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Future Geosynchronous Synthetic Aperture Radar (GEOSAR) missions will provide permanent monitoring of continental areas of the planet with revisit times of less than 24 h. Several GEOSAR missions have been studied in the USA, Europe, and China with different applications, including water cycle monitoring and early warning of disasters. GEOSAR missions require unprecedented orbit determination precision in order to form focused Synthetic Aperture Radar (SAR) images from Geosynchronous Orbit (GEO). A precise orbit determination technique based on interferometry is proposed, including a proof of concept based on an experimental interferometer using three antennas separated 10–15 m. They provide continuous orbit observations of present communication satellites operating at GEO as illuminators of opportunity. The relative phases measured between the receivers are used to estimate the satellite position. The experimental results prove the interferometer is able to track GEOSAR satellites based on the transmitted signals. This communication demonstrates the consistency and feasibility of the technique in order to foster further research with longer interferometric baselines that provide observables delivering higher orbital precision. This work has been supported by the Spanish Science, Research and Innovation Plan (MICINN) with Project Codes TEC2017-85244-C2-2-P and PID2020-117303GB-C21 and by Unidad de Excelencia Maria de Maeztu MDM-2016-0600 financed by the Agencia Estatal de Investigación, Spain.

This paper is focused on the design, implementation and testing of an active reflector, to be used to support deformation monitoring studies based on Synthetic Aperture Radar interferometry. The device is designed to work in C-band with Sentinel-1 data, operating at 5.405 GHz ± 50 MHz. A brief description of the active reflector is provided. It consists of two antennas and an amplifying section. The active reflector has been tested in different experiments. In this paper, we describe the experiment carried out in the Parc Mediterrani de la Tecnologia (Castelldefels, Barcelona). The result shows a strong correlation with temperature. A calibration test was carried out to experimentally derive a calibration curve to correct the effect of temperature on phase stability, This work is part of a project that has received funding from the European GNSS Agency under the European Union's Horizon 2020 research and innovation programme, with grant agreement No 776335, project GIMS, "Geodetic Integrated Monitoring System". This work has been partially funded by AGAUR, Generalitat de Catalunya, through the Consolidated Research Group RSE, "Remote Sensing" (Ref: 2017-SGR-00729).

This study proposes modifications to an existing automatic classification method of Persistent Scatterers Interferometry (PSI) time series (TS) and a new procedure to classify ground movements into seven classes. We also represent a technique to detect TSs affected by phase unwrapping errors and a reclassification part to detect stable points, which are incorrectly classified as moving points using the original method. Around 60 km2of Catalunya were classified using Sentinel-1 images and a PSI technique. The proposed method classified 78359 PS TS. This study provided the spatial distribution of ground movement classes and detected several time series anomalies. © 2021 Elsevier B.V. All rights reserved.

Estimating unknown absolute phase from a wrapped observation is a challenging and ill-posed problem that possibly leads to misinterpretation of interferometric SAR (InSAR) deformation results. In this study, we introduce a quality index to cluster post-phase unwrapping multi-master InSAR timeseries outputs based on the estimated phase residuals and redundancy of network of interferograms. The index is supposed to indicate the reliability of a timeseries, including the identification of persistent scatterers (PSs) possibly affected by phase unwrapping jumps. The algorithm was tested on two Sentinel-1 interferometric datasets with 622,991 and 95,398 PSs, generated from the PSI processing chain PSIG of the geomatics division of CTTC. Promising result have been achieved-especially in identifying erroneous PSs with phase unwrapping jumps. Along with existing temporal phase consistency checking algorithms, the approach could provide rich information toward a better interpretation of the deformation timeseries results. This work has been funded by AGAUR, Generalitat de Catalunya, in the framework of Resolution EMC/ 2459/2019, FI-2020.

Persistent scatterer interferometry (PSI) has been proved to be an advanced Interferometric Synthetic Aperture Radar (InSAR) technique used to measure and monitor terrain deformation. Two of the critical problems with InSAR have been the effect of the refractive atmosphere and decorrelation on the interferometric phases due to long spatial-temporal baseline. The low density of persistent scatterers (PS) in non-urban areas affected by spatial-temporal decoherence more seriously has inspired the development of alternative approaches. Sentinel-1 (S1) has improved the data acquisition throughout, and compared to previous sensors, increased considerably the differential interferometric SAR (DInSAR) and PSI deformation monitoring potential. This paper describes an innovative methodology to process S1 SAR data. Different with PSI, its most original part includes two key processing stages: high and low frequency splitting from wrapped phases, prior to atmospheric filtering, and final direct integration to generate the complete deformation with time series containing linear and nonlinear components. The proposed method has two fundamental advantages compared with traditional PSI approach: the final monitoring results with excellent coverage of coherent points and the generation of active maps even for the areas with serious deformation in short term to break through the inherent limitation of PSI. The effectiveness of the proposed tools is illustrated using a case study located in Catalonia (Spain). This methodology has supposed a definitive step towards the implementation of DInSAR based techniques to support decision makers against geohazards. In this work, the deformation procedures happened in three different areas of the Catalonia (Spain) are presented and analysed. The maximum accumulated subsidence of over – 60 cm induced by mining activity can be detected by proposed methodology with nice coverage from January 2017 to January 2019. These reported cases illustrate how DInSAR based techniques can provide detailed terrain deformation for geohazard activity with complex topographical conditions. The active deformation areas map can be generated in fast aimed at geohazard risk early warning and management., This work was partially supported by Scientific research project of Surveying and Mapping Geographic Information in Jiangsu Province (JSCHKY201904), in part by the Marine Technology Brand Major of Jiangsu Province (PPZY2015B116), and Jiangsu Ocean University's 2020 Higher Education Teaching Reform Research Project (JGX2020006).

Persistent scatterer interferometry (PSI) is a group of advanced interferometric synthetic aperture radar (SAR) techniques used to measure and monitor terrain deformation. Sentinel-1 has improved the data acquisition throughout and, compared to previous sensors, increased considerably the differential interferometric SAR (DInSAR) and PSI deformation monitoring potential. The low density of persistent scatterer (PS) in non-urban areas is a critical issue in DInSAR and has inspired the development of alternative approaches and refinement of the PS chains. This paper proposes two different and complementary data-driven procedures to obtain terrain deformation maps. These approaches aim to exploit Sentinel-1 highly coherent interferograms and their short revisit time. The first approach, called direct integration (DI), aims at providing a very fast and straightforward approach to screen-wide areas and easily detects active areas. This approach fully exploits the coherent interferograms from consecutive images provided by Sentinel-1, resulting in a very high sampling density. However, it lacks robustness and its usability lays on the operator experience. The second method, called persistent scatterer interferometry geomatics (PSIG) short temporal baseline, provides a constrained application of the PSIG chain, the CTTC approach to the PSI. It uses short temporal baseline interferograms and does not assume any deformation model for point selection. It is also quite a straightforward approach, which improves the performances of the standard PSIG approach, increasing the PS density and providing robust measurements. The effectiveness of the approaches is illustrated through analyses performed on different test sites. This work has been partially funded by AGAUR, Generalitat de Catalunya, through a grant for the recruitment of early-stage research staff (Ref: FI_B 00741) and through the Consolidated Research Group RSE, “Remote Sensing” (Ref: 2017-SGR-00729). It has been also partially funded by the Spanish Ministry of Economy and Competitiveness through the DEMOS project “Deformation monitoring using Sentinel-1 data” (Ref: CGL2017-83704-P) and by AGAUR.

A modification to the extended CLEAN deconvolution method for passive microwave interferometric radiometers is presented to account for the interferometer beam patterns that vary depending on the source position within the interferometer field of view. This method is developed for the newly proposed multisatellite rotating microwave interferometric radiometer concept for geostationary atmospheric sounding, which is found to have a spatially varying beam pattern. The proposed method is implemented by the piecewise application of Fast Fourier Transform (FFT)-based convolution, i.e., the image is divided into discrete segments, where the beam pattern is assumed to be constant within each segment. This approach allows the proposed method to exploit the speed advantage of the FFT. Applying this method to the proposed multisatellite interferometer shows a twofold improvement in the radiometric accuracy of the restored brightness temperature map, as compared with the constant beam pattern CLEAN.

The Hanbury Brown and Twiss (HB-T) effect is fundamental to understand the nature of light, with important applications, for instance in ghost imaging. In this work, some coherence properties of the light emitted by an artifificial source were investigated. In particular, the second-order coherence function in time was retrieved under different experimental conditions. The work included the generation of pseudothermal light by using distinct rotating diffusers. The emitters were then characterized by setting an intensity interferometer (also called Hanbury Brown-Twiss interferometer). This procedure allowed to measure the photon bunching, or equivalently whether and how photons were eventually grouped at the detector. The results showed that the variation of the rotation speed of the difuser played a role in the second-order temporal coherence function, particularly when low rotation speeds were considered.

Student will design, build and test experimental quantum optics systems to study the interaction of single atom-resonant photons and atom-resonant entangled photon pairs with atomic systems. Delta kick cooling (DKC) gives control over the free expansion of Bose-Einstein-Condensates for the purpose of atom interferometry. Recent projects and future proposals on how to apply DKC for cold atom interferometry in space missions are outlined. This thesis provides both a classical analytical as well as a numerical solution to the evolution of the atom cloud distribution in phase space of a thermal ensemble. It investigates how duration and strength of the kick will influence the same. Furthermore, a numerical solution to the Gross-Pitaevskii Equation for the DKC of a Bose-Einstein condensate is presented.

The lens-free interferometric microscope (?LIM?) developed at ICFO by Roland Terborg et al. offers a hybrid solution of differential interference contrast microscopy, interferometry and holography. It is an ultra-sensitive interferometric microscope used for the analysis of structures and defects on the surface or inside the bulk of transparent materials, that can be both in transmission and reflection. It is an evolving platform, both from a hardware and software perspective. One of the main tasks in this thesis was to add an image processing algorithm to the LIM platform that can be used to detect, mark and analyse optical phase features on or inside transparent samples. The segmentation algorithm, based on edge detection, watershed transform and K-means classification, is used to classify phase maps into background and feature. Once classified into a binary map, connected areas are assigned to an integer label and the properties of the underlying phase map are measured. This allows to perform a systematic quantitative and statistical analysis of phase features by discarding the information that is out of focus. When samples containing features of known size are measured, the algorithm can be tailored for a detailed analysis of these feature structures, not only in 2D but also in 3D. The segmentation and labelling algorithm is augmented into a labelling based autofocus, that is capable of finding features planes or layers with known geometric features. Several tests are performed to prove the capabilities of the segmentation and labelling algorithm both in 2D and 3D, in combination with the proposed autofocus. Part of this is an analysis of embedded refractive index structures inside a 1 mm thick glass slide. The structures are completely invisible to the human eye and other microscopes. The smallest features are 50 by 50 µm in size and induce an optical distortion equivalent to 10 nm on the wavefront of transmitted light. The LIM is capable of making them visible. The features can be segmented and analysed and the algorithm can find and reconstruct layers separated by only 450 µm.

