Navegando por Assunto "Radar nas geociências"

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Acesso aberto (Open Access)
A influência dos parâmetros biofísicos da vegetação de mangue em regeneração no retroespelhamento de imagens radarsat-2 multipolarizada na Amazônia, Brasil
(Universidade Federal do Pará, 2013-09-05) COUGO, Michele Ferreira; SILVA, Arnaldo de Queiroz da; http://lattes.cnpq.br/1682623730626187; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
The main goal of this work is to understand the relationship between backscattering (σ°, β° e γ) of a multipolarized Radarsat-2 Fine Beam band C image with biophysical parameters of mangrove vegetation in regeneration. The study site was the Bragança peninsula (northeast of Pará State) far from the Amazon River mouth about 380 km (southeast). 30 years ago it was built a highway causing disturbances in the hydrological regimes and vegetation death, then it was deforested and currently the natural regeneration is incipient. Field data was taken in 17 stands of 10 square meters and it was delimited and positioned with a DGPS (Differential Global Positioning System) and a total station. Structural characterization of the sampling units was made with the following field data: CBH (circumference at breast height), height and specie in 3090 specimen and then it were estimated values of DBH (diameter at breast height) and BA (basal area). A cluster analysis of the sample units has defined four groups of vegetation in different regeneration stages: pioneer stage, initial regeneration, intermediate regeneration and advanced regeneration. Fromard et al. (1998) equation was used to biomass estimation. It was used a SLC (Single Look Complex) multipolarized image (Radarsat-2) from June 11th, 2010. VIMAGE/Focus/PCI software was used to retrieve backscattering values of SAR (Synthetic Aperture Radar) image, using as reference the limits of the parcels. Statistical models of simple and multiple regressions were used in the analysis of the relationship between vegetation structure and backscattering values of the SAR image. Results shown that linear sigma backscattering with cross-polarization (VH) had the strongest relationship with all vegetation structure analyzed. Although the function of multiple linear regression with HH, VH and VV polarization got the best adjustments with the biophysical parameters mean height, DBH and Biomass (R2 values were respectively 0,81, 0,79 and 0,79). Backscattering values of the image with adjusted functions were used to generate maps of these three biophysical variables and it was coherence with field data, mainly mean height and DBH maps. Biomass map got a low amplitude variation suggesting saturation of the sign, in mangroves in regeneration, less than indicated in the literature to band C in homogeneous mangrove areas.
Acesso aberto (Open Access)
Metodologia de interpretação radargeológica: exemplo da sinéclise do Parnaíba e de seu embasamento
(Universidade Federal do Pará, 1995-09-29) LIMA, Mário Ivan Cardoso de; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
This thesis develops the Radargraphic Elements Sistematic method, unknown throughout the world, in the geologic interpretation with Side-Looking Radar (Radargeology), a technique of major relevante in the field of natural resources, considering that the 1990s are the Radar's decade. The Radargraphic Elements Sistematic (SER) method reveals in a sistematic form the methodological route adopted , be it trough the text, trough schematic figures, or in Side-Looking Radar (SLR), with the radargraphic elements (features), ordered in five different stages: Reading, Recognizing, Identifying, Analisys and Interpretation (stricto senso). The stage Reading seeks to understand the meaning of the image elements in the terrain, with the goal of understand their meaning ; the Recognizing stages seek to group them according to the texture and tone radargraphic, so as to obtain homogeneous radargraphic zones; Identification seeks to study the relief forms in such zones, with regard to top and pending, as well as the studying of the drainage patterns, dissection degree and erosion resistance ;and the Analysis establishes the spacial and temporal relation of the relief forms researched through linear, planar and tabular features. With such information in hand , the Interpretation stage itself is reach, in which is possible to define lithologies, rounded structures, unconformities, discontinuities, folds and their interrelations,with a view to executing the Radargeological Map.In effect, a model area was selected to serve a paradigm for the the different methodological stages. To apply the Radargraphic Elements Sistematic method, the region encompassed by Parnaíba Sineclyse and its embasement was selected, with an area of around 925 000 km2, involving mostly Maranhão e Piauí states, located in northeastern region of Brazil. Such an example seeks to emphasys the applicability of the remote sensing in sedimentar terrains and their metamorphic embasement, due to academic and economic importance involved.. To carry out this stage, 52 SLR images mosaics were utilized, scale, I: 250 000, GEMS, X band, resulting in the definition of 39 basic radargeologicals unities, with a temporal stratigraphy, and 19 regional strucutures and 30 local ones, of which more than half were unpublished. These results are expressed in an explanatory text with ilustrations, including a Radargological Map on the milionth scale , and a structural sketch on the scale of 1:2 000 000. The study reaches a favorable conclusion regarding the potentialities of SLR images in geological whose difficulties in defining the radargraphic elements (features) due mainly to extensive shadows, foreshortening , layover and paralaxe effects, will be overcome with the use of more sophisticated Radar Systems (digital mode, stereoscopy, multifrequency, differents angles of incidence,etc) , as is the case with SIR-C and RADARSAT. Finally, the study attests of the excelence of Radargraphic Elements Sistematic method considering the results achieve with the study of the Parnaíba Sineclyse and its embasement, such as : definition of radargeological units, which mantain a strict relation with the lithostratigraphic units already described in the literature; structural setting with the identification of almost 50 morphostructures of regional and local character , and a perfect correlation with aeromagnetic maps.
