Retrieval of land surface temperature and emissivity from satellite data: Physics, theoretical limitations and current methods     

Prasanjit Dash  Frank-M Göttsche  Folke-S Olesen  Herbert Fischer 《Journal of the Indian Society of Remote Sensing》2001,29(1-2):23-30

Remote sensing from satellites is the only means to obtain land surface temperature (LST) and emissivity on a larger scale. LST has many applications, e.g., in radiation budget experiments and global warming, and desertification studies. Over the last decades, substantial amount of research was dedicated towards extracting LST and emissivity from surface-leaving radiance and de-coupling the two from each other. This paper provides the physical basis, discusses theoretical limitations, and gives an overview of the current methods for space-borne passive sensors operating in the infrared range, e.g., NOAA-AVHRR, Meteosat, ERS-ATSR, TERRA-MODIS, and TERRA-ASTER. Atmospheric effects on estimated LST are described and atmospheric-correction using a radiative transfer model (RTM) is explained. The methods discussed are the single channel method, the split window techniques (SWTs), and the multi-angle method.  相似文献   

Heterogeneous strain of a phyllite as revealed by porphyroblast-matrix relationships     

N. . Olesen 《Journal of Structural Geology》1982,4(4):481-490

Garnet porphyroblasts in a homogeneous phyllite specimen from the central Norwegian Caledonides provide insight into the distribution and type of strain which followed the garnet growth. Matrix schistosity is traceable through the porphyroblasts in the form of inclusions which allow the measurement of two parameters: the flattening of the matrix schistosity around the porphyroblasts, and an angle of rotation of the porphyroblasts relative to the matrix schistosity. Both parameters vary considerably as studied in a large thin section cut parallel to mineral lineation and perpendicular to schistosity. Accepting some simplifications and assumptions, it seems necessary to consider the strain as composed of two components: a noncoaxial strain component of a simple-shear type, and an approximately coaxial strain component, both of which are heterogeneously developed on the scale of the thin section. The shear planes of the simple-shear-type strain are likely to lie parallel, or at a very small angle, to the matrix schistosity. The linear fabric of the phyllite seems to be a material expression of the coaxial strain component. The λ₁λ₂ plane of the finite strain ellipsoid most probably varies in orientation across the thin section and is only, by coincidence, parallel to the almost constantly oriented matrix schistosity.  相似文献   

The Mesozoic–Cenozoic structural framework of the Bay of Kiel area, western Baltic Sea     

Martin Bak Hansen  Holger Lykke-Andersen  Ali Dehghani  Dirk Gajewski  Christian Hübscher  Morten Olesen  Klaus Reicherter 《International Journal of Earth Sciences》2005,94(5-6):1070-1082

A dense grid of multichannel high-resolution seismic sections from the Bay of Kiel in the western Baltic Sea has been interpreted in order to reveal the Mesozoic and Cenozoic geological evolution of the northern part of the North German Basin. The overall geological evolution of the study area can be separated into four distinct periods. During the Triassic and the Early Jurassic, E–W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. The deposition ceased during the Middle Jurassic, when the entire area was uplifted as a result of the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic and Lower Jurassic strata. This event is marked by a clear angular unconformity on all the seismic sections. The region remained an area of non-deposition until the end of the Early Cretaceous, when the sedimentation resumed in the area. Throughout the Late Cretaceous the sedimentation took place under tectonic quiescence. Reactivated salt movement is observed at the Cretaceous Cenozoic transition as a result of the change from an extensional to compressional regional stress field. The vertical salt movement influenced the Cenozoic sedimentation and resulted in thin-skinned faulting.  相似文献   

Airborne geophysical prospecting for ultramafite associated talc, Altermark, northern Norway     

Tor Arne Karlsen  Odleiv Olesen 《Journal of Applied Geophysics》1996,35(4):215-236

