Dissertations / Theses on the topic 'Optic Remote Sensing'

Recent progress in reducing the extrinsic losses of fluorozirconate optical fibers has increased the material research efforts for these new waveguides. Fluorozirconate fibers, which are inherently more transparent than silica fibers, are predicted to have intrinsic losses as low as 0.001 dB/km at 3.45 μm [11]. Unfortunately, high intrinsic losses still plague these new optical fibers and these losses must be understood before ultra-low loss fibers become a reality. An automated fiber optic characterizer can help determine the loss mechanisms and the optical properties of fluorozirconate fibers so extrinsic loss mechanisms can be understood and eventually controlled. The automated fiber optic characterizer can also speed up the measurement process by using a microcomputer to align the fiber, calculate the results, and plot the graph. This thesis presents the technical issues involved in the design and construction of an automated infrared fiber optic characterizer. The thesis also outlines the test results of a constructed automated fiber optic characterizer. The characterizer measures spectral attenuation between 0.8 μm and 4 μm, differential modal attenuation between 1.6 μm and 4 μm, and numerical aperture at 1.55 μm and 2.55 μm.
Master of Science

Au-delà de leur rôle d’icône du changement climatique, les glaciers de montagne sont une composante essentielle de notre planète. Ils sont, de plus, de véritables « climat-mètres » naturels. Malgré leur faible superficie (0.5% des terres émergées), les glaciers de montagne contribuent à hauteur de 30% à la hausse du niveau des mers. Dans certaines régions, ils constituent de véritables enjeux quant à l’eau potable, l’agriculture, la production hydroélectrique ou les aléas glaciaires. Peu sont en revanche instrumentés (<0.0025%) et leurs fluctuations à l’échelle de régions entières sont mal connues.Grâce au développement de capteurs satellitaires à haute résolution spatiale (métrique à décamétrique), le développement de méthodes automatisées permet aujourd’hui d’augmenter considérablement le nombre de glaciers observés. Après avoir dressé un état de l’art des méthodes existantes et identifié les verrous méthodologiques, nous avons développé deux méthodes en particulier.La première se base sur la détection automatique de l’altitude de la limite glace/neige (i.e. ligne de neige) à la surface du glacier, à partir d’images satellites optiques. Cette altitude, lorsque mesurée à la fin de l’été, est un marqueur du changement de masse à la surface du glacier ayant eu lieu au cours de l’année (appelé bilan de masse de surface). Cette approche nous a permis d’estimer le bilan de masse de surface annuel de 239 glaciers dans les Alpes européennes et de 82 glaciers dans les Andes tropicales pour la période 2000-2016 et 2000-2018, respectivement. La perte moyenne annuelle observée est de -0.74 et de -1.29 m équivalent eau par an pour les deux régions respectivement. A notre connaissance, cette approche a permis d’établir le premier jeu de données de bilans de masse de surface annuels pour des glaciers individuels à échelle régionale à partir d’images satellites optiques. Une dépendance du bilan de masse de surface moyen par glacier à des caractères morpho-topographiques (e.g. pente, altitude médiane …) a été observée, où plus les glaciers sont pentus et hauts en altitude, moins leur perte de masse est importante. Une comparaison avec des mesures in situ dans les Alpes Européennes révèle une surestimation de la perte de masse par ces dernières si on les extrapole spatialement, notamment à cause de la faible représentation de glaciers à forte pente (>20°) dans les mesures in situ. Notre étude sur les Alpes Européennes a de plus permis d’identifier une variabilité interannuelle hétérogène sur cette région, en partie expliquée par des contextes climatiques différents grâce à l’utilisation de données issues de ré-analyses.Le développement d’une autre méthode a permis, à partir de l’analyse de carte d’albédo issues du capteur MODIS, de caractériser le