manière réaliste le bilan de masse de surface de la dernière décennie, qui est de +6,8 cm/an en moyenne sur la zone sommitale de la calotte, qui est une zone d'accumulation. Enfin, des tests de sensibilité climatique sur ce bilan de masse ont permis de mettre en évidence un seuil à partir duquel cette calotte voit disparaître sa zone d'accumulation. Les modélisations effectuées suggèrent que ce seuil a de fortes chances d'être atteint très prochainement, pour une augmentation de température moyenne inférieure à 1°C, ce qui aurait pour conséquence une accélération de la perte de masse de la calotte. // Abstract : Significant climate change is curently monitored in the Arctic, and especially in the region of the canadian arctic archipellago. This climate warming leads to recession of seaice extent and seasonnal snow cover, and also to large mass loss of the archipellago’s ice caps. One of the most southern ice cap, the Barnes Ice Cap, located on the Baffin Island, is no exception to significant mass loss and margins recession as satellite observations exhibited over the last decades. Despite the relative low sea level potential of the small ice caps located in the canadian arctic achipellago in regards to major ice sheets, Antarctica and Greenland, their contribution to the current sea level rise is significant. Climate projections show that this contribution could accelerate significant over the next decades. However, to estimate the future evolution of these ice caps and their impact on climate or sea level rise, a better characterisation of the surface processes such as the evolution of the surface mass balance is needed. This knowledge is currently very limited, mainly due to the sparse covering of automatic weather stations or in-situ measurements over the Arctic. Furthermore, several ice caps, among with the Barnes Ice Cap, present a superimposed ice accumulation area which particularities have to be taken into account in the surface processes studies. Given the lack of in-situ data, the approach choosen in this work is to use remote sensing data, that have the advantage to offer a good spatial and temporal coverage. In particular, passive microwave data are very suitable for snowy surfaces studies. To complement these data, physical and electromagnetic snowpack modeling provide a fine characterisation of surface processes such as snow accumulation. The whole work presented in this manuscript thus consisted in developping specific tools to improve the understanding of surface processes of small arctic ice caps. This methodological development was performed and applied on the Barnes Ice Cap using the surface scheme SURFEX-CROCUS and the electromagnetic model DMRT-ML. First results highlight a significant increase in surface melt duration over the past 3 decades on the Barnes Ice Cap (increase of more than 30% over 1979-2010 period). A similar trend is also monitored over the Penny Ice Cap, located in the south part of the Baffin Island (increase of more than 50% over the same period). Then, the surface mass balance over the last decade was modeled by using a physical based modeling chain constrained by remote sensing data. The results give a mean net accumulation of +6,8 cm y−1 on the summit area of the ice cap. Finaly, sensitivity tests, performed to investigate the climatic sensitivity of the surface mass balance, highlight a threshold effect that may lead to a complete disapearence of the accumulation area of the Barnes Ice Cap. With a temperature increase less than 1°C, modeling results suggest it is likely that the threshold will be reached rapidly leading to an increase in mass loss from the ice cap.

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Livros sobre o assunto "Surface brightness temperature"

D, Conner Mark, e United States. National Aeronautics and Space Administration., eds. Identification and classification of transient signatures in over-land SSM/I imagery. [Washington, DC: National Aeronautics and Space Administration, 1994.

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United States. National Aeronautics and Space Administration., ed. A well-calibrated ocean algorithm for special sensor microwave/imager. [Washington, DC: National Aeronautics and Space Administration, 1997.

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United States. National Aeronautics and Space Administration., ed. Deriving earth science products from SSM/I: Progress report for contract NASW-4714, August 1993 through January 1995. Santa Rosa, CA: Remote Sensing Systems, 1995.

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K, Moore Richard, e United States. National Aeronautics and Space Administration., eds. Correction of WindScat scatterometric measurements by combining with AMSR radiometric data. Lawrence, Kan: Radar Systems and Remote Sensing Laboratory, University of Kansas Center for Research, 1996.

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Radiometric correction of scatterometric wind measurements. Lawrence, KS: Radar Systems and Remote Sensing Laboratory, Dept. of Electrical Engineering and Computer Science, University of Kansas, 1995.

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Calculations of microwave brightness temperature of rough soil surfaces: Bare field. [Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 1985.

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Calculations of microwave brightness temperature of rough soil surfaces: Bare field. [Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 1985.

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Calculations of microwave brightness temperature of rough soil surfaces: Bare field. [Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 1985.

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Capítulos de livros sobre o assunto "Surface brightness temperature"

Grankov, Alexander G., e Alexander A. Milshin. "Influence of Horizontal Heat Transfer in the Atmosphere Boundary Layer on the Relationship Between the SOA’s Brightness Temperature and Surface Heat Fluxes: Modeling". In Microwave Radiation of the Ocean-Atmosphere, 73–84. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-21647-8_5.