Talc-rich rocks in Altermark occur as rims around magnetite bearing serpentinite lenses which are up to about 1 km wide. The content of magnetite in the serpentinite makes magnetic measurements possible as a method for talc-prospecting. In 1991 a helicopter-borne geophysical survey combined with geological and petrophysical mapping was carried out in the Altermark area. Several positive magnetic anomalies were detected. Positive magnetic anomalies with oval shapes, well defined boundaries and smooth anomaly curves were interpreted to be caused by serpentinite lenses. Laboratory measurements revealed susceptibilities for the serpentinites between 0.006−0.36 SI and a Q-value of approximately 0.3. Magnetic modelling of the Nakkan anomaly and subsequent drilling revealed that it was indeed a serpentinite body surrounded by talc rocks which was the cause of the anomaly. The shallowest part was located about 150 m below surface. The geophysical exploration led to the discovery of a talc-carbonate deposit with an anticipated in situ tonnage of more than 1 million tons. The present study consequently proved to be a classical case study where we were able to locate and establish the three-dimensional form of serpentinite bodies associated with talc deposits. We conclude that helicopter-borne geophysical surveying is an effective tool in the exploration of serpentinite cored talc bearing rocks in complex geological areas where exposures are poor or absent and accessibility difficult. The rough topography and dense vegetation in the Altermark area make this type of survey very cost effective.  相似文献   

Merging of Airborne Gravity and Gravity Derived from Satellite Altimetry: Test Cases Along the Coast of Greenland     

Olesen  A. V.  Andersen  O. B.  Tscherning  C. C. 《Studia Geophysica et Geodaetica》2002,46(3):387-394

The National Survey and Cadastre - Denmark (KMS) has for several years produced gravity anomaly maps over the oceans derived from satellite altimetry. During the last four years, KMS has also conducted airborne gravity surveys along the coast of Greenland dedicated to complement the existing onshore gravity coverage and fill in new data in the very-near coastal area, where altimetry data may contain gross errors. The airborne surveys extend from the coastline to approximately 100 km offshore, along 6000 km of coastline. An adequate merging of these different data sources is important for the use of gravity data especially, when computing geoid models in coastal regions.The presence of reliable marine gravity data for independent control offers an opportunity to study procedures for the merging of airborne and satellite data around Greenland. Two different merging techniques, both based on collocation, are investigated in this paper. Collocation offers a way of combining the individual airborne gravity observation with either the residual geoid observations derived from satellite altimetry or with gravity derived from these data using the inverse Stokes method implemented by Fast Fourier Transform (FFT).  相似文献   

Tree survey and allometric models for tiger bush in northern Senegal and comparison with tree parameters derived from high resolution satellite data     

Mads Olander Rasmussen  Frank-M. Göttsche  Doudou Diop  Cheikh Mbow  Folke-S. Olesen  Rasmus Fensholt  Inge Sandholt 《International Journal of Applied Earth Observation and Geoinformation》2011

A tree survey and an analysis of high resolution satellite data were performed to characterise the woody vegetation within a 10 × 10 km² area around a site located close to the town of Dahra in the semi-arid northern part of Senegal. The surveyed parameters were tree species, height, tree crown radius, and diameter at breast height (DBH), for which allometric models were determined. An object-based classification method was used to determine tree crown cover (TCC) from Quickbird data. The average TCC from the tree survey and the respective TCC from remote sensing were both about 3.0%. For areas beyond the surveyed areas TCC varied between 3.0% and 4.5%. Furthermore, an empirical correction factor for tree clumping was obtained, which considerably improved the estimated number of trees and the estimated average tree crown area and radius. An allometric model linking TCC to tree stem crosssectional area (CSA) was developed, which allows to estimate tree biomass from remote sensing. The allometric models for the three main tree species found performed well and had r²-values of about 0.7–0.8.  相似文献   

Accumulation of Copper and Zinc in Danish Agricultural Soils in Intensive Pig Production Areas     

Ilse Gräber  Jørgen F. Hansen  Svend E. Olesen  Jens Petersen  Hans S. Østergaard  Lars Krogh 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):15-22