We investigate the dynamics of a two-component Bose-Einstein condensate trapped in two coupled rings in ladder configuration. First, we derive from the two-component Gross-Pitaevskii equation a few state model for the angular momentum modes. Then, we analyse the stability of the stationary states by solving the Bogoliubov-de Gennes equations. Also, we study the dynamics of the system for an arbitrary population imbalance between the rings, characterizing the transition from Josephson oscillations to quantum self-trapping. We also derive the self-trapping condition for the bosonic mixture, finding simultaneous self-trapping of the two components.

Imaging Confocal Microscopes (ICM) are highly used for the assessment of three-dimensional measurement of technical surfaces. The benefit of an ICM in comparison to an interferometer is the use of high numerical aperture microscope objectives, which allows retrieving signal from high slope regions of a surface. When measuring a flat sample, such as a high-quality mirror, all ICM?s show a non-uniform flat result, but a complex shape of low frequencies. ISO 25178-607 states that a ?/10 calibration mirror with less than 0.5nm Sa roughness should be measured, and the result top Imaging Confocal Microscopes (ICM) are highly used for the assessment of three-dimensional measurement of technical surfaces. The benefit of an ICM in comparison to an interferometer is the use of high numerical aperture microscope objectives, which allows retrieving signal from high slope regions of a surface. When measuring a flat sample, such as a high-quality mirror, all ICM?s show a complex shape of low frequencies instead of a uniform flat result. Such shape, obtained from a ?/10, Sa < 0.5 nm calibration mirror is used as a reference for being subtracted from all the measurements, according to ISO 25178-607. This is true and valid only for those surfaces that have small slopes. When measuring surfaces with varying local slopes or tilted with respect to the calibration, the flatness error calibration is no longer valid, leaving what is called the residual flatness error. In this paper we show that the residual flatness error on a reference sphere measured with a 10X can make the measurement of the radius to have up to 10% error. We analyzed the sources that generate this effect and proposed a method to correct it: we measured a tilted mirror with several angles and characterized the flatness error as a function of the distance to the optical axis, and the tilt angle. New measurements take into account such characterization by assessing the local slopes. We tested the method on calibrated reference spheres and proved to provide correct measurements. We also analyzed this behavior in Laser Scan as well on Microdisplay Scan confocal microscopes.

The capabilities of an experimental setup combining the functions of a conventional microscope with a custom built self-mixing interferometer to characterize the contractile motion of living cells in both the transversal and longitudinal directions were explored. The use of discrete wavelets to denoise experimental signals combined with the application of a Hampel filter was shown to outperform standard denoising methods found in the self-mixing literature. Furthermore, an efficient iterative method to reliably estimate the optical feedback level and the linewidth enhancement factor was developed. Experimental displacements of microspheres, used as phantoms for living cells, were reconstructed with a resolution better than 0.15 lambda using the proposed reconstruction method. These results substantiate the claim that the proposed reconstruction method will enable the measurement of the contractile motion of individual cardiomyocytes with a resolution approaching 100 nm.

Space-borne Synthetic Aperture Radar (SAR) systems have demonstrated great effectiveness to survey wide areas, independently of the weather conditions and the day/night cycle. One of the most exploited applications is Differential SAR Interferometry (DInSAR), and by extension, advanced multi-temporal techniques addressed as Persistent Scatterers Interferometry (PSI). These techniques provide the means to retrieve the displacement on the observed terrain surface. Taking advantage of the high coverage provided by this technology, natural and human induced phenomena may be monitored and detected in order to avoid and prevent hazardous or even catastrophic situations. A good characterization of such events is often related to the density and quality of the information delivered. In many cases, the success in the interpretation of localized surface motion phenomena relies on having as much measurements as possible. Conventional insitu techniques, when used properly, are able to provide reliable measurements. However, they are limited to their localization, and deploy a high number of instruments is not cost effective. The good characterization provided by PSI measurements is limited by the acquisition parameters and the actual scene under monitoring. SAR images sensitivity over the scene depends strongly on the geometric shape and distribution of targets. Historically, satellite SAR sensors had single polarimetric capabilities, so sensitivity over the scene was restricted to a certain antenna configuration. On the contrary, polarimetric acquisitions emit an receive with different antenna configurations, providing sensitivity to different geometries in the scenario. The launch in these later years of several satellites with polarimetric capabilities has triggered its use in several fields of application. The objective of this thesis is to evaluate the use of Polarimetric SAR (PolSAR) data for its application in the PSI framework. The extra information contained in PolSAR datasets is bound to improve the effectiveness of PSI techniques. Obtaining a higher density and quality of motion measurements will ease the detection and interpretation of terrain displacement phenomena., Els Radars d'Obertura Sintètica (SAR) embarcats en satèl·lits han demostrat ser molt efectius per monitoritzar grans àrees, independentment de les condicions atmosfèriques i del cicle dia/nit. L'aplicació més explotada es l'Interferometria Diferencial SAR (DInSAR), i per extensió, les tècniques avançades de processament multi-temporal anomenades Interferometria de Reflectors Persistents (PSI). Aquestes tècniques són capaces de mesurar el desplaçament en superfície del terreny observat. Aprofitant la gran cobertura que s'aconsegueix amb aquesta tecnologia, fenòmens d'origen tant natural com humà poden ser detectats i controlats per evitar i prevenir situacions de perill o fins i tot catastròfiques. La bona caracterització d'aquestes situacions sovint es relaciona tant amb la densitat com en la qualitat de la informació obtinguda. En molts casos, l’èxit en la interpretació de moviments de terreny localitzats depèn de tenir tants punts de mesura com sigui possible. Les tècniques convencionals de mesura in-situ, quan s'usen de forma adequada, són capaces de donar mesures fiables. No obstant, la seva cobertura està limitada a la localització de l'instrument, i la instal·lació d’un gran nombre d'instruments no és una solució econòmica. La bona caracterització de l'àrea mesurada amb tècniques PSI està limitada pels paràmetres d'adquisició i les característiques de la pròpia escena observada. La sensitivitat de les imatges SAR depèn en gran mesura de la distribució i la forma geomètrica dels blancs mesurats. Històricament, els sensors SAR emetien en polarització simple, i per tant la sensitivitat a la escena estava restringida a aquesta configuració específica de la antena. Per altra banda, durant les adquisicions polarimètriques s'emet i es rep en diferents configuracions de l'antena. Això permet tenir sensitivitat a geometries diferents dins la mateixa escena. El llançament aquest últims anys de diferents satèl·lits amb capacitats polarimètriques ha permès el seu ús en diversos camps d'aplicació. L'objectiu d’aquesta tesi és avaluar l'ús de dades polarimètriques SAR (PolSAR) per la seva aplicació en el marc de les tècniques PSI. La informació addicional que contenen els conjunts d’adquisicions PolSAR ha de millorar l'efectivitat de les tècniques PSI. L'obtenció d'una millor densitat i qualitat de les mesures permet una millor detecció i interpretació dels fenòmens de desplaçament superficial del terreny.