Acesso aberto (Open Access)
Morfodinâmica costeira e o uso da orla oceânica de Salinópolis (Nordeste do Pará)
(Universidade Federal do Pará, 2014-12-15) RANIERI, Leilanhe Almeida; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429
The morphodynamic aspects related to erosion or accretion of the coastline are some of the topics analyzed in the management of coastal zones being discussed around the world in order to monitor and protect these zones. This thesis aims to analyze the behavior of the coastal morphodynamics of the Salinópolis, relating to the use of ocean margin. The study area was compartmentalized into three sectors: Western (Corvina and Maçarico beaches), Center (Farol Velho beach) and Eastern (Atalaia beach). The methodology consisted of: (a) acquisition and processing of multi-temporal images (1988-2001-2013) of the Landsat 5 TM, 7 ETM and 8 OLI; (b) application of interviews/questionnaires with bathers, (c) acquisition of field data during the rainy season (April 26th, 27th and 28th, 2013) and less rainy (045.5) prevailed at these beaches, but with the occurrence of the the longshore bar and trough state (4.7 <Ω <5.5) in the western sector. The macrotidals in the study area showed maximum height of 5.3 m (Center Sector during the less rainy season) and a minimum of 4 m in the same sector during the rainy season. The longshore currents were more intense in the eastern sector (> 0.45 m / s) during the two seasons of the year. The wave heights were also higher in the eastern sector (maximum of 1.05 m during the flood tide in the less rainy season) and wave periods were shorter (<4.5 s) in the western sector. The mean grain size obtained from sediments collected on the beaches had more frequent scale between 2.6 to 2.8 phi, indicating the predominance of fine sand. The predominant degree of sorting of sediment was 0,2 to 0,5 phi (very well sorted and well sorted), and asymmetry was positive (0.10 to 0.30) and nearly symmetrical (-0.10 to 0.10). The degree of kurtosis ranged from very platykurtic (<0.67) to very leptokurtic (1.50 to 3.00). Sediment accretion events were observed of the rainy season to less rainy season. From 07/22/1988 to 08/28/2013 (25 years) also predominated accretion, where the average linear advancement of the coastline was 190.26 m. The average linear retreat obtained for the entire study area was -42.25 m. The eroding areas are point: currencies from the beaches of Corvina and Maçarico, and Farol Velho and Atalaia. Portable traps indicated a greater quantity of sediment transported longitudinally in the less rainy season (minimum 280 g/m3: flood, west sector; maximum 1098 g/m3: ebb, east sector). In the traps applied in the swash zone, the balance of sediment entering and leaving the beaches was lower in the center sector (minimum 80 g/m3: ebb, maximum 690 g/m3: flood; less rainy season). The coastal sediment movement is derived mainly from effect of the tides, which are oriented toward the direction of the ebb and flow of the estuary crossing the coast. The data indicate the longshore transport of sediment from the Atalaia island and Sampaio River to the west sector and the beaches margins.
