A constante evolução dos equipamentos e softwares na área de topografia propiciou um ganho considerável em produtividade e qualidade na confecção dos mapas que servem de base aos projetos de Engenharia. O propósito deste trabalho é a analise comparativa dos dados de altimetria obtidos por três diferentes equipamentos de grande uso no mercado nacional, ou seja, a Estação total, GPS geodésico e GPS navegação, a fim de podermos avaliar a possibilidade do uso dos equipamentos rastreadores GPS para elaboração da hipsometria terrestre. Á área em estudo encontra-se no Campus "Luiz de Queiroz" da Universidade de são Paulo, no município de Piracicaba, Estado de São Paulo, cujas coordenadas aproximadas são: latitude de 22 o 42´40 "S e longitude de 47 o 37´30" W, sendo os dados coletados no mês de julho de 2002. Para avaliar o desempenho dos receptores GPS de Navegação e Geodésico em levantamentos altimétricos para fim de sistematização de terras, foram levantadas áreas com declividades diferentes (0 a 1%; 2 a 4% e 5 a 8%), simultaneamente pelo método topográfico convencional, utilizado uma Estação Total, de acordo com a NBR 13.133 - Execução de Levantamento Topográfico, e com os receptores GPS, sendo posteriormente calculados os volumes de terras para a comp aração dos resultados. De acordo com a metodologia empregada e os resultados obtidos, as principais conclusões foram: a) foi possível avaliar o erro cometido pelos equipamentos descritos, confirmando assim a possibilidade de uso do GPS Geodésico e descartando o uso do GPS de navegação para fins de sistematização de terras; b) com o uso do GPS diferencial os volumes entre os MDTs (Estação Total x GPS Geodésico) analisados em nove áreas com declividades diferentes esta em média 0,67% quando comparada as superfícies geradas, o que pode ser considerado como aceitável, e não significativo quando da execução dos serviços de sistematização terras o que vem ratificar o uso do equipamento GPS geodésico, se utilizados conforme a metodologia adotada. / The constant evolution of the equipments and softwares in the surveing field has brought a lot of gain in productivity and quality to make maps that are the foundation for the engineering projects. The purpose of this work is the comparative analyses of the data obtained by 3 different equipments that are very used in the national market - the Total Station, the Geodetic GPS and the Navigation GPS- in order to be able to evaluate the possibility of the use of the tracking GPS equipments for the elaboration of the terrestrial hypsometry. The studied area is in the "Luiz de Queiroz" Campus, in the University of São Paulo, in the city of Piracicaba, São Paulo state, whose approximate coordinates are: 22 42’40"S of latitude, and 47 37’30" W of longitude, these datum are from July 2002. According to the applied methodology and the obtained result, the main conclusions are: a) it was possible to evaluate the mistake by the described equipments, confirming the possibility of the use of Geodesic GPS and discarding the use of the Navigation GPS for land systematization; b) with the use of the differential GPS, the volume between the MDTs (Total Station x Geodesic GPS) analyzed in three different areas, the average is 067%, which can be considered acceptable, and not meaningful when from the execution of the land systematization services, what ratifies the use of the Geodesic GPS equipment, if used according to the applied methodology.