The first three of a series of new generation satellites operating at L-band microwave frequencies have been launch in the last decade. L-band is particularly sensitive to the presence of water content in the scene under observation, being considered the optimal bandwidth for measuring the Earth's global surface soil moisture (SM) over land and sea surface salinity (SSS) over oceans. Monitoring these two essential climate variables is needed to further improve our understanding of the Earth's water and energy cycles. Additionally, remote sensing at L-band has been proved useful for monitoring the stability in ice sheets and measuring sea ice thickness. The ESA's Soil Moisture and Ocean Salinity (SMOS, 2009-2017) is the first mission specifically launched to monitor SM and SSS. It carries on-board a novel synthetic aperture radiometer with multi-angular and full-polarization capabilities. NASA's Aquarius (2011-2015) was the second mission, devoted to SSS monitoring with a combined real aperture radiometer/scatterometer system that allows correcting for sea surface roughness. NASA's Soil Moisture Active Passive (SMAP, 2015-2018) is the second mission dedicated to measure SM. It carries on-board a real aperture full-polarimetric radiometer and a synthetic aperture radar (SAR) for enhanced spatial resolution and freeze/thaw detection. This Ph.D. Thesis is focused on analyzing the geophysical information that can be obtained from L-band SMOS, Aquarius and SMAP observations. The research activities are structured as follows: -Inter-comparison of radiometer brightness temperatures at selected targets. A novel methodology to measure the consistency between SMOS and Aquarius radiometric data over the entire dynamic range of observations (land, ice and ocean) is proposed. It allows detecting spatial/temporal differences or biases without latitudinal limitations neither cross-overs. This is a necessary step to combine observations from different instruments in a long term dataset for environmental, meteorological, hydrological or climatological studies. -Ice thickness effects on passive remote sensing of Antarctic continental ice. The relationship between Antarctic ice thickness spatial variations and changes detected by SMOS and Aquarius measurements is explored. The emissivity of Antarctica is analyzed to disentangle the role of the geophysical contributions (snow layers at different depths and subglacial lakes) to the observed signal. The stability of the L-band signal in the East Antarctic Plateau, calibration/validation site for microwave satellite missions, is assessed. -Microwave/optical synergy for multi-scale soil moisture sensing. The relationship of SM and land surface temperature (LST) dynamics is evaluated to better understand the fundamental SM-LST link through evapotranspiration and thermal inertia physical processes. A new approach to measure the critical soil moisture from time-series of spaceborne SM and LST is proposed. The synergistic use of SMOS SM and remotely sensed LST for refining SM disaggregation algorithms is also analyzed. -Comparison of passive and active microwave vegetation parameters. Recent research has shown that microwave vegetation opacity, sensitive to biomass and water content, and albedo, related to canopy structure, can be retrieved from passive L-band observations. The relationships between these two parameters and radar-derived vegetation descriptors have been explored using airborne observations from the SMAP Validation Experiment 2012 (SMAPVEX12). The obtained relations could allow for improved SM retrievals in active-passive systems, and also to estimate the vegetation properties at high resolution using SAR observations. The Ph.D. Thesis has been developed within the activities of the Barcelona Expert Centre (BEC). The presented results contribute to the use of L-band remote sensing in different scientific disciplines such as climate, cryosphere, hydrology and ecology., Els primers tres d'una sèrie de satèl·lits de nova generació funcionant a la banda L han sigut llançats a l'última dècada. La banda L es molt sensible a la presència d'aigua a l'escena observada, sent considerada òptima per mesurar la humitat del sòl (SM) i la salinitat del mar (SSS) de manera global a la superfície de la Terra. Monitoritzar aquestes dues variables climàtiques essencials es necessari per millorar el nostre coneixement dels cicles de l'aigua i l'energia. La teledetecció a banda L també ha sigut útil per monitoritzar l'estabilitat de les capes de gel i mesurar el gruix de gel marí. La missió Soil Moisture and Ocean Salinity (SMOS, 2009-2017) de l'ESA és la primera específicament llançada per monitoritzar SM i SSS. Porta un nou radiòmetre d'apertura sintètica amb capacitat multiangular i polarització completa. La missió Aquarius (2011-2015) de la NASA va ser la segona, dedicada a monitoritzar SSS amb un sistema de radiòmetre/escateròmetre d’apertura real que permet corregir la rugositat de la superfície del mar. La missió Soil Moisture Active Passive (SMAP, 2015-2018) de la NASA és la segona dedicada a mesurar SM. Porta un radiòmetre d'apertura real i polarització completa i un radar d'apertura sintètica (SAR) per una millor resolució espaial i detecció de congelació/descongelació. Aquesta tesi està enfocada en analitzar la informació geofísica que pot obtenir-se de les observacions a banda L d'SMOS, Aquarius i SMAP. La seva investigació està estructurada com: -Intercomparació de temperatures de brillantor en zones seleccionades. Es proposa un nou mètode per mesurar la consistència entre les dades radiomètriques d'SMOS i Aquarius sobre el rang dinàmic complet d'observacions (terra, gel, oceà). Això permet detectar diferències espaials/temporals o biaixos sense limitacions latitudinals ni creuaments. Aquest pas es necessari per combinar observacions de diferents instruments en un llarg conjunt de dades per estudis mediambientals, hidrològics o climatològics. -Efecte de gruix de gel en teledetecció de gel continental a l'Antàrtida. S'explora la relació entre les variacions espaials del gruix de gel antàrtic i els canvis detectats a les mesures d'SMOS i Aquarius. L'emissivitat de l'Antàrtida es analitzada per discernir el rol de les contribucions geofísiques (capes de gel a diferents profunditats i llacs subglacials) al senyal observat. S'avalua l'estabilitat del senyal a banda L sobre la zona est de l'altiplà antàrtic, lloc per calibratge/validació de satèl·lits de microones. -Sinèrgia de microones/òptic per teledetecció de SM multiescala. S'avalua la correlació entre la SM i la temperatura de la superfície del sòl (LST) per entendre millor la relació SM-LST a través de processos físics d'evapotranspiració i inèrcia tèrmica. Es proposa un nou mètode per mesurar la humitat crítica utilitzant sèries temporals de SM i LST de satèl·lit. S'analitza l'ús de la SM de SMOS amb la LST de teledetecció per refinar algorismes de desagregació de SM. -Comparació de paràmetres passius i actius de microones relatius a la vegetació. Recent investigació ha mostrat que l'opacitat, sensible a la biomassa i el contingut d'aigua, i l'albedo, relacionat amb l'estructura, poden ser recuperats d'observacions passives a banda L. S'exploren les relacions entre aquests dos paràmetres i estimadors de vegetació derivats de radar utilitzant les observacions d'avió de l'experiment de validació d'SMAP 2012 (SMAPVEX12). Les relacions obtingudes podrien permetre millors recuperacions de SM en sistemes actius/passius i estimar les propietats de la vegetació a alta resolució utilitzant mesures de SAR. La tesi s'ha desenvolupat dins les activitats del Barcelona Expert Centre (BEC). Els resultats presentats contribueixen a l'ús de la banda L a diferents disciplines científiques com la climatologia, la criosfera, la hidrologia i l'ecologia.

Se trata de mejorar las imágenes del satélite SMOS del que la UPC tiene acceso a los datos. Sobre los oceanos es necesario mejorar la calidad de las imágenes para todas las aplicaciones relacionadas con la salinidad. This Degree Thesis has been performed at the Remote Sensing Laboratory (RSLab), at the Department of Signal Theory and Communications of the Universitat Politècnica de Catalunya. It consists on a set of strategies devoted to enhance the calibration system of the SMOS satellite. Along this manuscript, the basics of 2D interferometry are introduced as well as a brief review of the SMOS mission evolution. In order to understand SMOS calibration system the fundamental equations are also outlined. From there on, new calibration strategies are introduced, offering re-processing methods whose main aim is enhancing SMOS final products, such as salinity maps. The results were presented at the 26th meeting of the calibration group from the SMOS Expert Support Lab (ESL) . Este trabajo de fin de grado (TFG) ha sido realizado en el Remote Sensing Laboratory (RSLab) del Departamento de Teoría y Señal de Comunicaciones (TSC) de la Universidad Politécnica de Cataluña. El trabajo consiste principalmente en un conjunto de estrategias cuyo objetivo final es mejorar el sistema de calibración del satélite SMOS. A lo largo de esta memoria, los principios básicos de la interferometría 2D serán introducidos así como una breve explicación de la evolución de la misión SMOS. Con el objetivo de entender el sistema de calibración de SMOS las ecuaciones fundamentales serán destacadas. A partir de entonces, nuevas estrategia de calibración serán analizadas, basándose principalmente en métodos de reprocesado cuyo objetivo principal es aumentar la calidad de los productos finales de SMOS, como por ejemplo, mapas de salinidad globales. Los resultados de este proyecto han sido presentados en el 26º congreso del grupo de calibración del SMOS Expert Support Lab (ESL) . Aquest treball de fi de grau (TFG) ha estat realitzat al Remote Sensing Laboratory (RSLab) del Departament de Teoria i Senyal de Comunicacions (TSC) de la Universitat Politècnica de Catalunya. El treball consisteix principalment en un conjunt d?estratègies que tenen com a objectiu final millorar el sistema de calibració del satèl·lit SMOS. Al llarg d?aquesta memòria, els principis bàsics de la interferometria 2D seran introduïts així com una breu explicació de l?evolució de la missió SMOS. Amb l?objectiu de comprendre el sistema de calibració de SMOS, les equacions fonamentals seran esmentades. Dit això, noves estratègies de calibració seran analitzades, basant-se principalment en mètodes de reprocessat amb l?objecti final d?augmentar la qualitat dels productes finals de SMOS, com per exemple, mapes de salinitat globals. Els resultats d?aquest projecte han estat presentats en el 26é congrés del grup de calibració del Expert Support Lab (ESL) .

The Earth is continuously monitored by sensors capable of providing diversified information about several phenomena. In particular Synthetic Aperture Radar (SAR) is able to observe the Earth in all-day and all-weather conditions. Differential SAR Interferometry (DInSAR) regards a set of techniques able to measure displacement of the terrain. In the last decades these techniques have become very powerful geodetic tools for land deformation monitoring and have gained a prominent role in several fields, ranging from geophysical to engineering, from commercial to civil protection purposes. Measurements of direction and magnitude of landslides phenomena, monitoring of subsidence movements due to natural events or human activity are some examples of DInSAR applications. These techniques allow not only the analysis of a single deformation episode but also to estimate, with millimetric precision, the temporal evolution of large-scale deformations phenomena occurring on the Earth surface. This research covers transversally several aspects within the DInSAR applications and particularly is focused on analyzing step by step the DInSAR algorithm of the Coherent Pixel Technic (CPT) developed by the Universitat Politècnica de Catalunya (UPC) highlighting the conditions for a correct estimation of the solution. The achieved precision can be really high but anyway it is important to understand all the limitations that can change from one data-set to another. Particular attention has been paid on analyzing the different deteriorating factors that can affect the estimation, such as the quality of the data, the atmospheric artifacts or the spatial and temporal sampling of the phenomenon. In this regard, a theoretical study on the propagation of the interferometric phase noise has been carried out and validated through simulations. For reducing the impact of the interferometric phase noise normally only pixels with a certain quality can be processed. These pixels can be selected through different methods described in detail in the literature. On the one hand, each selection technique is able to detect a specific kind of target at a determined resolution. On the other hand, there is an obvious compromise between the quality and the pixels¿ density over the scene. Indeed, working with high densities could increase the reliability and the accuracy of the final result as long as poor quality pixels are not included in the processing. In this regard, in this Thesis a combination of the different kinds of targets has been studied with the objective of a joint processing at different resolutions. Finally the constant growth of the spaceborne, airborne and ground-based SAR sensors in terms of technology and number of available devices could be the beginning for exploiting at the same time different data-set in a joint processing. The integration of data coming from different sensors with different orbits, different resolution, different carrier frequencies and incidence angles can help in covering in a better way a complex displacement scenario and can provide more complete information., La Tierra está continuamente monitorizada por una gran variedad de sensores e instrumentos capaces de extraer información muy diversa de distintos fenómenos geofísicos. En este contexto, los Radares de Apertura Sintética (SAR) orbitales, terrestres o aerotransportados, están protagonizando un interés creciente, ya que permiten monitorizar escenarios de naturaleza muy diversa con independencia de las condiciones meteorológicas, operando tanto de día como de noche. Entre las diferentes aplicaciones que permiten explotar imágenes SAR, la Interferometría Diferencial SAR (DInSAR) ha adquirido una gran relevancia, permitiendo la monitorización de desplazamientos complejos de forma remota y con una elevada precisión. De hecho, en las últimas décadas, esta técnica se ha convertido en una herramienta geodésica de gran utilidad para el control del desplazamiento de superficies, adquiriendo un papel muy destacado en una gran variedad de áreas de investigación y comerciales: mediciones de dirección y magnitud en deslizamientos, control de fenómenos de subsidencia debido a eventos naturales o actividades humanas, etc. Las técnicas DInSAR no sólo permiten medir un episodio de deformación aislado sino también estimar, con precisiones milimétricas, la evolución temporal de desplazamientos de gran escala. En la presente Tesis doctoral se investigan de forma transversal varios aspectos en el marco de aplicaciones DInSAR y, en particular y de una forma más exhaustiva, el algoritmo Coherent Pixel Technique (CPT) desarrollado por la Universidad Politécnica de Cataluña (UPC), remarcando las condiciones de contorno necesarias para la correcta estimación de las soluciones. A pesar de que la precisión en los resultados obtenidos puede ser elevada, es de extremada importancia analizar en profundidad las limitaciones existentes para los distintos escenarios posibles. En este contexto, se ha prestado una especial atención al análisis de los diferentes factores de error que pueden afectar a la estimación, tales como la calidad de los datos, los artefactos atmosféricos o el muestreo espacial y temporal del fenómeno bajo observación. Con este propósito, se ha desarrollado un estudio teórico detallado relacionado con la propagación del ruido de fase interferométrica a lo largo de la cadena de procesado DInSAR, que a su vez ha sido validado mediante datos simulados. Con el objetivo de reducir el impacto del ruido de fase interferométrica, únicamente aquellos píxeles del escenario que cumplen con unos ciertos parámetros de calidad de fase deben ser incluidos en el procesado. Estos píxeles pueden ser seleccionados previamente a través de diferentes metodologías que se describen en detalle en la literatura. Por un lado, ha de tenerse en cuenta que cada una de estas técnicas es adecuada para un determinado tipo de blanco y resolución. Por otro lado, ha de remarcarse que existe un compromiso claro entre calidad y densidad. Efectivamente, trabajar con densidades elevadas favorece la fiabilidad del procesado y la utilidad de los resultados finales, siempre y cuando no sea a expensas de incluir píxeles de mala calidad. Con este propósito, en este trabajo de Tesis doctoral se propone la combinación de los distintos tipos de blanco a distintas resoluciones, obtenidos con los distintos métodos de selección disponibles, para la realización de un procesado conjunto. Finalmente, el crecimiento de sensores SAR aerotransportados y terrestres, en términos de tecnología y número de dispositivos disponibles, podría ser el comienzo para la explotación conjunta de datos desde múltiples plataformas. En este contexto, se muestra como la integración de los datos procedentes de diferentes sensores con distintas órbitas, resolución, frecuencia y ángulo de incidencia favorecen la obtención de mayores coberturas y mejoran el proceso de estimación de desplazamiento, dando lugar a una información más completa y detallada.