bilan de masse de surface annuel et estival de 30 glaciers dans les Alpes françaises. Cette étude ouvre la porte à l’utilisation de cette méthode pour l’analyse du bilan annuel et saisonnier à l’échelle régionale.Ce travail a permis, à travers des applications dans différentes régions englacées, de développer et valider des méthodes capables, à partir d’images satellites optiques, d’estimer le bilan de masse de surface annuel et saisonnier de glaciers de montagne à l’échelle de régions entières. Ces estimations peuvent ensuite être utilisées pour : (1) étudier l’impact du climat local sur les glaciers de montagne ; (2) d’investiguer de possibles conditions météorologiques favorisant les fluctuations observées ; (3) calibrer et valider les modèles glacio-hydrologiques utilisés pour estimer les contributions actuelles et futures des glaciers de montagne au fonctionnement hydrologique des bassins versants et à l'élévation du niveau des mers
Beyond their iconic role of climate change, mountain glaciers can be considered as Earth’ essential component and natural “climate-meter”. Despite their small spatial coverage (0.5% of emerged land), mountain glaciers contribute as high as 30% of the observed sea-level rise. In some regions, they are considered as essential issues because of their importance in terms of potable water, agriculture, hydroelectricity or natural hazards. A small share is however monitored in situ (<0.0025%) and their fluctuations at regional scale are poorly known.Thanks to the development of high spatial resolution satellite sensors (metric to decametric), new methods are today available to significantly increase the number of monitored glaciers. After a state of the art of the existing methods and an identification of the limitations, we focused our attention on the development of two methods.The first one is based on the automatic detection of the snow/ice interface altitude (i.e. snowline) at the glacier surface from optical satellite images. This altitude, when estimated at the end of summer, is a proxy of the annual glacier-wide mass change at the glacier surface (called surface mass balance, SMB). Using this approach, we estimated the annual SMBs of 239 glaciers in the European Alps and 82 glaciers in the tropical Andes for the period 2000-2016 and 2000-2018, respectively. The mean mass loss are -0.74 and -1.29 m water equivalent per year for the two regions, respectively. This approach allowed to derive the first dataset of annual SMBs for individual glaciers at regional scale from optical remote sensing. We found significant relationships between the computed SMBs and the glacier morpho-topographic features (e.g. slope, median altitude, …), with steeper and higher glaciers, experiencing less mass losses. Comparison with in situ monitored SMBs revealed an overestimation of mass losses from in situ estimates, due to a low representativeness of steep glaciers (>20°) in the in situ datasets. Our study also revealed heterogeneous inter-annual variability across the European Alps, partially explained by the climatic context of the studied sub-regions, thanks to the analysis of climate reanalysis data.We developed a second method to derive the annual and summer SMBs from albedo maps, computed from MODIS images. With an application on 30 glaciers in the French Alps, this work opened the way toward a regional application of this method, in order to estimate both annual and summer SMBs.By performing regional applications on different glacierized regions, we developed and validated methods capable of deriving the annual and summer SMBs of individual mountain glaciers at regional scale, from optical remote sensing data. These data could then be used to (1) assess the impact of peculiar climatic conditions onto mountain glaciers; (2) investigate possible meteorological conditions driving the documented glacier fluctuations; (3) calibrate and validate glacio-hydrological models used to estimate the current and future contributions of mountain glaciers to the hydrological functioning of mountain catchments and to sea level rise