Pendant la dernière décennie, il y a eu un incrément de la résolution spatiale des observations satellitaires. Cela est notamment dû aux avancées technologiques implémentées sur les satellites. La quantité d'information observée est vaste, et il faut donc identifier des techniques efficaces pour la traiter et pour produire de cartes précises de la dynamique en surface. La mission future SWOT collectera de données d'élévation de surface (SSH) à très haute résolution spatiale : une partie de la dynamique à petites longueurs d'onde, c'est-à-dire, de la sousméso-échelle, sera représentée dans ces observations. Les observations satellitaires servent à réaliser la reconstruction spatiale en surface et aussi à la projeter vers l'intérieur de l'océan et vers des autres variables. La question posée est donc quelles méthodes peuvent fournir ces estimés 3D et multivariés avec une bonne précision à des échelles proches de la sousméso-échelle.Nous nous situons dans ce travail de thèse dans un cadre d'assimilation de données et d'images : l'objectif du travail étant la reconstruction de façon précise de la dynamique dans la couche de surface de l'océan (~500 m) à partir d'observations satellitaires. Pour ce faire, nous implémentons une méthode qui utilise différentes observations en surface à deux étapes d'analyse séparées. Elle consiste d'abord d'une première étape d'assimilation de données qui réalise une correction linéaire de l'écoulement. La deuxième étape se base dans une méthode d'assimilation d'images (Gaultier et al, 2012) dont l'objectif est de bien localiser les structures lagrangiennes obtenues par le calcul des exposants de Lyapunov. Dans le but de fournir des incertitudes associées aux estimés, nous disposons d'une distribution de probabilité d'ébauche qui sera corrigé par notre méthode : (i) la première étape effectue une analyse SEEK pour corriger cette distribution d'ébauche en utilisant une observation d’élévation de SSH; (ii) la deuxième étape minimise une fonction coût en utilisant l'observation d'une image structure et nous obtenons ainsi une distribution de probabilité finale. Les estimés sont projetés dans la dimension verticale en utilisant des EOFs (Empirical Orthogonal Functions) 3D multivariées, de cette sorte nous avons des estimés de variables observées et des variables non-observées (Duran-Moro et al, 2017).La méthode est testée en utilisant des données synthétiques produites par un modèle numérique à haute résolution (~3 km) dans la Mer de Salomon (SOSMOD36). La méthode fournit des résultats positifs : les estimés sont bien reconstruites sur la vertical et aussi concernant les variables non-observées. Dans ce cadre, nous réalisons une évaluation de l'impact de diverses pseudo-observations altimétriques dans la performance de la méthode. Ceci est réalisé par l'implémentation des traces Jason et Envisat sur l'observation de SSH ainsi qu'à partir du simulateur SWOT développé au JPL. Ce dernier est utilisé pour générer des pseudo-observations SWOT ainsi que des erreurs et du bruit prévus pour cette mission. La corrélation significative de ces erreurs a motivé l'application de la technique dans Ruggiero et al, 2016 dans notre analyse. Des simulations à plus haute résolution spatiale (~1 km) récemment produites à partir du modèle numérique NATL60 en Atlantique Nord sont aussi utilisées pour tester la méthode. Cette étude permet d'évaluer la dépendance des résultats avec la variabilité saisonnière de la dynamique aux moyennes latitudes. / During the last decade, high resolution observations have significantly increased mainly due to the strong innovations of satellite technology. The amount of observed information from satellites is large, and it is necessary to identify effective techniques to treat and to generate surface maps of the ocean dynamics. The future SWOT mission will collect sea surface height (SSH) measurements with a high spatial resolution : some dynamics at small wavelengths, which is known as submeso-scale, will be present in these new observations. Satellite observations could be used to carry out a vertical projection into the deeper ocean and to other variables. The question that rises is which methods can be used to carry out a 3D multivariate analysis with a significant precision, especially at meso and submeso-scale.We work here in a data/image assimilation framework : our objective if to reconstruction with good precision the dynamics in the upper oceanic layer (~500 m) using satellite observations. To do so, we implement a two-step method that uses different observations of the sea surface. The first step consist on the SEEK filter which is a data assimilation technique to carry out a first linear correction of the flow. The second step uses an image assimilation method (Gaultier et al , 2012) to correct the location of the main dynamical structure. This main dynamical structure is obtained by the computation of the Lyapunov exponents. A probability approach is applied to provide uncertainties on the estimates at each step. A first probability distribution of a background state is supposed to be known : the two-step method corrects this probability distribution at each step in order to converge towards the real ocean state. The SEEK filter corrects the background probability distribution using a SSH observation. The second step continues this correction towards smaller scales by using an image structure observation. To carry out the vertical projection, an ensemble of 3D multivariate EOFs (Empirical Orthogonal Functions) is used (Duran-Moro et al, 2017).The method is tested using synthetic data generated by a numerical model in the Solomon Sea region (SOSMOD36). The spatial resolution of these simulations is of ~3 km. We evaluate the response of our method in an idealized case study by using pseudo-observations generated from the simulations. The method provides good results and the estimates are corrected also in the vertical and in terms of other variables. A more detailed exploration of the altimetric observation is realized, especially related to future SWOT observations. Errors of SWOT observations have strong spatial correlations and another technique needs to be used in our method : this modification is carried out following work done in Ruggiero et al, 2016. Simulations from another NEMO configuration in the North Atlantic region (NATL60) are also used to evaluate the method. This second test allows us to explore the method in a different latitude of the globe.