Acesso aberto (Open Access)
Reconhecimento de ambientes costeiros a partir da análise de imagens do SAR R99 B, banda L
(Universidade Federal do Pará, 2007-11-01) GUALBERTO, Lílian Poliana Sousa; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252
In response to climatic conditions and imaging characteristics, Synthetic Aperture Radar (SAR) become an option to mapping and monitor tropical coastal zones. SAR R99 B, for their operational characteristics (high space resolution, incidence angle, polarization, wavelength) it presents a great potential for the recognition of tropical zone, as the coastal plain of Bragança. The analysis and interpretation of the images SAR R99 B were based on the basic elements of extraction of information of objects, area, or phenomena. To follow the evaluation of band L discriminatory capacity in the coastal atmospheres: 1) the salt marsh present tonal widths of medium to darkness due to the reflection to speculate and diffuse, the factors that influence the intensity of the return of the electromagnetic waves are the personal micro-relief, presence of water and the vegetation. Like this, the response of the interaction of the band L, in the polarization HH, with the marsh is characterized by dark tones and the limits of the fields with the marsh are defined better, that with the polarization VV; 2) only in the polarization VV was identified to the beach of Ajuruteua, that this acted by a blackened surface, that it corresponds to the response of the interaction of the band L with the intertidal zone; 3) the coastal dunes have the same orientation of screeching of SAR R99 B during the acquisition of the images (E-W), in other words, it forms a rectum angle with the illumination direction (N-S). Like this, the dunes are very well discriminated in the band L, in both polarizations; 4) the coastal plain was individualized better in the polarization VV, in relation to the polarization HH; 5) in both polarizations, the discrimination of the old beach ridges is favored by the double-bounce effect, that provides a larger shine of these bodies in relation to the growth of mangroves; 6) the distinction of the intertidal mangrove is due to the volumetric scattering and double-bounce mechanism. This condition peculiar of answers of the interaction of the microwaves with the dossal of the marsh is responsible for a very wrinkled texture and diamond of this unit geobotanical. This behavior is observed in both polarizations; 7) the supratidal mangrove presents a similar behavior that the intertidal mangrove, however the trees of that dossal are smaller and spaced, reducing the effect couple reflection. Consequently, there is a reduction of the rugosity; 8) in the deflorested swamp, the clay soil exposed, and the answer of the sign of that flat surface is characterized in the image by the very dark ash tones in the polarizations HH and VV; 9) the re-establishment of the flow of the tides, in some areas of the deflorested mangrove has been generating new environmental conditions, that they are revitalizing that mangrove. Like this, the answer to the interaction with the microwaves is different, if compared to the others, with wrinkled aspect with intermediate ash tones to the of the intertidal mangrove and supratidal. In terms of dispersion of the ash levels, the image in the polarization VV presents a variability of 25% larger than in HH. From way, attributing a larger capacity of identification of objectives in the polarization VV. The main parameters of the sensor that you/they influence the capacity of discrimination of the coastal atmospheres were the polarization and incidence angle. Like this, it was identified a larger number of objectives with the polarization VV. However, in the polarization HH the limits of the atmospheres were defined better. These results demonstrated that the polarizations are complemental in the answer of the objectives in the coastal plane.
Acesso aberto (Open Access)
Use of synthetic aperture radar for recognition of Coastal Geomorphological Features, land-use assessment and shoreline changes in Bragança coast, Pará, Northern Brazil
(2003-09) SOUZA FILHO, Pedro Walfir Martins e
Synthetic Aperture Radar (SAR) images are being used more extensively than ever before for geoscience applications in the moist tropics. In this investigation, a RADARSAT1-1 C-HH SAR image acquired in 1998 was used for coastal mapping and land-cover assessment in the Bragança area, in the northern Brazil. The airborne GEMS 1000 X-HH radar image acquired in 1972 during the RADAM Project was also used for evaluating coastal changes occurring over the last three decades. The research has confirmed the usefulness of RADARSAT-1 image for geomorphological mapping and land-cover assessment, particularly in macrotidal mangrove coasts. It was possible to map mangroves, salt marshes, chenier sand ridges, dunes, barrier-beach ridges, shallow water morphologies and different forms of land-use. Furthermore, a new method to estimate shoreline changes based on the superimposition of vectors extracted from both sources of SAR data has indicated that the shoreline has been subjected to severe coastal erosion responsible for retreat of 32 km2 and accretion of 20 km2, resulting in a mangrove land loss of almost 12 km2. In an application perspective, orbital and airborne SAR data proved to be a fundamental source of information for both geomorphological mapping and monitoring coastal changes in moist tropical environments.