L'agriculture en Tunisie fait partie des secteurs importants sur lesquels reposent l'économie du pays. Elle revêt également son importance par sa contribution à la sécurité alimentaire. Dans un contexte de gestion des ressources naturelles, la caractérisation et le suivi des états de surface est indispensable, particulièrement dans les régions semi-arides où plusieurs contraintes freinent le développement agricole (période de sécheresse, conflits sur le partage des eaux, manque de ressources, surexploitations des nappes, etc.). En Tunisie, près de 80 % des ressources en eau disponibles sont utilisées par l'agriculture avec une efficacité limitée. Là, où les ressources en eau sont très limitées, l'estimation de l'état hydrique de surface est particulièrement nécessaire pour établir les décisions adéquates pour une meilleure gestion de cette ressource. Dans ce contexte, la télédétection fournit une base fondamentale de données pour l'observation de la surface et constitue un outil majeur pour l'acquisition d'informations à distance. Les travaux réalisés au cours de cette thèse sur la plaine de Kairouan, au Centre de la Tunisie et caractérisée par un climat semi aride, contribuent à l'évaluation du potentiel des nouveaux capteurs satellitaires Sentinel-1 (S-1) et Sentinel-2 (S-2) pour la caractérisation des états de surface, spécifiquement l'humidité du sol dans un contexte de gestion durable des ressources en eau et en sol. En effet, ces nouveaux systèmes offrent aujourd'hui des produits opérationnels avec une forte répétitivité temporelle et des résolutions spatiales métriques permettant un suivi régulier. Dans notre contexte, les données radars sont particulièrement sensibles aux conditions de surface, précisément à l'humidité du sol, à la rugosité de surface et à la végétation. Ils se dévoilent comme les outils les plus prometteurs pour un suivi précis à l'échelle de la parcelle ou régionale. Ce travail comprend deux principales parties qui relient directement l'humidité du sol (variable clé pour différents processus) à l'irrigation dans un premier temps, puis à la texture du sol. L'approche adoptée combine les mesures expérimentales à l'utilisation de données de la télédétection multi-capteurs en synergie, ainsi à la modélisation et à la cartographie. La thèse se structure en trois volets. Le premier volet de ce travail évalue le potentiel des données radars en bande C pour une large base de données. Les résultats ont montré à travers des études du comportement et de modélisation que le signal radar permet de suivre la dynamique temporelle et spatiale de l'humidité du sol sur des parcelles de céréales. Le second volet, consiste à évaluer l'utilisation conjointe de données optiques et radars afin de pouvoir prédire l'état hydrique de surface sur une couverture végétale.[...]
Agriculture is considered as one of the most important sectors in Tunisia on which the country's economy is predominately based. It is also important because of its contribution to food security. In the context of natural resource management, the characterization and monitoring of surface states is essential, particularly in semi-arid regions where several constraints hamper agricultural development (period of drought, conflicts over water sharing, lack of resources, overpumping of groundwater, etc.). In Tunisia, nearly 80% of available water resources are used by agriculture with limited efficiency. Here, with very limited water resources, the estimation of the surface water state is necessary to establish the appropriate decisions for a better sustainable management. In this context, remote sensing provides a fundamental database for surface observation. It is a major tool for remote sensing data acquisition.The work carried out during this thesis contributes to evaluate the potential of the new Sentinel-1 (S-1) and Sentinel-2 (S-2) satellite for the characterization of surface states, specifically soil moisture in a context of sustainable management of water and soil resources. Indeed, these new systems offer operational products with a high temporal repeatability and metric spatial resolutions allowing regular monitoring. In our context, radar data is particularly sensitive to surface conditions, specifically soil moisture, surface roughness and vegetation cover. They are unveiled as the most promising tools for accurate monitoring at the field or regional scale. This work includes two main parts that directly relate soil moisture (key variable for different processes) to irrigation first, and then to soil texture. The approach adopted combines experimental measurements with the use of different remote sensing data in synergy, modeling and mapping. The thesis is structured in three parts. The first part of this work evaluates the potential of C-band radar data for a large database. The results showed through behavioral and modeling studies that the radar signal could retrieve temporal and spatial dynamics of soil moisture on cereal plots. The second component consists of evaluating the combined use of optical and radar data in order to predict surface water conditions over vegetative cover. With a precision of about 6 vol. %, soil moisture mapping is then proposed at high spatial resolution, by inverting the Water Cloud Model (WCM), a backscattering model for vegetation cover.[...]