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Vincent, Warwick F. "3. Sunlight and motion". In Lakes: A Very Short Introduction, 26–47. Oxford University Press, 2018. http://dx.doi.org/10.1093/actrade/9780198766735.003.0003.

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Water transparency powerfully indicates the state of health of a lake ecosystem. The water’s turbidity defines the physical habitat characteristics of lakes, strongly influencing their chemistry, biology, and ecosystem services. ‘Sunlight and motion’ explains the methods for measuring water transparency and how the penetration of sunlight into water declines with depth. The different colours, hues, and brightness levels of lakes are due to the materials dissolved and suspended within them. The layering of different temperature water in lakes is also described. This stratification varies greatly with the seasons. Mixing of the waters is mainly due to slow waves at and just below the surface as well as deeper currents.

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Valero, Mario M., Adam K. Kochanski e Craig B. Clements. "Remote characterization of fire behavior during the FireFlux II experiment". In Advances in Forest Fire Research 2022, 338–42. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_54.

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The FireFlux II field experiment was conducted on January 30th, 2013 in south-east Texas, USA, under high fire danger conditions. The experiment was designed to study the behavior of a head fire progressing through a flat, tall grass prairie, and it was informed by the use of a coupled fire-atmosphere model. Vegetation properties and fuel moisture were measured shortly before the experiment. Near-surface atmospheric conditions were monitored during the experiment using an elaborate meteorological instrumentation array. Fire behavior was observed through a combination of remote and in-situ sensors. Clements et al. (2019) presented the analysis of the experiment micrometeorology and in-situ fire behavior observations acquired using a thermocouple array. In this paper, we extend the study of fire behavior during the FireFlux II experiment with the analysis of remote sensing observations. Two thermal infrared and two visible cameras were deployed during the experiment. One thermal and one visible camera were mounted on a helicopter, whereas the other two cameras were installed on a 40-m-height tower next to the burn unit. The tower infrared camera covered a reduced area of interest coincident with the thermocouple array and it allowed monitoring the fire spread as well as measuring the spatially-resolved evolution of brightness temperature. Imagery collected from the helicopter allowed extending fire behavior measurements to the complete burn unit. While airborne IR footage was saturated and did not allow estimation of emitted radiant heat, its analysis allowed tracking fire progression through the plot and therefore estimating rate of spread and fire time of arrival. The existence of in-situ temperature observations provides an outstanding opportunity to validate remote sensing methodologies. In addition, the combination of remote observations with in-situ temperature measurements allows a comprehensive characterization of fire behavior, including spatially-resolved fire rate of spread and fire time of arrival, fire radiative power, Byramâ€™s fire line intensity, and air temperature during fire front passage. The current version of this paper presents preliminary results from this analysis. Such results demonstrate the usefulness of the selected datasets and the potential of the proposed methodology, encouraging further work. Possible applications of the resulting dataset include (i) the validation of existing fire behavior models that are able to predict any of the measured variables, (ii) the development of data-driven fire behavior models, and (iii) the investigation of the relative contribution of radiative and convective heat transfer mechanisms to fire spread.

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Ostlie, Dale A. "Measuring the Stars". In Astronomy: The Human Quest for Understanding, 589–637. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198825821.003.0015.

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Abstract Measuring the Stars begins the reader’s journey toward understand that stars are far more interesting than simply being dots distributed throughout the night sky. Armed with our knowledge of gravitation, light, atoms, and the production of light spectra, patterns in stellar characteristics emerge. Because only select wavelengths in the electromagnetic spectrum can reach Earth’s surface, and because of the distances light must travel to reach us, tremendous effort has gone into constructing telescopes that can gather as much light as possible from wherever we must go to obtain it. With information about the spectra of stars, paired with their brightnesses and distances, relationships between temperature, luminosity, and radii reveal themselves. The analysis of binary star orbits provides additional information about stellar masses. With the development of the Hertzsprung-Russell diagram, the stage was set for profound advances in our understanding of how stars work.

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Hoyt, Douglas V., e Kenneth H. Shatten. "Storms". In The Role of the Sun in Climate Change. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094138.003.0011.