In this Ph. D. dissertation the electromagnetic bias in GNSS-R (Global Navigation Satellite Systems Reflectometry) altimetry has been studied. GNSS-R altimetry is a new type of system that uses navigation signals as signals of opportunity for Earth observation. The electromagnetic bias has been a topic of research for several decades in conventional radar altimetry, typically at C and Ku bands, and pointing in the nadir direction, but it is a new subject in altimetry GNSS-R. Previous studies on the electromagnetic bias have been first reviewed: the Weakly Non-Linear theory (WNL), the Modulation Transfer Function (MTF), and a combination of both models. After a brief study of both the WNL and the MTF, a combined method is selected, simulated and validated at Ku and C bands, and then extrapolated at L band, the band of the GNSS signals. Then, the EM bias is studied in the time domain and it is characterized using statistical descriptors. Finally, the impact of natural phenomena such as rain, waves and currents in the electromagnetic bias is calculated. In conclusion, this dissertation has demonstrated that the electromagnetic bias is not only a function of the wind speed (or waves), but also a function of both the incidence and azimuth angles. The study in the time domain has been shown that it exhibits a non-linear behavior. Moreover, heavy rains decrease the electromagnetic bias, as they damp the waves, while sea currents in the opposite direction of the wind speed increase the electromagnetic bias, because they increase the surface "roughness", while currents with the same direction of the wind, reduce it, En esta tesis doctoral se estudia el sesgo electromagnético en altimetría GNSS-R (Global Navigation Satellite Systems Reflectometry). La altimetría GNSS-R es un nuevo tipo de sistema que utiliza las señales de navegación como señales de oportunidad para la observación de la tierra. El sesgo electromagnético ha sido un tema de investigación durante varias décadas en altimetría radar convencional utilizando típicamente las bandas C y Ku, y apuntando en la dirección nadir, pero es un tema novedoso en altimetría GNSS-R. En primer lugar se revisan los estudios previos sobre el sesgo electromagnético: la Weakly Non-Linear theory (WNL), la Modulation Transfer Function (MTF), y modelos combinados de ambos. Después de un breve estudio tanto de la WNL como de la MTF, se selecciona un modelo combinado, se simula, y valida en las bandas C y Ku, y luego es extrapolado a la banda L, la banda de las señales de los GNSS. En segundo lugar, se estudia el sesgo electromagnético en el dominio del tiempo y es caracterizado utilizando descriptores estadísticos. Por último, se calcula el impacto de los fenómenos naturales como la lluvia, el oleaje y las corrientes en el sesgo electromagnético . En conclusión, esta tesis doctoral ha demostrado que el sesgo electromagnético no es sólo una función de la velocidad del viento (o del oleaje), sino que también es una función tanto del ángulo de incidencia, como del ángulo de acimut. El estudio en el dominio del tiempo ha demostrado que tiene un comportamiento no lineal. Por otra parte, las fuertes lluvias disminuyen el sesgo electromagnético, pues amortiguan las olas, mientras que las corrientes con dirección opuesta al viento aumentan el sesgo electromagnético, pues aumentan la "rugosidad" superficial, mientras que la corriente tiene la misma dirección de la velocidad del viento, lo reduce.

In this manuscript we present an experimental and theoretical investigation of quantum-noise-limited measurement by nonlinear interferometry, or from another perspective, quantum-noise-limited interaction-based measurement. The experimental work is performed using a polarization-based quantum interface between propagating light pulses and cold rubidium-87 atoms trapped in an optical dipole trap. We first review the theory of quantum metrology and estimation theory, and we describe theoretical proposals for nonlinear quantum metrology as developed by the group of Carlton M. Caves in the University of New Mexico. We then describe our proposal, made in 2010, to implement the Caves group's ideas using nonlinear optical interactions in a cold atomic ensemble to implement a nonlinear spin measurement. To evaluate this proposal we develop two theoretical approaches, first an extension of the collective quantum variables approach, often employed to describe quantum interfaces and atomic spin ensembles, to nonlinear optical processes. This results in an effective Hamiltonian containing nonlinear terms of the form described by the Caves group, and demonstrates a qualitative equivalence of the two schemes. The second approach uses the Maxwell-Bloch equations to describe nonlinear propagation of pulses through an atomic spin ensemble, including inhomogeneities and relaxation effects. This latter method makes quantitative predictions about optical rotation signals under realistic experimental conditions. We then describe the implementation of the proposal in a polarization-based light-atom quantum interface. We describe the existing trapping and probing system, focusing on the characteristics that make it suitable for shot-noise-limited and projection-noise-limited atomic spin measurements. We then describe adaptations to use the apparatus with shorter, higher-intensity pulses as required for nonlinear measurement, as well as characterization of the photodetection system under these modified conditions. Calibration of the nonlinear polarization rotation versus probe laser detuning allows us to produce a nearly pure nonlinear rotation signal. Finally, experimental results are presented showing shot-noise-limited nonlinear rotation signals over three orders of magnitude in photon number N. The results are consistent with our theoretical models and confirm a major prediction of the Caves group's work, in that a two-photon interaction gives a scaling for the measurement sensitivity as N^{-3/2}. A brief discussion relates this experimental observation to theoretical discussions of the ¿Heiseinberg limit¿ of quantum metrology, and possible further applications of nonlinear measurement techniques., En aquest manuscrit presentem una recerca experimental i teòrica sobre mesures limitades pel soroll quàntic fetes mitjançant interferometria no lineal, o des de un altra perspectiva, mitjançant interacció. En el treball experimental es va fer servir una interfície quàntica de polarització entre polsos de llum en propagació i àtoms freds de rubidi-87 atrapats en una trampa òptica de dipol. Primer, farem un repàs de la teoria de la metrologia quàntica i de la teoria de la estimació, descriurem la proposició teòrica sobre metrologia quàntica no lineal tal i com la va desenvolupar el grup de Carlton M. Caves al Universitat de Nou Mèxic. A continuació descriurem la nostra proposta, feta al 2010, de com implantar la idea del grup de Caves fent servir interaccions òptiques no lineals en un conjunt d’àtoms freds amb la finalitat d’efectuar una mesura no lineal de spin. Per avaluar aquesta proposta vam desenvolupar dues aproximacions teòriques fent ús de dos mètodes diferents. En primer lloc vam estendre la tècnica de variables quàntiques col lectives cap als processos òptics no lineals, aquesta tècnica sovint és utilitzada per descriure interfícies quàntiques i conjunts de spin atòmics. Això dóna com a resultat un Hamiltonià efectiu que conté termes no lineals de la forma descrita pel grup de Caves, i demostra una equivalència qualitativa entre el nostre esquema i el seu. El segon mètode fa ús de les equacions de Maxwell-Bloch per descriure la propagació no lineal dels polsos a través del conjunt de spins atòmics, tenint en compte deshomogeneïtats i efectes de relaxació. D’aquesta manera podem fer prediccions quantitatives sobre senyals de rotació de polarització òptica en les condicions d’un experiment real. Seguirem amb la descripció de com vam implementar al laboratori la nostra proposta teòrica mitjançant una interfície quàntica de polarització entre llum i àtoms. Descriurem el ja existent sistema de confinament i sondeig dels àtoms, concentrant-nos en les característiques que permeten fer mesures al limit del soroll quàntic i del soroll de projecció. Aleshores detallarem com vam adaptar el sistema per l’ús amb polsos més curts i intensos, tal i com requereix la mesura no lineal, i al mateix temps com vam calibrar el sistema de detecció de llum en aquestes diferents condicions. El calibratge de la rotació no lineal de polarització en funció de la freqüència del làser de sonda, ens permet obtenir un senyal de rotació casi purament no lineal. Finalment, presentarem els resultats experimentals que mostren senyals de rotació no lineal limitats pel soroll quàntic al llarg de tres ordres de magnitud en el número N de fotons. Tals resultats son consistents amb els nostres models teòrics i confirmen una important predicció del treball del grup de Caves, és a dir que la interacció de dos fotons dóna una llei d’escala de N-3/2 per a la sensibilitat de la mesura. Per concloure, una concisa discussió relaciona aquesta observació experimental amb discussions teòriques sobre el “limit d’Heisenberg” de la metrologia quàntica, i amb d’altres possibles aplicacions de tècniques de mesura no lineal