Ce travail de thèse présente une étude sur la circulation océanique de surface s'écoulantle long des talus continentaux (aux abords de l’isobathe 200 m) de la mer Méditerranée centrale. L'objectif étaitde mieux renseigner le schéma de circulation de surface dans la région et les régimes de variabilité associés ens’appuyant essentiellement sur les observations altimétriques conventionnelles (AVISO/X-TRACK) le longdes traces satellite, disponibles sur la période 1993-2015. Cette étude est également basée sur une utilisationcombinée des données spatiales de SST, de mesures in-situ hydrographiques et de courantométrieconjointement avec l'altimétrie. L'analyse a d'abord permis de caractériser la variabilité saisonnière et deproposer un nouveau schéma de circulation de surface, y compris pour les saisons intermédiaires, incluant unenouvelle branche de courant Atlantique sur le plateau continental Tunisien. Le second point fort de ce travailréside aussi dans la caractérisation du transport de surface et des modes de variations inter-annuelles de l'eauAtlantique à partir de l'altimétrie côtière sur le long terme. L‘observabilité de la méso-échelle océanique de lazone d‘étude est enfin abordée à partir des mesures altimétriques haute résolution (AltiKa). Cela a permis dedétecter des structures physiques à plus fine échelle et d'affiner le détection des variations des courants les pluscôtiers. Au delà des aspects scientifiques, cette thèse a également permis des avancées méthodologiquesimportantes concernant l’utilisation combinée de différents jeux de données spatiaux et in-situ, aisémentapplicables pour les pays du Sud. / This work presents a study on surface ocean circulation flowing along the continentalslopes (near the 200 m isobath) of the central Mediterranean Sea. The aim was to better inform the surfacecirculation patterns in the region and the associated variability regimes based mainly on along-trackconventional altimetry (AVISO / X-TRACK) available over the period 1993-2015. This study is also based onthe combined use of spatial SST data, in-situ hydrographic and current measurements in conjunction withaltimetry. The analysis has first allowed to characterize the seasonal variability and to propose a new surfacecirculation pattern, including the intermediate seasons, and a new branch of Atlantic current on the Tunisiancontinental shelf. The second highlight of this work is the characterization of surface transport and inter-annualvariations of Atlantic water from coastal altimetry over the long term. The observability of the oceanic mesoscaleof the study area is finally addressed from high resolution altimetry measurements (AltiKa). This hasallowed to detect physical structures on a smaller scale and to refine the detection of variations in the mostcoastal currents. Beyond the scientific aspects, this thesis has also allowed important methodological advancesregarding the combined use of different spatial and in-situ data sets, easily applicable for the countries of theSouth.

Le satellite SWOT (Surface Water and Ocean Topography), dont le lancement est prévu aux horizons 2020, observera la hauteur d'eau sur les cours d'eau de largeur supérieure à 100 m, avec une répétitivité d'environ 5 jours sur la France, en repassant tous les 21 jours au dessus du même point. Ces données serviront d'une part à valider les modèles hydrologiques, et d'autre part à améliorer leur utilisation pour le suivi hydrologique. La finalité des travaux réalisés est d'assimiler des données SWOT virtuelles de hauteurs d'eau en rivière, en tenant compte de l'incertitude attendue des observations. À partir des produits d'assimilation, l'enjeu final est d'optimiser les valeurs du coefficient de rugosité du lit de la rivière, paramètre déterminant dans les modèles hydrologiques pour la régulation des écoulements. Dans un premier temps, plusieurs développements du modèle hydrométéorologique régional ISBA/MODCOU sont effectués. Les objectifs principaux sont d'introduire la simulation de profondeurs d'eau pour permettre une comparaison simple avec les futurs produits SWOT dans la suite des travaux, mais aussi, de manière plus générale d'améliorer l'hydrodynamique du modèle, en particulier les variations temporelles de vitesse d'écoulement en rivière. La prise en compte d'une vitesse variable des écoulements en rivière permet d'améliorer de façon significative la qualité des simulations, validées sur des stations de mesure in situ localisés sur le réseau de rivières du bassin versant de la Garonne. La comparaison des sorties ISBA/MODCOU avec celles des modèles hydrauliques détaillés sur la Garonne aval montre que le modèle simule plutôt bien les variations temporelles de hauteur d'eau, mais n'est pas capable de renseigner localement de bonnes profondeurs (à cause de la forte hétérogénéité spatiale de la géomorphologie non prise en compte dans ISBA/MODCOU). Après avoir développé et évalué le modèle sur le bassin de la Garonne, la deuxième étape est alors de mettre en place un schéma d'assimilation de données permettant d'assimiler des produits synthétiques SWOT dans le