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We now examine some attempts to link storm numbers and storm track locations to solar activity. The number of both tropical cyclones and thunderstorms has increased and decreased with time and location as a function of solar activity. In fact, an early correlation between the number of Indian cyclones and solar activity proved so startling it caused an explosion of related research. In the previous century, tropical cyclones were called hurricanes or typhoons. Today tropical cyclones refer only to the weaker tropical storms with sustained winds above 31 miles per hour. Here, tropical cyclones refer to the stronger storms like those in the previous century. Anywhere from 1 to about 30 hurricane-strength storms can form each year. Among other factors, formation of these storms requires oceanic water temperatures above 26 °C (79 °F). William Gray at Colorado State University has successfully predicted the number of Atlantic Ocean hurricanes each year. This number is a function of the equatorial wind direction, the sea-level air pressure in the Caribbean, the strength of the westerly winds near the top of the lower troposphere, the presence or absence of an El Niño current, and, particularly, the amount of rainfall in the Sahel in Africa. Earlier we noted that increased solar activity produces a corresponding increase in rainfall in some regions. Figure 6.4 indicates that increased rainfall in the Sahel is expected, so based on this expectation and Gray’s theory, hurricanes should increase in number. Higher solar activity and a higher solar irradiance can also be expected to increase the tropical ocean temperatures by a few tenths of a degree. These increased water temperatures tend to increase both the number of tropical cyclones and their intensity. Figure 7.1 illustrates the number of Atlantic Ocean hurricanes observed between 1962 and 1994 as a function of the sea-surface temperatures (SST). A sharp gradient exists in the number of storms produced between 23 and 25 °C. In some regions, even a small increase in SST can lead to sharp increases in the number of tropical cyclones. Changes in solar brightness on the 11-year time scale could be expected to cause a corresponding cycle in the number and strength of tropical cyclones.

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Trabalhos de conferências sobre o assunto "Surface brightness temperature"

"Land surface brightness temperature retrieved from Landsat data". In 21st International Congress on Modelling and Simulation (MODSIM2015). Modelling and Simulation Society of Australia and New Zealand, 2015. http://dx.doi.org/10.36334/modsim.2015.l11.li.

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Zhang, Xiaodong, Ji Zhou e Changming Yin. "Direct estimation of 1-KM land surface temperature from AMSR2 brightness temperature". In 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS). IEEE, 2017. http://dx.doi.org/10.1109/igarss.2017.8128087.

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Jiao, Zhong-Hu, Guangjian Yan, Tianxing Wang, Xihan Mu e Jing Zhao. "Modeling Surface Thermal Anisotropy Using Brightness Temperature over Complex Terrains". In IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2018. http://dx.doi.org/10.1109/igarss.2018.8518497.

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Chen, Fu, Yuanwen Zeng e Shuang Liang. "Relationship between Specific Surface Parameters and Brightness Temperature in Metropolitan Area". In The International Conference on Remote Sensing,Environment and Transportation Engineering. Paris, France: Atlantis Press, 2013. http://dx.doi.org/10.2991/rsete.2013.167.

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Zhou, Siyuan, Hongyu Xu, Xianchen Zhang e Weidong Hu. "Lunar surface radiation brightness temperature simulation for FY-4 lunar calibration". In 2021 14th UK-Europe-China Workshop on Millimetre-Waves and Terahertz Technologies (UCMMT). IEEE, 2021. http://dx.doi.org/10.1109/ucmmt53364.2021.9569894.

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Entekhabi, Dara, e Andrew F. Feldman. "Evaluating Brightness Temperature Information for Estimating Microwave Land Surface and Vegetation Properties". In IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2019. http://dx.doi.org/10.1109/igarss.2019.8900274.

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Freedman, A., D. McWatters e M. Spencer. "The Aquarius Scatterometer: An Active System for Measuring Surface Roughness for Sea-Surface Brightness Temperature Correction". In 2006 IEEE International Symposium on Geoscience and Remote Sensing. IEEE, 2006. http://dx.doi.org/10.1109/igarss.2006.436.

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Henocq, C., J. Boutin, F. Petitcolin, S. Arnault e P. Lattes. "Vertical variability of Sea Surface Salinity and influence on L-band brightness temperature". In 2007 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2007. http://dx.doi.org/10.1109/igarss.2007.4422966.

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Peng, Bin, Jiancheng Shi, Yonghui Lei, Tianjie Zhao e Dongyang Li. "Dual state-parameter estimation of land surface model through assimilating microwave brightness temperature". In SPIE Asia-Pacific Remote Sensing, editado por Thomas J. Jackson, Jing Ming Chen, Peng Gong e Shunlin Liang. SPIE, 2014. http://dx.doi.org/10.1117/12.2069608.

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Song, Chengyun, Li Jia e Massimo Menenti. "A method for retrieving high-resolution surface soil moisture by downscaling AMSR-E brightness temperature". In IGARSS 2012 - 2012 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2012. http://dx.doi.org/10.1109/igarss.2012.6351461.

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