This work has been undertaken within the frame of the FPI scholarship BES-2009-028505 of 30/07/2009, by the "Secretario de Estado de Investigación del Ministerio de Ciencia e Innovación", related to the project TEC2008-06764-C02-01 (Universitat Politècnica de Catalunya) titled "Advanced concepts on active and passive microwave remote sensing: technology and applications". In a more general scope, this thesis is related to the Remote Sensing Laboratory (Signal Theory & Communication Department, UPC) on-going activities, within the SMOS (Soil Moisture and Ocean Salinity) mission by the European Space Agency (ESA). These activities have been organized to provide original advances in the following four main topics: 1) SMOS system performance assessment. SMOS commissioning phase finalized in May 2010 providing preliminary performance results. Therefore, as a first step in this work, radiometric sensitivity and spatial bias (systematic spatial errors) have been reviewed and assessed. To achieve this, new techniques have been developed to better compare SMOS images to ground truth targets. SMOS ocean views have been selected as the best option since provide smooth brightness temperature distributions for which accurate models are available. 2) Spatial bias mitigation techniques. Spatial bias was a major issue in SMOS first images since it was larger than expected. In order to identify the dominant sources of spatial bias, each potential source of error, at calibration level,has been simulatedand compared tomeasured SMOS error patterns. 3) Spatial bias in the EAF-FoV. Whereas SMOS performance in the alias free FoV was well within mission requirements, this issue was especially important for the four polarimetric temperatures in the extended regions. This issuehas been addressed in two ways. First a new approach has been developed to systematically analyze spatial bias by splitting SMOS EAF-FoV into different regions of interest. Also, the pixels have been arranged per angle of incidence. Secondly, the impact in each region of calibration errors and different image reconstruction has been addressed. 4) Spatial bias in full-pol measurement.The main objective of this work has been achieved by developing, implementing and validating a SMOS full-pol G-matrix image reconstruction procedure that resulted into significantly improved polarimetric images. This tool allowed a comprehensive assessment of the two error contributions that have been identified as the main sources of residual spatial bias: the so-called floor error and antenna pattern uncertainty. Finally, as a validation of the quality of SMOS Level 1 fully polarimetric data that has been achieved, the last chapter of this work has been devoted to provide operational Faraday rotation retrievals in a per snap-shot basis.

Synthetic aperture radar (SAR) systems are inherently band limited in both range and azimuth, and hence, the point spread function (PSF) has the shape of a bidimensional sinc function. In addition, all SAR images are slightly oversampled, and as a consequence, the contribution of a single target extends to more than a single cell. The main lobe and the side lobes of strong scatterers are sometimes clearly visible in the images. This characteristic of the SAR images must be considered when applying differential interferometric synthetic aperture radar (DInSAR) pixel selection algorithms. For persistent scatterers, the properties, for instance, the amplitude stability, are preserved in both redundant information around the main lobe and side lobes. For this reason, a cluster of pixels rather than just the pixel position corresponding to the exact location of the target will be detected. Spatially variant apodization (SVA) is a nonlinear filter based on cosine-on-pedestal weighting functions able to achieve a total side-lobe cancelation without degrading the original image resolution. When working with complex data under complex scattering scenarios, the PSF moves away from the ideal bidimensional sinc, and the SVA performance worsens. The amplitude and phase of the original images could be distorted by the SVA filtering compromising the pixel selection and the quality of the final DInSAR results. In this letter, SVA is used to method locate in the image the side lobes of high-power scatterers and generate a mask while preserving the amplitude and phase of the original images.

Ground subsidence of detrital deposits in the Almer´ıa basin (SE Spain) was studied using the remote sensing technique of Differential Interferometry SAR (DInSAR). This basin is one of the most arid in Europe, receiving an average rainfall of 250 mm per year. Over the last 60 years the region has experienced an enormous agricultural and urban expansion, whose water demand has been largely supplied from groundwater, leading to the current situation of overexploitation of water resources. This paper outlines the likely relationship between groundwater abstraction and subsidence. To this end, 34 ERS and Envisat images, taken between 2003 and 2009, were analysed to estimate ground surface deformations, and hence, compared with water table variations measured in a number of piezometers in the basin. The analysis shows a clear parallelism between the variations in piezometric level and deformation of the ground surface. In addition, the zones of greatest subsidence coincide with those areas where groundwater abstractions are concentrated. Subsidence over the examined period varies from 10 to 30 mm, with extreme values as high as 50 mm, which translates to a rate of between 1Ð7 and 5 mm/year, reaching maximum rates of 8 mm/year at some points. Given such subsidence rates, damage to urban infrastructures are, for the moment, incipient.

Memoria de tesis doctoral presentada por Verónica González Gambau para optar al grado de Doctora por la Universitat Politècnica de Catalunya (UPC), realizada bajo la dirección del Dr. Francesc Torres Torrest y de la Dra. Nuria Duffo Úbeda.-- 178 pages, [EN] The variability of soil moisture and ocean salinity controls the continuous exchange of water between the oceans, the atmosphere and the land. Therefore, the accurate and periodic measurements of these geophysical variables are paramount to improve the climate change prediction and extreme-event forecasting. However, until very recently, global measurements of these parameters with a suitable spatial and temporal resolution have not been available. Real aperture radiometers have been frequently used for Earth observation applications. Nevertheless, for space-borne sensors at a low Earth orbit, the requirements on spatial resolution and coverage, at the operating frequencies (L-band), would require an unfeasibly large antenna. Conversely, synthetic aperture radiometry achieves high resolution using an array of small antennas, becoming a sound alternative to real aperture radiometry at low microwave frequencies. The ESA’s SMOS (Soil Moisture and Ocean Salinity) mission, successfully launched on November 2009, is the first mission ever attempted to frequently and globally measure soil moisture over the continents and sea surface salinity over the oceans. The single payload of the mission, the MIRAS (Microwave Imaging Radiometer by Aperture Synthesis) instrument, is the first space-borne L-band two dimensional synthetic aperture radiometer. This completely new type of instrument implies a technological challenge, for which the development of a detailed error model definition, dedicated calibration and image reconstruction algorithms have been needed. The calibration of MIRAS tackles all activities devoted to retrieve the SMOS scientific products from raw data measurements with the accuracy required by the scientific community. Characterization activities, mainly performed prior to the beginning of the in-orbit operation, have been required to develop and test the calibration activities. Within the framework of the SMOS mission, this Ph.D. Thesis is focused on the characterization of the interferometric radiometers devoted to Earth observation. The main contributions of this Thesis, which are directly related to the MIRAS payload performance assessment, are: (i) the definition of tests for the characterization campaigns, data processing methods and success criteria and (ii) the development of calibration algorithms and tools to fine-tune the instrument in order to fully achieve the system requirements and therefore the scientific requirements of the mission. Most of the work has been done in the framework of the MIRAS/SMOS Pre-Commissioning Phase activities and it has been completed in the framework of the Commissioning Phase preparatory work. Calibration tools and techniques developed for the MIRAS ground characterization have been adapted to fulfill in-orbit instrument characterization during the first months of the Commissioning Phase and contributed to the development and consolidation of the SMOS operational level-1 processing, [ES] La variabilidad de la humedad del suelo y de la salinidad de los océanos controla el continuo intercambio de agua entre los océanos, la atmósfera y la tierra. Por tanto, la obtención de medidas precisas y periódicas de estas dos variables geofísicas es fundamental para la mejora de la predicción del cambio climático y de la previsión de desastres naturales. Sin embargo, hasta hace muy poco no se disponía de medidas globales de estos parámetros con la resolución temporal y espacial necesaria para este tipo de aplicaciones. Los radiómetros de apertura real se han utilizado frecuentemente para aplicaciones de observación de la Tierra. Sin embargo, para sensores situados en órbitas bajas, los requerimientos de resolución espacial y cobertura, a la frecuencia de trabajo (banda L), implicarían el uso de una antena de unas dimensiones que no son viables tecnológicamente. Por el contrario, la radiometria de apertura sintética permite obtener una alta resolución utilizando un array de pequeñas antenas, convirtiéndose en una sólida alternativa a la radiometría de apertura real para frecuencias bajas de microondas. La misión SMOS, de la Agencia Espacial Europea, lanzada con éxito en Noviembre de 2009, es la primera misión para la medida frecuente y global de la humedad del suelo y la salinidad de los océanos. La única carga útil de la misión, el instrumento MIRAS, es el primer radiómetro de apertura sintética en dos dimensiones que es lanzado al espacio. Este tipo de instrumento, completamente novedoso, implica todo un reto tecnológico, por lo que han sido necesarios la definición de un modelo detallado de errores y el desarrollo de algoritmos específicos de calibración e inversión de imagen. La calibración del radiómetro MIRAS comprende todas las actividades dedicadas a recuperar los productos científicos de SMOS a partir de los datos crudos con la precisión requerida por la comunidad científica. Para poder desarrollar y probar las actividades de calibración ha sido preciso realizar campañas de caracterización del instrumento, llevadas a cabo en tierra principalmente. En el marco de la misión SMOS, esta tesis se centra en la caracterización de radiómetros interferómetricos para la observación de la Tierra. Las principales contribuciones de esta tesis, relacionadas directamente con la evaluación de las prestaciones del radiómetro MIRAS, son: (i) la definición de las medidas para las campañas de caracterización, métodos de procesado de datos y criterios de éxito y (ii) el desarrollo de algoritmos de calibración y herramientas que permitan el ajuste del intrumento para cumplir los requerimientos del sistema y por lo tanto, los requerimientos científicos de la misión. La mayor parte de este trabajo se ha realizado en el marco de las actividades previas al lanzamiento de la misión y se ha completado en el marco del trabajo preparatorio de la fase de comisionado (primeros meses de medidas en órbita). Las herramientas de calibración y las técnicas desarrolladas para la caracterización en tierra del instrumento se han adaptado para completar la caracterización del instrumento durante los primeros meses en órbita, contribuyendo al procesado de nivel 1 operacional

The Soil Moisture and Ocean Salinity (SMOS) mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA). It was a direct response to the global observations of soil moisture and ocean salinity. Its goal is to produce global of these parameters using a dual-polarization L-band interferometric radiometer the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). This instrument is a new polarimetric two-dimensional (2-D) Y-shaped synthetic aperture interferometric radiometer based on the techniques used in radio-astronomy to obtain high resolution avoiding large antenna structures. MIRAS measures remotely the brightness temperature (TB) emitted by the Earth's surface, which is not isotropic, since it depends on the incidence angle and polarization, the Soil Moisture (SM) or the Sea Surface (SSS), the surface roughness etc. among others. The scope of this doctoral thesis is the study of some potential improvements could eventually be implemented in future interferometric radiometers. To validate improvements a ground-based instrument concept demonstrator the Passive Advanced Unit Synthetic Aperture or (PAU-SA) has being designed and implemented. Both MIRAS and PAU-SA are Y-shaped array, but the receiver topology and the processing unit are different. This Ph.D. thesis has been developed in the frame of The European Investigator Awards (EURYI) 2004 project entitled "Passive Advanced Unit (PAU): Hybrid L-band Radiometer, GNSS Refectometer and IR-Radiometer for Passive Sensing of the Ocean", and supported by the European Science Foundation (ESF).