modèle. Le système d'assimilation utilisé repose sur la méthode du " Best Linear Unbiased Estimator " (BLUE). Dans notre cas, les données SWOT virtuelles servent à améliorer un paramètre hydrologique déterminant dans ISBA/MODCOU : le coefficient de rugosité de la rivière. Etant donné que SWOT n'est pas encore en orbite, il est nécessaire de simuler les observations que le satellite fournira. Connaissant son orbite, il est possible de simuler la trace issue des repassages du satellite au dessus du bassin de la Garonne. On peut ainsi déterminer sur un cycle complet de 21 jours quelles rivières seront observées, et à quels instants. Une simulation ISBA/MODCOU de référence a servi pour créer des observations virtuelles. On connaît donc la réalité vers laquelle on souhaite tendre : ce type d'expérience est appelé " expérience jumelle ". Le but est ainsi de partir volontairement d'un état perturbé du modèle, et d'arriver à se rapprocher au cours des cycles d'assimilation vers notre réalité connue. Les résultats montrent que le système d'assimilation permet de converger vers la simulation de référence (± 1 Ks pour le coefficient de rugosité, ± 5 cm pour la hauteur d'eau) sous certaines conditions. La fin des travaux est consacrée à la prise en compte d'erreurs de mesures SWOT plus réalistes (liées à l'instrument embarqué sur le satellite, à la déformation des ondes dans l'atmosphère, etc.), ainsi qu'à l'assimilation de données de hauteurs d'eau issues de modèles hydrauliques détaillés sur la Garonne avale. De plus, étant donné que SWOT n'observera pas des profondeurs en rivières mais des élévations d'eau par rapport à un niveau de référence, l'assimilation de variations temporelles de hauteurs d'eau dans ISBA/MODCOU est testée. / The SWOT (Surface Water and Ocean Topography) mission will provide free water surface elevations, slopes and river widths for rivers wider than 100 m, with a repetitivity of about 5 days and a revisit time of 21 days over France. These data will allow to validate hydrological models and improve them to simulate the water cycle. The final goal is to assimilate virtual water surface elevations measured by SWOT, by taking into account the error of these measurements. By using these products, the goal is to improve the values of the roughness coefficient in a hydrological model. This coefficient is important because river flows are very sensitive to this parameter. First, several developpements are set up in the regional hydrometeorological model ISBA/MODCOU. These model improvements will make possible comparisons with the future SWOT products. The principal objective is to simulate river depths in order to make an easy comparison with the SWOT products in future works. This will also improve the hydrodynamics of the model, in particular the simulation of temporal variations of flow velocities in the river. The representation of a variable flow velocity significantly improves the quality of the simulations which are validated over in situ river gauges located in the Garonne catchment. The comparison of ISBA/MODCOU outputs with those of fine-scale hydraulic models in the downstream Garonne river shows that the temporal river height variations are well simulated, but that it is difficult to simulate locally the river depth (because the high spatial heterogeneity of the geomorphology is not taken into account in ISBA/MODCOU). After the developpement and evaluation of the model in the Garonne catchement, the second step is to build a data assimilation scheme able to assimilate synthetic SWOT data in the model. The data assimilation scheme is based on the " Best Linear Unbiased Estimator " (BLUE). In our case, virtual SWOT data are used to improve an important hydrological parameter in ISBA/MODCOU : the roughness coefficient of the river. Because SWOT is not yet in orbit, it is necessary to simulate future satellite observations. By knowing the orbit, it is possible to simulate the swath and revisit times of the satellite above the Garonne catchment. We can also know over a complete cycle of 21 days which rivers will be observed and when. A reference simulation of ISBA/MODCOU has been run to create virtual observations. In this way, we know the reality to which we want to tender. This kind of experiment is called " twin experiment ". The goal is to start volontary from a pertubed state of the model, and then to converge in the assimilation cycles to the known reality. Results show that the data assimilation system let to converge in the direction of the reference simulation (± 1 Ks for the roughness coefficient, ± 5 cm for the river height). The representation of more realistic SWOT errors is implemented at the end of the work (linked to the instrument on board, the deformation of the waves in the atmosphere, etc.), and also the data assimilation of river heights simulated by fine scale hydraulic models in the downstream Garonne. Furthermore, the assimilation of temporal variations of river depths in ISBA/MODCOU is tested, because SWOT will not observe river depths but surface water elevations above a known reference level.