This paper describes the development, characterization, and modeling of a Tunable Filter Camera (TFC). The TFC is a new multispectral instrument with electronically tuned spectral filtering and low-light-level sensitivity. It represents a hybrid between hyperspectral and multispectral imaging spectrometers that incorporates advantages from each, addressing issues such as complexity, cost, lack of sensitivity, and adaptability. These capabilities allow the TFC to be applied to low-altitude video surveillance for real-time spectral and spatial target detection and image exploitation. Described herein are the theory and principles of operation for the TFC, which includes a liquid crystal tunable filter, an intensified CCD, and a custom apochromatic lens. The results of proof-of-concept testing, and characterization of two prototype cameras are included, along with a summary of the design analyses for the development of a multiple-channel system. A significant result of this effort was the creation of a system-level model, which was used to facilitate development and predict performance. It includes models for the liquid crystal tunable filter and intensified CCD. Such modeling was necessary in the design of the system and is useful for evaluation of the system in remote-sensing applications. Also presented are characterization data from component testing, which included quantitative results for linearity, signal to noise ratio (SNR), linearity, and radiometric response. These data were used to help refine and validate the model. For a pre-defined source, the spatial and spectral response, and the noise of the camera, system can now be predicted. The innovation that sets this development apart is the fact that this instrument has been designed for integrated, multi-channel operation for the express purpose of real-time detection/identification in low-light-level conditions. Many of the requirements for the TFC were derived from this mission. In order to provide background for the design requirements for the TFC development, the mission and principles of operation behind the multi-channel system will be reviewed. Given the combination of the flexibility, simplicity, and sensitivity, the TFC and its multiple-channel extension can play a significant role in the next generation of remote-sensing instruments.

A common method to identify or model the dominant directional reflective properties of a surface is the bidirectional reflectance distribution function (BRDF). BRDF describes the angular behavior by which light interacts with surfaces. Remote sensing technology has advanced to the stage where hyperspectral sensors, with hundreds of separate wavelength bands, are fairly common. This necessitates examining BRDF in the hyperspectral regime, which implies examining the directional reflective properties of hundreds of narrowly spaced wavelength bands.

In this dissertation I hypothesize that beach sand BRDF is wavelength dependent. Principal component analysis (PCA) and correlation matrix analysis of in situ measurements were used to test whether the spectral variability in the visible, near-infrared and shortwave directional reflectance factor of beach sands with and without freshwater surface films are wavelength dependent. The hyperspectral BRDF of beach sands exhibit weak spectral variability, the majority of which can be described with three to four broad spectral bands. These occur in the absence of a water layer on top of the sand in three wavelength ranges of 350-450 nm, 700-1350 nm, and 1450-2400 nm. When observing sheet flow on sand, a thin layer of water enhances reflectance in the specular direction at all wavelengths, and that spectral variability may be described using four spectral band regions of 350-450 nm, 500-950 nm, 950-1350 nm, and 1450-2400 nm. Spectral variations are more evident in sand surfaces of greater visual roughness than in smooth surfaces, regardless of sheetflow.

Research has been done for the calibration of a thermal infrared imaging system for the measurement of transmission line conductor sample emissivities. The spectral response of the imaging system was from 8 to 12 micrometers. A laboratory set-up was designed and built for this analysis. The laboratory equipment consisted of a FLIR 1000a thermal infrared imaging system, a stainless steel black-body source with dual emissivity front surface coatings, an Elexor Industries PL1000 data acquisition and control system, and an IBM personal computer AT with imaging board and imaging software. The emissivities of the conductor samples were obtained through the analysis of thermal infrared images of each conductor with a blackbody cavity and low emissivity source simultaneously imaged as references. This analysis gave statistical mean grey levels for each conductor sample and references. From these mean grey levels the emissivity of the conductor samples were computed. Nine transmission line conductor sample emissivities where measured to an average accuracy of 17.5%. The emissivities ranged from .451 to .959.