The Ground-Based Synthetic Aperture Radar (GB-SAR) is a relatively new technique, which in the last ten years has gained interest as deformation measurement and monitoring tool. The GB-SAR technique is based on an imaging radar-based sensor, which o ers high sensitivity to small displacements, in the region of sub-millimetres to millimetres, long-range measurements, which can work up to some kilometres, and massive deformation measurement capability. These features confer to the GB-SAR technique interesting advantages with respect to other point-wise deformation measurement techniques. The process of estimating deformation from the GB-SAR data is not straightforward: it requires complex data processing and analysis tools. This dissertation is focused on these tools, covering the whole deformation estimation process. This thesis collects the main research results achieved on this topic during my work at the Active Remote Sensing Unit of the Institute of Geomatics. Two di erent approaches for measuring deformation with GB-SAR data are described and discussed. The irst one is the interferometric approach, based on the exploitation of the phase component of the GB-SAR data, which is the commonly used GB-SAR method. The second one is a non-interferometric approach, which exploits the amplitude component of the GB-SAR data, o ering an interesting alternative way to exploit the GB-SAR data. This dissertation has two main objectives. The first one is presenting, step by step, a complete interferometric GB-SAR procedure for deformation measuring and monitoring. The second one is presenting two new algorithms, which represent the most innovative part of this thesis. The first algorithm faces the phase unwrapping problem, providing an automatic solution for detecting and correcting unwrapping errors, which is called 2+1D phase unwrapping. The second algorithm is the base of the above mentioned non- interferometric approach, which overcomes some of the most critical limitation of GB-SAR interferometry, at the expense of getting less precise deformation estimates. The dissertation is divided in 6 chapters. The first one is the introduction, while the second one provides an overview of GB-SAR interferometry, introducing the main aspects that are the basics of the subsequent chapters. Chapter 3 describes a complete GB-SAR processing chain. Chapters 4 and 5 contain the most original part of the dissertation, i.e. the 2D+1 phase unwrapping algorithm, and the non-interferometric approach. Finally, in Chapter 6 the conclusions are discussed and further research is proposed., El radar terrestre d’obertura sintètica (GB-SAR) és una tècnica relativament nova que, en els últims deu anys, ha guanyat interès com a eina per a mesurar i monitorar deformacions. La tècnica GB-SAR es basa en un sistema radar amb capacitat per proporcionar imatges, que ofereix una alta sensibilitat a petits desplaçaments, d’ordre mil·limètric o submil·limètric, que és capaç de mesurar a llargues distàncies (alguns km) i que té una alta capacitat per fer mesures massives. Aquestes característiques donen a la tècnica interessants avantatges respecte a altres tècniques clàssiques de mesura de deformacions, típicament basades en mesures puntuals. Derivar mesures de deformació a partir de dades GB-SAR no és un procés senzill, ja que requereix uns procediments complexos de processat i anàlisi de dades. Aquesta tesi es centra en aquests processos. Aquesta tesi recull alguns dels resultats més destacats de la investigació que he desenvolupat sobre aquest tema a la unitat de Teledetecció Activa de l'Institut de Geomàtica. Al llarg del document es descriuen dues aproximacions diferents per mesurar deformacions amb GB-SAR. Una es basa en la explotació de la tècnica de la interferometria, és a dir explotant la component de la fase de les imatges GB-SAR: és la tècnica GB-SAR usada habitualment. La segona, anomenada tècnica no-interferomètrica, es basa en la component de l’amplitud de les dades GB-SAR i ofereix una interessant alternativa a la primera. La tesi acompleix dos objectius principals. En primer lloc presenta un procediment complet per la mesura i monitoratge de deformacions mitjançant interferometria GB-SAR. En segon lloc, descriu dos nous algorismes que resolen problemes específics de la interferometria clàssica aplicada al GB-SAR i que representen la part més innovadora d’aquesta tesi. El primer algorisme aborda un dels problemes oberts de la interferometria, el phase unwrapping, proposant un mètode automàtic per detectar-ne i corregir-ne els errors. El segon algorisme proposa un nou mètode per a l'explotació de les dades GB-SAR per mesurar deformacions sense utilitzar la interferometria. La estructura de la tesi consisteix en sis capítols. Després de la introducció, el Capítol 2 proporciona una visió general de la interferometria GB-SAR, introduint els conceptes principals utilitzats en la tesi. En el tercer capítol es descriu una cadena de processament basada en GB-SAR interferomètric. Els capítols quart i cinquè contenen la part més original de la tesi: l'algorisme de phase unwrapping i el mètode no-interferomètric per la mesura de deformacions. Finalment, es discuteixen les conclusions principals i es proposen futures línies d’investigació.

Las técnicas de Interferometría Diferencial se basan en la combinación de varias imágenes SAR con distinta separación temporal y permiten la recuperación de las componentes lineales y no-lineales del proceso de deformación ocurrida en el entorno de interés durante el entero periodo de observación. Condición imprescindible para una correcta estimación de los fenómenos geodéticos es la elevada estabilidad de la plataforma que embarca el sensor SAR. Por esta razón, a nivel operativo se utilizan datos SAR satelitales.El objetivo de la Polarimetría SAR es describir el entorno de interés analizando las propiedades de la señal que éste dispersa cuando se utilizan diferentes combinaciones de polarización de las antenas transmisora y receptora, definidas canales polarimétricos. La polarimetría interferométrica SAR junta la capacidad de la polarimetría de separar mecanismos de dispersión independientes con la sensibilidad de la Interferometría a la altura de los correspondientes centros de fase, y permite describir la distribución volumétrica de los dispersores dentro de la escena observada. Debido a la falta de conjuntos de datos polarimétricos SAR satelitales que cubran tramos temporales suficientemente largos, hay aún un gran interés en las mejoras que la polarimetría podría aportar a técnicas ya consolidadas como las de Interferometría Diferencial.La actividad de investigación que se presentará en esta tesis doctoral abarca, por primera vez conjuntamente, las dos áreas de la Polarimetría SAR y de la Interferometría Diferencial utilizando el sensor radar terrestre de corto alcance (gbSAR) desarrollado por la Universitat Politècnica de Catalunyua (UPC). El trabajo constará de dos bloques principales.El primer bloque describirá las técnicas que se han desarrollado para convertir el sistema UPC gbSAR en un instrumento operativo y simplificar la utilización de sus adquisiciones, incluyendo la formulación matemática de los principios de funcionamiento del sistema, la cadena de procesado de los raw data y su calibración polarimétrica, los procedimientos de georeferenciación, y las técnicas de compensación de los artefactos atmosféricos presentes en sus medidas diferenciales.La segunda parte se ocupará de demostrar los beneficios que los datos SAR polarimétricos ofrecen respecto a la medición de un único canal polarimétrico para aplicaciones diferenciales. A fin de llevar a cabo esta tarea, se analizarán los datos gbSAR adquiridos durante una campaña de medidas de un año realizada en el pueblo de Sallent, en Cataluña, afectado por un fenómeno de subsidencia. En esta parte se analizarán tres temas principales. El primero es el comportamiento no estacionario en tiempo del entorno urbano bajo la geometría de observación del sensor terrestre. Se estudiarán en detalle los efectos de su inestabilidad y se propondrá una técnica de filtrado novedosa entallada a las propiedades de los blancos deterministas con el fin de preservar la información de la fase diferencial. El segundo tema abarca el problema de los efectos de troposfera en datos diferenciales con separación temporal superior al mes y de su separación de las variaciones de fase inducidas por el proceso de deformación. El tercer tema es la utilización de toda la información polarimétrica diferencial. Con fin de superar las limitaciones propias de las técnicas DInSAR clásicas, se propondrá un nuevo modelo polarimétrico de dispersión y se demostrarán las ventajas de la nueva formulación enseñando la mejor estimación del proceso de subsidencia en Sallent. En la parte final de este apartado se explorará también el potencial de las técnicas polarimétricas de optimización de la coherencia para aplicaciones diferenciales., Differential SAR interferometry (DInSAR) deals with the combination of multi-temporal SAR images for the estimation of the linear and non-linear components of the deformation process within an area of interest during the whole observation period. A high stability of the platform is required for a reliable estimation of the geodetic phenomena. Accordingly, space-borne SAR images are operatively employed for DInSAR estimation, air-borne DInSAR still constituting a challenging research issue. SARPolarimetry aims at charactering the illuminated area through the analysis of its response under different combinations of transmitting and receiving antennas polarization, called polarimetric channels. The Polarimetric SAR Interferometry joins the capability of Polarimetry to separate independent scattering mechanisms and the sensitivity of Interferometry to the corresponding phase centers' elevation, making it possible to describe the volumetric distribution of the scatterers within the observed area. Owing to the lack of long-time collections of polarimetric space-borne SAR data, the studies carried out in this research field have been mainly based on air-borne acquisitions. Yet, there is a great expectation for the improvements that polarimetry may bring to assessed single-polarization techniques such as the DinSAR.The research described in this PhD dissertation fills for the first time the gap between SAR Polarimetry and SAR Differential Interferometry through the employment of an X-band ground-based SAR (gbSAR) sensor developed by the Remote Sensing Lab of the Universitat Politècnica de Catalunya (UPC).The work is divided into two main blocks. The first part deals with the algorithms that have been developed to make the UPC system operative and its acquisitions easy to use. Summarily, they include the mathematical formulation of the sensor's working principles, the raw data processing chain and the polarimetric calibration method, the geocoding procedures, and the techniques compensating for the atmospheric artefacts affecting gbSAR zero-baseline acquisitions.The second part is concerned with demonstrating the benefits that polarimetric SAR measurements provide with respect to single-polarization data for differential applications. In order to cope with this task, the data sets acquired during a one-year measurement campaign carried out in the village of Sallent, northeastern Spain, are analyzed. The experiment was focused on monitoring the subsidence phenomenon affecting a district of the village with the UPC gbSAR sensor. Three main issues are here argued. The first one is the time non-stationary behaviors characterizing the urban environment at X-band in the gbSAR observation geometry. Their effects are analyzed in detail and a novel non-stationary filtering technique tailored to deterministic scatterers' properties is introduced to preserve the differential phase information. The second one is the compensation of the troposphere changes in long-time span gbSAR differential interferograms. A new technique is worked out to effectively separate the differential phase variations due to the atmospheric artefacts from the deformation components. The third one is the use of the whole polarimetric differential information. A novel polarimetric differential scattering model is put forward to relax the constraints of an advanced DInSAR technique, the Coherent Pixel Technique, and to propose an innovative polarimetric approach. The advantages offered by Polarimetric DInSAR are demonstrated in terms of quality of the deformation-rate map describing the subsidence phenomenon in Sallent. In the end, the potentials of coherence-optimization techniques for the further improvement of the deformation process estimation are stressed.