<p>A common way to measure height in aerial vehicles is to use a radar height altimeter (RHM). Since the RHM transmits radar pulses that can be detected, a passive alternative would be desirable in military applications. The idea to use reflected signals from the Global Positioning System (GPS) as a bistatic radar, has been established over the last years. The GPS signals are already present and would not reveal aeroplanes in covert operations. </p><p>In this thesis, the use of reflected GPS signals as a bistatic, passive altimeter is examined. A simulation model has been developed and implemented, and simulations using the model have been done. Different types of ground cover have been investigated, both water and land types, with varying reflectivity and scattering behaviour. For larger terrain variations, e.g. mountains and valleys, a ground elevation database has been used. Furthermore, several parameters, like the antenna coverage and the satellite elevation angle, have been varied and the result of this examined. </p><p>The results of these simulations show that measuring height is possible for bothsea and land surfaces. The accuracy depends on several error factors, like a bias originating from surface roughness and measurement errors due to noise in the receiver. The simulations also show that the most important design parameter is the antenna, which must be designed to give a sufficiently large SNR, capture the specular reflection and avoid unwanted reflections.</p>

A radar altimetry satellite measures the height of sea surface globally. However, tide gauges, measuring Sea Level Height (SLH), are set up on the Earth surface. Hence, SLHs are involved in vertical motion of the Earth crust. In this study, vertical motions of Earth crust have been separated from sea level variations. After clustering of SSH observations with K-means approach, two outlier detection methods Pope and Interquartile (IQR) Tests are implemented in data. Afterwards, each altimetry measurement is relocated to the center point of own cluster by means of geoid height derived from Earth Gravitational Model 2008 (EGM08). Before application of Principal Component Analysis (PCA) to see behavior of SSH inbetween clusters, Lomb Scargle algorithm is run to realize power spectrum of every clustered observations distinctly. Besides, tide gauge measurements are used for extracting 68 constituents with T_Tide program from hourly tide gauge observations. Then, predicted signal is produced by means of classical tidal harmonic analysis. To get monthly and daily mean values of hourly data, MSDOS Processing and Quality Controlling Software (SLPR2) has been run and the results are compared with Permanent Service for Mean Sea Level (PSMSL) monthly mean sea level values. Afterwards, the trends from altimetry, tide gauge and GPS are investigated to reveal vertical land motion. This study shows that sea level is rising every year more or less 7 mm at the Mediterranean coast of Turkey. Although Iskenderun tide gauge subsides 50 mm every year, the other stations do not show huge amount of vertical motion.