Recent efforts in Earth remote sensing have focused on accurately measuring top-of-atmosphere and surface leaving radiances. One factor that must be accounted for in the radiometric calibration of an Earth remote sensing satellite is the polarization of the radiance. This dissertation provides a comprehensive analysis of how polarization has an impact on the radiometric calibration of visible through long wave infrared Earth remote sensing satellites (0.4 through ∼15 μm). The first part of this dissertation concentrates on reviewing the current status of calibration and of polarization measurements in Earth remote sensing. It provides a comprehensive review of polarization in Earth scenes, calibration targets, and the sensitivity of instruments. The second part examines how polarization affects calibration during the application of the calibration coefficients. One must account for the differences in polarization between the calibration target, used to determine the calibration coefficients, and the scene itself. This dissertation derives the impact of polarization on the radiometric calibration coefficients using both the Stokes vector and the Jones vector formalisms and accounts for the instrument polarization sensitivity, calibration target polarization, and scene polarization through normalization. Using these derived results, the impacts of polarization on radiometric uncertainty are calculated for the family of theoretical cases and for cases based on literature data. The third part of this dissertation examines how the polarization response of an instrument can affect the calibration by creating a variation in the response vs. scan angle (RVS). It derives the mathematical relationship between the polarization response of an instrument and its response vs. scan angle. It examines the correlation between the two using MODIS pre-launch system level polarization and RVS measurement data and derives the sensitivity of the RVS to aft optics polarization. This establishes when scan mirror data is sufficient to characterize RVS and when a system level measurement is required. This dissertation then examines potential ways to determine the instrument's polarization response and response vs. scan angle post-launch. Finally, this dissertation identifies sensitivity thresholds in both cases and summarizes when polarization should be accounted for in radiometric calibration. Potential areas for future advancement of the field are discussed.

Carbon Dioxide (CO 2) is a known contributor to the green house gas effect. Emissions of CO 2 are rising as the global demand for inexpensive energy is placated through the consumption and combustion of fossil fuels. Carbon capture and sequestration (CCS) may provide a method to prevent CO 2 from being exhausted to the atmosphere. The carbon may be captured after fossil fuel combustion in a power plant and then stored in a long term facility such as a deep geologic feature. The ability to verify the integrity of carbon storage at a location is key to the success of all CCS projects. A laser-based instrument has been built and tested at Montana State University (MSU) to measure CO 2 concentrations above a carbon storage location. The CO 2 Detection by Differential Absorption (CODDA) Instrument uses a temperature-tunable distributed feedback (DFB) laser diode that is capable of accessing a spectral region, 2.0027 to 2.0042 microns, that contains three CO 2 absorption lines and a water vapor absorption line. This instrument laser is aimed over an open-air, two-way path of about 100 m, allowing measurements of CO 2 concentrations to be made directly above a carbon dioxide release test site. The performance of the instrument for carbon sequestration site monitoring is studied using a newly developed CO 2 controlled release facility. The field and CO 2 releases are managed by the Zero Emissions Research Technology (ZERT) group at MSU. Two test injections were carried out through vertical wells simulating seepage up well paths. Three test injections were done as CO 2 escaped up through a slotted horizontal pipe simulating seepage up through geologic fault zones. The results from these 5 separate controlled release experiments over the course of three summers show that the CODDA Instrument is clearly capable of verifying the integrity of full-scale CO 2 storage operations.