En las últimas décadas, ha habido un creciente interés en la determinación de algunos parámetros como la salinidad y altura de la superficie marina (SSS y SSH), o la humedad del suelo. Algunas de estas variables son determinantes a la hora de desarrollar nuevos modelos climáticos más precisos. La salinidad en la superficie marina por ejemplo, es uno de los factores más importantes en la generación de la circulación termohalina. En términos oceanográficos, se llama circulación termohalina a la circulación convectiva que afecta de modo global al conjunto de las masas de agua oceánicas. Este concepto tiene especial relevancia por su significativa participación en el flujo neto de calor desde las regiones tropicales hacia las polares, sin la que no se comprendería el clima terrestre. La circulación es debida a la diferencia de densidad que tiene el agua a diferentes temperaturas y salinidades, con las masas más densas tendiendo a hundirse y las menos densas a ascender. En el caso de las masas oceánicas, esta densidad depende de dos factores: la temperatura y la salinidad. La densidad decrece cuando aumenta la temperatura y crece con la salinidad. Por su parte, la salinidad está ligada a los efectos de la evaporación y las precipitaciones. Al entrar en contacto el aire caliente en las zonas tropicales con la superficie marina, éste produce que el agua se evapore, reduciendo su temperatura e incrementando la concentración salina. Las precipitaciones por su parte, reducen la concentración de sales en la superficie.La importancia que tiene la salinidad en la superficie marina ha hecho que sea necesario conocer su valor con cierta periodicidad y precisión. Gracias a la relación que hay entre la salinidad y la emisión electromagnética que se produce en la superficie marina, se han desarrollado algunas misiones basadas en sistemas de radiometría embarcados en satélites artificiales. Con el propósito de medir la SSS y la humedad del suelo surge, en 1998, la misión SMOS (Soil Moisture and Ocean Salinity) de la ESA (European Space Agency: Agencia Espacial Europea). Ésta se basa en un radiómetro interferométrico en banda L para la estimación de la temperatura de brillo de la superficie observada y, a partir de esta, poder recuperar la información deseada. Por su parte, el Departament de Teoria del Senyal y Comunicacions (TSC) de la Universitat Politècnica de Catalunya (UPC), trabaja desde 2003 en un proyecto muy ambicioso llamado PAU (Passive Advanced Unit for ocean monitoring). Dentro de este proyecto se trabaja con sistemas de medición híbridos formados por tres instrumentos:reflectómetro GNSS (Global Navigation Satellite Signal); radiómetro interferométrico; y radiómetro de infrarrojos. Este proyecto está dedicado al radiómetro interferométrico de uno de estos instrumentos: PAU-SA (Passive Advanced Unit – Synthetic Aperture), más concretamente al desarrollo de un interfaz que permita procesar los datos generados por el radiómetro. Por otro lado, parte del trabajo también ha consistido en apoyar la implementación física del instrumento mediante planos virtuales. Los dos primeros capítulos de este documento están dedicados a los principios teóricos de la radiometría y de los radiómetros interferométricos. En el tercer capítulo se ofrece una descripción global de PAU-SA, y más detallada de la parte dedicada al radiómetro interferométrico. En el capítulo 4 se describe el interfaz de PAU-SA, haciendo especial hincapié en la interacción que este ofrece al usuario. En los capítulos 5 y 6 se describe paso a paso el procedimiento que lleva a cabo el interfaz para realizar la simulación del procesado realizado en el instrumento, y de los algoritmos empleados en la calibración de sus errores. A continuación, el capítulo 7 está dedicado a mostrar algunos resultados obtenidos con el interfaz. Finalmente, en el capítulo 8 se muestran algunos de los estudios realizados para apoyar la implementación de PAU-SA.

La missió SMOS de l'Agència Europea de l'Espai (ESA) té com a objectiu mesurar la humitat del sòl i la salinitat dels oceans, paràmetres fonamentals per tal d'entendre el canvi climàtic global.MIRAS (Radiòmetre de microones generador d'imatges pel mètode de síntesi d'obertura) és un tipus d'instrument nou per a l'observació de la terra i és l'únic instrument de la missió SMOS. Consisteix en un agrupació aprimada (thinned array) en forma d'i grega amb 21 elements per braç. Amb aquesta tècnica s'aconsegueixen grans obertures sintètiques amb una massa relativament reduida.Aquesta nova tecnologia ha estat triada per a la missió SMOS, per tal d'acomplir els criteris de resolució espacial (30-50km) i de temps de revisita (3 dies). En el camp de la radioastronomia ja es fan servir instruments similars a MIRAS, però en aquest cas les fontsobservades tenen una mida angular reduïda (estrelles i galàxies). En el cas de MIRAS, la terra és una font extensa que cobreix pràcticament tot el camp de visió de MIRAS, de tal manera que les tècniques de calibració desenvolupades per a radioastronomia no sónvàlides per a la missió SMOS.Aquesta tesi es concentra principalment en comprovar experimentalment diferents tècniques de calibració i demostrar la capacitat de MIRAS per a generar imatges. La segona part està dedicada al mode polarimètric de MIRAS i a la capacitat d'aquest a millorar el rendiment de MIRAS. Aquest tesi es va iniciar l'any 2000 gràcies a una beca de dos anys (de l'estiu de 2000 a l'estiu de 2002) al centre ESTEC de l'Agència Europea de l'Espai als Països Baixos. Durant aquesta estada es van realitzar les primeres campanyes de mesura per tal de comprovar els mètodes de calibració i les capacitats de generar imatge de MIRAS. En aquests tests de validació d'imatge es va utilitzar un primer prototipus de MIRAS. La realització, planificació, preparació, execució i processament de les dades són part d'aquesta tesi. Aquelles campanyes van demostrar la capacitat dels mètodes de calibració indicant, a més en quina direcció calia continuar treballant per tal de refinar-los. També van demostrar la capacitat de MIRAS per a generar imatges,mitjançant la mesura de la seva resposta impulsional. En aquesta tesi se'n presenten els resultats més importants. Durant l'estada a ESTEC també es va realitzar treball teòric i simulacions sobre interferometria polarimètrica, contribuint d'aquesta manera a la formulació de la funció de visibilitat polarimètrica i a la definició del mode de funcionament polarimetric de MIRAS.La tesi es va continuar al Laboratori de Tecnologia Espacial (LST) de la Universitat Tecnològica de Hèlsinki (HUT) durant tres mesos (agost 2002 a octubre 2002) com a investigador convidat. Els coneixements adquirits prèviament van servir per a contribuir al desenvolupament de HUT-2D, el radiòmetre interferomètric aerotransportat de LST pensatcom a demostrador de la tecnologia emprada a MIRAS, confirmant els resultats obtinguts a les campanyes prèvies a ESTEC.El febrer de 2003 es va continuar la tesi a l'Institut d'Estudis Espacials de Catalunya (IEEC) amb un contracte de recerca del ministeri d'Educació i Ciència. Es va estudiar l'efecte dela rotació de Faraday a MIRAS. El resultat és una proposta de solució per a compensar-la fent servir el mode polarimètric de MIRAS. En el tram final de la tesi s'ha fet l'electrònica de control (EGSE) d'un demostrador aerotransportat de MIRAS (SAM), per a l'ESA. Aquest instrument permet fer ús del mètode de calibració per injecció de soroll a dues temperatures, que és un refinament dels anteriors mètodes de calibració dels prototipus de MIRAS. La tesi presenta resultats experimentals preliminars d'aquest mètode de calibració., The SMOS mission of the European Space Agency (scheduled 2007) is devoted to measure Soil Moisture and Ocean Salinity, which are key parameters on the understanding of global climate change. The single instrument of this mission is the MIRAS (Microwave Imaging Radiometer using Aperture Synthesis), a new kind of instrument devoted to Earth observation. It is a thinned Y-shaped array with 21 elements per arm. With this technique a large synthetic aperture antenna with relative low weight can be obtained. This novel technique has been selected for the SMOS mission in order to fulfil both criteria ground resolution (35-50km) and revisit time (3 days). Similar instruments to MIRAS have already been used for radio astronomy but in that case only sources with a narrow angular size (stars and galaxies) were observed. In the case of MIRAS, the Earth is an extended source of thermal radiation, which almost fills up the complete field of view of MIRAS. The consequence of it is that the calibration techniques developed for radio astronomy may not be used in the SMOS mission. This thesis is mainly focused to experimentally test several calibration techniques and to prove the imaging properties of MIRAS. A second part is devoted to the polarimetric mode of MIRAS and its capability to improve its performance. This thesis was started thanks to a two year grant (from summer 2000 to summer 2002) at the ESTEC centre of the European Space Agency in the Netherlands. During this time the first experimental campaigns aimed to test calibration methods and imaging capabilities of MIRAS were done. In these so called image validation tests a first MIRAS prototype was used. The planning, preparation, execution and data processing for different tests was done. The capability of the calibration methods was demonstrated, showing also in which direction further research should be undertaken in order to refine them. The imaging properties of MIRAS were also demonstrated with the measurement of its impulsional response. The most important results are presented here. At the ESTEC centre theoretical work and simulations on polarimetric interferometry have also been done. This research contributed to the formulation of the polarimetric visibility function and the definition of the polarimetric operation mode of MIRAS. After the two years stage at ESTEC, the thesis was continued at the Laboratory of Space Technology (LST) of the Helsinki University of Technology (HUT) for three months (August 2002 to October 2002), as an invited researcher. There the HUT-2D interferometric radiometer, an airborne demonstrator instrument for MIRAS, was being constructed. The experience gained in the previous campaigns was shared with the HUT-2D team and the calibration methods were tested in a different instrument, confirming the previous results. In February 2003 this thesis was continued at the Institut d'Estudis Espacials de Catalunya (IEEC) under a research contract of the Spanish ministry of research. There the effect of Faraday rotation on MIRAS was studied. A solution for compensating it was proposed, making use of the polarimteric operation mode of MIRAS. The thesis was continued at IEEC, designing and manufacturing the Electrical Ground Support Equipment (EGSE) of an airborne demonstrator of MIRAS, known as SAM (Small Airborne MIRAS). This work was done for ESA. This instrument implements the complete calibration scheme with two-level noise injection, which is arefinement of the calibration schemes used in previous MIRAS prototypes. Preliminary experimental results of this novel calibration technique are also presented in this thesis.