This report compares surface elevation change and volume change esti- mates from three methods: repeat track (RT), crossover (CX), and overlapping footprints (OFP). These three methods use different approaches to group- ing elevation point measurements taken at different measurement epochs and estimating elevation change. Volume changes are calculated from elevation changes in the same manner for all three methods but differences in sampling resolution between the methods affect volume change estimates in different ways. The recently reprocessed Release 633 version of elevation measurements from the Geoscience Laser Altimeter System (GLAS), flown on the Ice, Cloud and land Elevation Satellite (ICESat), are used in this analysis. Both elevation changes and volume changes are compared for both the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Additionally, uncertainties in the estimates for each method are quantified and compared. Results are separated by drainage systems and by above/below 2000 m surface elevation for the GrIS. For the AIS, results are aggregated to the East, West, and Penin- vi sula regions. Volume change estimates agree well for the three methods for the GrIS, with estimates of -227.75 ± 2.12 km³/yr, -249.30 ± 3.42 km³/yr, and -218.24 ± 7.39 km³/yr for the RT, CX, and OFP methods, respectively. These estimates are similar to those published from previous studies. For the AIS, however, larger discrepancies are found in the estimates. This stems primarily from a large discrepancy in the volume change estimate of the East AIS, where the RT, CX, and OFP methods estimate volume changes of 33.39 ± 1.42 km³/yr, 46.42 ± 5.46 km³/yr, and -2.72 ± 2.12 km³/yr, respectively. It's not entirely clear why this large discrepancy exists in this particular region, and elevation change estimates for a few particular drainage systems in this region are examined. Previously published volume changes for the AIS also show a large scatter and more work must be done to reconcile the various estimates. Finally, the volume change uncertainties reported do not completely account for the discrepancies in most regions. Additional analysis must be done to completely quantify all error sources. / text

In the western tropical Atlantic, the North Brazil Current retroflection periodically sheds large anticyclonic rings, which then propagate northwestward. Between 1998 and 2000, the North Brazil Current Rings Experiment sampled a large number of these rings by shipboard and moored acoustic Doppler current profiler. Ten of the sampled rings are analyzed in this study, focusing on their sea surface dynamic properties. The rings exhibit a radial structure consisting of two regimes, an ``inner'' core region in near solid body rotation and an ``outer'' ring regime with an approximately exponentially decaying structure. The observations show a sharp change in vorticity at the regime transition and the presence of a strong opposite vorticity shield bounding the inner solid body core. We show that Gaussian models, commonly used to represent the surface expression of these and other rings, are adequate for determining the sea surface height anomaly but tend to poorly estimate other properties such as the maximum swirl velocity. Therefore, we propose a new two--part model as a better approximation of the rings' radial structure. According to the cyclogeostrophic balance approximation, the sea surface height distribution across the inner ring has a parabolic shape, while the outer ring has an exponential structure similar to the velocity field. Interestingly, many of the observed rings have an intensity very close to the theoretical limit for anticyclones at these latitudes, which is believed to be due to inertial instability. A climatology of the NBCR is developed from 17 years of satellite altimetry. Usually 5 to 7 NBCR are observed per year, leading to an average of 6.1 rings per year, higher than the previously accepted 5.5 rings per year. A new methodology, more robust and consistent, is developed to track the rings, showing an impressive skill. The methodology can be applied to any velocity field, including irregular data grids. In contrast to what was previously believed, the NBCR do have a seasonal cycle. While so clear in the number of generated rings the seasonal cycle is explicit in the rhythm of formation. The rings are usually formed every 30--70 days, being more frequent during the Spring, when they are generated in a regular pace of near 40 days. In the Fall, the rings are less frequent, with a longer and variable time interval between them. The generation of North Brazil Current Rings (NBCR) has been proposed from numerical simulations to result from westward propagation Rossby waves originating from the instability of the North Equatorial Countercurrent (NECC). Other mechanisms, such as instability of he North Brazil Current where it crosses the equator, are also possible, and the precise mechanisms controlling NBCR formation are still undetermined. Here the ``NECC wave mechanism'' for generation of the near surface NBCR is evaluated for the first time from observations -- 18 years of satellite altimetry. Using a Complex Principal Component analysis on maps of absolute dynamic topography, it is shown that the NECC is the origin of the coherent propagating rings along the NBCR corridor. In agreement with the results proposed from previous simulations, the modal solution has a longer wavelength before the retroflection and shorter wavelength along the ring corridor. The seasonal signal of the wave energy in the NECC is also found to be coherent with the seasonal production cycle of the rings, after taking into account phase lags due to wave propagation. It is therefore confirmed that the of NBCR shedding is defined by wave processes arising in the NECC. Further, in contrast with prior understanding, the NBCR are shown to have a seasonal signal that follows the seasonal cycle of the NECC intensity.

The goal of this project is to horizontally and vertically survey part of the area of University of South Bohemia and graphically proces data in scale of 1: 500. The project is comprised of the theoretical and practical technical process focused on obtaining results by GNSS, tacheometry, orthogonal and missing line rate methods. Outcome of this project si newly created map showing the current status of the site.

The aim of this project is to horizontally and vertically survey part of the area of University of South Bohemia in České Budějovice and graphically proces data in scale of 1:500. The project is comprised of the theoretical and practical technical process of obtaining results by terrestrial and GNSS methods. The final product of this project is newly created map showing the current status of the site.