This dissertation describes the design, construction, and calibration of a portable short wave infrared (SWIR) spectroradiometer. The main use for the instrument is the collection of ground reflectance and radiance data for the radiometric calibration of operational and proposed high spectral resolution remote-sensing systems, such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS), the Moderate Resolution Imaging Spectroradiometer (MODIS), the High Resolution Imaging Spectrometer (HIRIS), and the Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER). The instrument will also be used for cross calibrating Earth Observing System (EOS) calibration facilities and for a variety of high spectral resolution studies in earth science. The instrument is designed to be carried as a backpack unit, on a vehicle, or in a helicopter or airplane. The spectroradiometer covers the range from 1.05 to 2.45 μm. The spectral sampling interval is 1.37 nm and the spectral resolution is variable from about 5 nm to more than 100 nm. A single spectrum can be acquired in as little as 1 s. The signal-to-noise ratio (SNR) for a single 1-s scan is about 90 at a wavelength of 2.2 μm for a lambertian surface of 100% reflectance illuminated by the sun at normal incidence with 14-nm spectral resolution, a 25° background temperature, and no atmospheric attenuation. The SNR can be improved by averaging multiple scans. Field-of-view defining optics are coupled by a flexible fiber optics bundle to the spectroradiometer, which consists of a non-scanning concave holographic diffraction grating with flat focal field imaged onto a 1024-element liquid-nitrogen-cooled PtSi linear-array detector. The combination of concave grating and linear-array detector was chosen in preference to Fourier transform, Hadamard transform, and scanned grating monochromator systems on the basis of simplicity, high SNR, and greatest radiometric accuracy.

Previous research in the US Virgin Islands (USVI) has demonstrated that land-based sources of pollution associated with watershed development and climate change are local and global factors causing coral reef degradation. A good indicator that can be used to assess stress on these environments is the water quality. Conventional assessment methods based on in situ measurements are timely and costly. Satellite remote sensing techniques offer better spatial coverage and temporal resolution to accurately characterize the dynamic nature of water quality parameters by applying bio-optical models. Chlorophyll-a, suspended sediments (TSM), and colored-dissolved organic matter are color-producing agents (CPAs) that define the water quality and can be measured remotely. However, the interference of multiple optically active constituents that characterize the water column as well as reflectance from the bottom poses a challenge in shallow coastal environments in USVI. In this study, field and laboratory based data were collected from sites on St. Thomas and St. John to characterize the CPAs and bottom reflectance of substrates. Results indicate that the optical properties of these waters are a function of multiple CPAs with chlorophyll-a values ranging from 0.10 to 2.35 ?g/L and TSM values from 8.97 to 15.7 mg/L. These data were combined with in situ hyperspectral radiometric and Landsat OLI satellite data to develop a regionally tiered model that can predict CPA concentrations using traditional band ratio and multivariate approaches. Band ratio models for the hyperspectral dataset (R² = 0.35; RMSE = 0.10 ?g/L) and Landsat OLI dataset (R² = 0.35; RMSE = 0.12 ?g/L) indicated promising accuracy. However, a stronger model was developed using a multivariate, partial least squares regression to identify wavelengths that are more sensitive to chlorophyll-a (R² = 0.62, RMSE = 0.08 ?g/L) and TSM (R² = 0.55). This approach takes advantage of the full spectrum of hyperspectral data, thus providing a more robust predictive model. Models developed in this study will significantly improve near-real time and long-term water quality monitoring in USVI and will provide insight to factors contributing to coral reef decline.

This thesis investigated the science behind polarimetric road ice detection systems. Laboratory Mueller matrix measurements of a simulated road under differing surface conditions were collected searching for a discriminatory polarization property. These Mueller matrices were decomposed into depolarization, diattenuation, and retardance. Individual sample surface polarization properties were then calculated from these three unique matrices and compared. Specular and off-specular reflection responses of each sample were collected. Four polarization properties stood out for having high separation between dry and iced measurements: Depolarization Index, Linear Diattenuation, Linear Polarizance, and Linear Retardance.

Through our investigation polarimetric ice detection is possible. Continued research of the polarization properties of road ice can result in the development of a road ice detection system. Proposed deployment methods of such a system have been outlined following the analysis of the data collected in this experiment.