Geografisk Tidsskrift, Danish Journal of Geography 105(2):15–22, 2005

The change of Cu and Zn concentrations in Danish agricultural soils was studied in areas with intensive pig production. Cu and Zn are found in pig manure as the metals are added to pig feed as growth promoters. The changes in concentrations of total and 0.02 MEDTA extractable Cu and Zn in soils from 1986 to 1998 were determined from samples taken at two depths (0–25 cm and 25–50 cm) from 73 sites. Pig manure and mineral fertilizer was added to 60 sites whereas fertilizer only was used on 13 sites. During the survey period soil Cu concentrations increased in both depths but mostly in the sites where pig manure was added. Furthermore, the results indicated that some plant-available Cu and Zn were transported from the topsoil to the subsoil. No significant change in soil Zn concentration was found although a slight reduction was observed. Comparing soil metal concentrations observed in 1998 to the total pig manure application in a 12-year period, it was observed that application of manure caused an accumulation of Cu and of Zn in the upper 50 cm soil. The accumulation rates correspond to the Cu and Zn concentrations in the pig manure.  相似文献   

Airborne Gravimetry Survey for the Marine Area of the United Arab Emirates     

Rene Forsbergbi  Arne Vestergaard Olesen  Adel Alshamsi  Arne Gidskehaug  Sahrum Ses  Majid Kadir 《Marine Geodesy》2013,36(3):221-232

The Military Survey Department (MSD) of the United Arab Emirates (UAE) undertook an airborne gravity survey project for the marine area of the country in 2009, especially to strengthen the marine and coastal geoid in the near-shore regions. For the airborne gravity survey, 5 km spacing coast-parallel flight lines were planned and surveyed. These lines were supplemented by cross-lines in order to assess the quality of the airborne gravity surveys. The flight lines were extended 10 km, spacing lines further offshore. A Beech King Air 350 aircraft was used for the surveys, collecting data at a typical flight speed of 170 knots and a typical flight elevation of 900–1500 m, depending on weather conditions and topography. Gravity was measured with a ZLS-modified LaCoste and Romberg gravimeter (S-99), augmented with a Honeywell strap-down inertial navigation system unit. The estimated accuracy for the airborne gravity data is better than 2.0 mGal r.m.s., as judged from the airborne track crossovers. The new airborne gravimetry data changed the UAE coastal geoid by up to 30 cm in some regions, highlighting the importance of airborne gravity coastal surveys.  相似文献   

Effect of warming and nitrogen addition on evapotranspiration and water use efficiency in a wheat-soybean/fallow rotation from 2010 to 2014   总被引：1，自引：0，他引：1  

Liting Liu  Chunsheng Hu  Jørgen E. Olesen  Zhaoqiang Ju  Xiying Zhang 《Climatic change》2016,139(3-4):565-578

  相似文献   

A framework for testing the ability of models to project climate change and its impacts   总被引：1，自引：0，他引：1  

J. C. Refsgaard  H. Madsen  V. Andréassian  K. Arnbjerg-Nielsen  T. A. Davidson  M. Drews  D. P. Hamilton  E. Jeppesen  E. Kjellström  J. E. Olesen  T. O. Sonnenborg  D. Trolle  P. Willems  J. H. Christensen 《Climatic change》2014,122(1-2):271-282

Models used for climate change impact projections are typically not tested for simulation beyond current climate conditions. Since we have no data truly reflecting future conditions, a key challenge in this respect is to rigorously test models using proxies of future conditions. This paper presents a validation framework and guiding principles applicable across earth science disciplines for testing the capability of models to project future climate change and its impacts. Model test schemes comprising split-sample tests, differential split-sample tests and proxy site tests are discussed in relation to their application for projections by use of single models, ensemble modelling and space-time-substitution and in relation to use of different data from historical time series, paleo data and controlled experiments. We recommend that differential-split sample tests should be performed with best available proxy data in order to build further confidence in model projections.  相似文献