A coherence optimization method, which makes use of polarimetry to enhance the quality of the interferograms, has been experimentally tested under laboratory conditions in an anechoic chamber. The experiments have proved the remarkable contribution that this technique offers in two important applications: the improvement of digital elevation maps (DEM) generation and the estimation of the height of vegetation targets

SAR Interferometry is a useful tool which allows the generation of high-precision Digital Elevation Models of the Earth surface. The paper describes an operational scheme of an interferometric processor, applicable to airborne data, which takes into account the specific nature of such platforms: observation geometry, phase characteristics or motion instabilities.

Millimetre-wave radiometry of the earth's surface from Low Earth Orbit (LEO) with a resolution of a few km requires antenna apertures several metres across and sub-second scanning times. Fulfilling these requirements with a mechanically scanned real-aperture antenna presents formidable mechanical challenges. An attractive alternative described here is to use synthetic aperture techniques employing a sparse-array of antennas that trade the mechanical complexity of real-aperture imaging for the electrical complexity of synthetic aperture imaging. We present results of an ESA-sponsored study aimed at seeking the optimum technique for high performance synthetic aperture mm-wave radiometry from LEO.

In the last years two new kinds of microwave radiometers are being studied for Earth observation: aperture synthesis interferometric radiometers and polarimetric radiometers. The first ones are formed by an array of small antennas whose outputs are cross-correlated and then, properly processed to obtain a map of the apparent brightness temperature of the whole scene being imaged. One- and two-dimensional systems have been studied by some space agencies, e.g. ESTAR by NASA, and MIRAS by ESA, as a solution that avoids the implementation of large steerable antennas at low frequencies (L-band), while reaching a relatively high spatial resolution: about 20 - 30 Km. More recently preliminary studies of mm-wave systems have also been studied to improve the spatial resolution achieved by today's radiometers. On the other hand, polarimetric radiometers are formed by a dual-polarization antenna. The real and the imaginary parts of the complex cross-correlation computed from the H/V outputs leads to the third and fourth Stokes parameters of the incoming thermal radiation, which are basically related to roughness state of the surface being imaged. At present, a number of studies are being conducted to establish the relationship with the wind direction over the sea surface. The performance analysis of those systems requires the modeling of the apparent brightness temperature map of the Earth and/or sea surface that would be imaged at the microwave and the mm-wave frequencies, which is the object of this paper.

This paper presents a new method for receiver calibration of interferometric radiometers. It is based on the distributed noise injection mechanism and it consists of fully calibrating the baseline error terms of the central antennas (which share the same noise source) while keeping only separable error calibration for the distant ones. This improves the accuracy of the shortest baselines, which are the most significant ones due to the smoothness of the brightness temperature to measure. Simulations show that, compared to previously reported methods, the improvement on the radiometric resolution can be as high as 3.9. The robustness against frequency response mismatch between receivers is improved by a factor 2.9.

Ascending-descending orbit combination for DEM generation is very promising technique which can be used to fill in ome gaps in the DEMs caused by the geometric deformations or SAR images. The benefits from the combination over layover and foreshortening areas are evident thanks to the new data made available over these areas from the opposite pair. However, other areas in the image will also improve its quality because of the averaging between the ascending and the descending pass. This paper shows an ascending descending orbit combination using ERS data. Two ascending and descending DEMs have been calculated independently and a combined DEM has been obtained from them on a coherence basis. The obtained DEMs have been compared with a high accuracy DEM (2m height rms) available. Results show an error reduction in the combined DEM over the ascending and descending ones. Ascending-descending orbit combination SAR interferometry assessment (DEM).

La interferometría SAR es una técnica que mediante la combinación coherente de imágenes radar de alta resolución de la superficie terrestre permite obtener patrones de interferencia de fase, los interferogramas, directamente relacionados con la geometría de la escena (el relieve). Un tratamiento posterior que involucra procesos críticos como un desenrollado de fase bidimensional y una georreferenciación considerando las efemérides del satélite y un modelo preciso de la superficie terrestre (datum) permite obtener - con algunas restricciones - un modelo digital del elevaciones del terreno (DEM) con precisiones en altura del orden de 10 m rms. Un segundo grupo de aplicaciones es la medida de pequeños movimientos de la superficie terrestre con una precisión por debajo del centímetro; estas aplicaciones diferenciales son las que han permitido estudiar el efecto de la atmósfera en los interferogramas SAR. En el artículo se muestran resultados obtenidos a partir de imágenes ERS-1 y ERS-2 de Tarragona.

La tesis contiene en primer lugar un estudio de las técnicas de interferometria radiometrica, con énfasis en las causas de error y su impacto en las características del sensor. A continuación se proponen y comparan varias técnicas de calibracion basadas en la inyección de ruido.Un aspecto notable de la tesis consiste en el desarrollo de técnicas de reconstrucción de la imagen radiometrica adaptadas a la geometría del sensor miras propuesto por la agencia espacial europea (esa).La tesis incluye tambien el diseño de un prototipo a escala reducida de radiometro interferometrico que se ha utilizado para verificar los resultados teóricos y simulados.En resumen se trata de un trabajo muy completo y riguroso, con numerosas aportaciones originales, que han sido contrastadas experimentalmente.

SAR Interferometry allows the obtention of digital elevation models (DEM) by combination of two synthetic aperture radar images acquired from slightly different viewpoints. ERS-1 SAR interferometry has already been validated over small areas. When processing wider areas, new adaptative filtering algorithms such as the short time Fourier transform are required. However, phase unwrapping is still the critical step. LMS an weighted LMS are two phase unwrapping algorithms which overcome some disadvantages of traditional residue based methods. Some results are shown obtained from ERS-1 images from Tarragona.

When computing the radiometric resolution of an interferometric radiometer the correlation among the errors of different baselines is usually assumed negligible. ln this way: a) the radiometric sensitivity turns out to be pixel independent (except for antenna pattern effects), and b) the error of the average of P redundant baselines is reduced by a factor of (P)1/2. While this may be the case in radioastronomy applications, for an on-board instrument where all the baselines are measured at the same time interval the errors will actually be correlated. This has two effects: a) The radiometric resolution changes from pixel to pixel and b) the radiometric resolution improvement introduced by redundance is reduced as compared with the case of independent errors. In this paper this correlation is computed and the results obtained are applied, first, to a fully redundant (all possible baselines are actually measured) filled linear array to analyze the actual radiometric improvement, and, next, to the same array without redundance to investigate the dependence of sensitivity on pixel information.

This paper is concerned with the radiometric sensitivity computation of an aperture synthesis interferometric radiometer devoted to Earth observation. The impact of system parameters and the use of simultaneous redundant measurements are analyzed. The interferometric radiometer uncertainty principle is presented; it quantifies the relationship between radiometric sensitivity and angular resolution.

An improved technique for generation of Digital Elevation Models (DEM), capable of dealing with full scene images (100x100 km) coming from an interferogram obtained with ERS satellite data is presented. Starting from an interferometric processor aimed to the geocoding of smaller areas, now we show the new improvements based on the use of a direct geocoding algorithm and Ground Control Points (GCP), in order to calibrate some imprecisions which appear in the case of very wide swaths. The direct geocoding algorithm is based on the transformation of phases directly into heights over a UTM grid, without an intermediate transformation of phases into heights in slant range. This technique provides more accurate results. A generated DEM of the test zone of Tarragona (Spain) and its error assessment are presented. Introduction A critical step in the interferometric process [3] is the transformation of unwrapped phases into geocoded heights. Several imprecisions in orbit generation, timing knowledge and geocoding can lead to significant height errors when we are working with wide areas. It is easy to observe false height slopes along the image during the process due to this imprecisions [1]. On the other hand, if we work with small areas these errors are more difficult to observe because their propagation is not so critical. Our goal in this paper is to present some techniques developed by our research group to obtain high quality DEM's (Digital Elevation Map) of small or wide images. Direct geocoding for generation of precise wide-area elevation models with ERS SAR data.

The interferometric techniques allow the generation of digital elevation models (DEM) from data collected by synthetic aperture radars (SAR). In this paper a geocoding method applied to ERS-1/2 data is proposed. It is based on an exact knowledge of the orbits, a step from phase to height in slantrange and, finally, a projection and interpolation to generate a final map in UTM coordinates. Next, a technique evaluated in the airborne case is also presented. It is able to relate directly the interferometric phase of every point of the image to its position in a global reference system.

Improved weather forecast and climate monitoring rely on a better quantification of soil moisture (SM) and sea surface salinity (SSS). The most accurate way to measure them from remote sensors is by using radiometers at L band, where the sensitivity of the brightness temperature is maximum and the atmosphere is almost transparent. In order to provide a global coverage of these basic parameters within a revisit time of 3 days and 30-50 Km spatial resolution, the SMOS mission was recently selected by ESA in the frame of the Earth Explorer Opportunity Missions. The sensor being considered for this mission (called MIRAS) uses the concept of 2D interferometric radiometrey, and is scheduled to be launched in 2005. A demonstrator consisting of a number of receivers is now under development by CASA (E) by contract with ESA. This work presents the block diagram of a single receiver chain in the SMOS instrument and its main requirements in terms of mission tradeoffs.

Study the possibilities of deploying SAR sensors in space using small satellites. This work focuses on the analysis of X-band Interferometric Synthetic Aperture Radar (InSAR) satellite acquisitions over forested areas in Estonia with the main goal of estimating forest tree height. The objective is to understand the behavior of InSAR coherence better particularly in the forest media and seek for suitable models to derive forest height (can be further linked to forest above ground biomass l) from InSAR measurements. The test area is located in Estonia, in the natural park of Soomaa. A set of 9 InSAR image pairs acquired by the German TanDEM-X satellite mission during 2012 are used in the study. The interferometric SAR processing has been done with SNAP (Sentinel Application Platform), a software designed by ESA (European Space Agency) for Sentinel and third-party missions. The focus is set on Random Volume over Ground (RVoG) and related models to describe the relation between forest parameters and InSAR coherence. In order to derive tree height from the models, complex domain inversion procedure is developed. The inversion results are compared with simplified model inversion and validated with airborne laser scanning data acquired by the Estonian Land Board. The results show robustness of Random Volume over Ground model for modelling the X-band complex coherence over forested areas. Developed tree height retrieval procedure shows an error between 26.7\% (RMSE = 3.8 m) and 30.2 \% (RMSE = 4.3 m) on a pixel-by-pixel basis.