For decades, traditional remote sensing retrieval methods that rely solely on the spectral intensity of the water-leaving light have provided indicators of aquatic ecosystem health. With the increasing demand for new water quality indicators and improved accuracy of existing ones, the limits of traditional remote sensing approaches are becoming apparent. Use of the additional information intrinsic to the polarization state of light is therefore receiving more attention. One of the major challenges inherent in any above-surface determination of the water-leaving radiance, scalar or vector, is the removal of extraneous light which has not interacted with the water body and is therefore not useful for remote sensing of the water itself. Due in-part to the lack of a proven alternative, existing polarimeter installations have thus far assumed that such light was reflected by a flat sea surface, which can lead to large inaccuracies in the water-leaving polarization signal. This dissertation rigorously determines the full Mueller matrices for both surface-reflected skylight and upwardly transmitted light by a wind-driven ocean surface. A Monte Carlo code models the surface in 3D and performs polarized ray-tracing, while a vector radiative transfer (VRT) simulation generates polarized light distributions from which the initial Stokes vector for each ray is inferred. Matrices are computed for the observable range of surface wind speeds, viewing and solar geometries, and atmospheric aerosol loads. Radiometer field-of-view effects are also assessed. Validation of the results is achieved using comprehensive VRT simulations of the atmosphere-ocean system based on several oceanographic research cruises and specially designed polarimeters developed by the City College of New York: one submerged beneath the surface and one mounted on a research vessel. When available, additional comparisons are made at 9 km altitude with the NASA Research Scanning Polarimeter (RSP). Excellent agreement is achieved between all instrumentation, demonstrating the accuracy of the modeling approach and validating the computed Mueller matrices. Further, the results are used to demonstrate the feasibility for polarimetric retrieval of the total attenuation coefficient for Case II waters, a feat which is not possible using scalar remote sensing methods.

Earth observation satellites cover large areas with frequent temporal repetition and provide us with new insight into ocean and coastal processes. Ocean colour measurements from satellite remote sensing are linked to the bio-optics, which refers to the light interactions with living organisms and dissolved and suspended constituents in the aquatic environment. Human pressures have changed the aquatic ecosystems, by, for example, the increased input of nutrient and organic matter leading to eutrophication. This thesis aims to study and develop the link between bio-optical data and the remote sensing method to the monitoring and management of the Baltic Sea. The results are applied to the European Union’s Water Directives, and the Baltic Sea Action Plan from the Helsinki commission. In paper I indicators for eutrophication, chlorophyll-a concentration and Secchi depth were evaluated as a link to remote sensing observations. Chlorophyll-a measurements from an operational satellite service (paper I) were compared to conventional ship-based monitoring in paper II and showed high correlations to the in situ data. The results in paper I, II and IV show that the use of remote sensing can improve both the spatial and temporal monitoring of water quality. The number of observations increased when also using satellite data, thus facilitating the assessment of the ecological and environmental status within the European Union’s water directives. The spatial patterns make it possible to study the changes of e.g. algae blooms and terrestrial input on larger scales. Furthermore, the water quality products from satellites can offer a more holistic and easily accessible view of the information to decision makers and end-users. In paper III variable relationships between in situ bio-optical parameters, such as coloured dissolved organic matter (CDOM), dissolved organic carbon, salinity and Secchi depth, were found in different parts of the Baltic Sea. In paper IV an in situ empirical model to retrieve suspended particulate matter (SPM) from turbidity was developed and applied to remote sensing data. The use of Secchi depth as an indicator for eutrophication linked to the concentrations of chlorophyll-a and SPM and CDOM absorption was investigated in paper V. The variations in Secchi depth were affected differently by the mentioned parameters in the different regions. Therefore, one must also consider those when evaluating changes in Secchi depth and for setting target levels for water bodies. This thesis shows good examples on the benefits of incorporating bio-optical and remote sensing data to a higher extent within monitoring and management of the Baltic Sea.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.

As attenuation in silica based fibers approaches its ultimate theoretical limit, investigation is in progress to develop new materials which exhibit lower losses than silica. These bulk materials could then be used to fabricate ultralow loss optical fibers which operate farther out in the infrared than do silica fibers. Such infrared fibers could be used in long, repeaterless telecommunications links, the transmission of CO and CO₂ laser power, and in several sensing mechanisms. This thesis presents an overview of these new fibers and how they can be applied in noncontact temperature measurement. Fiber optic temperature sensing is thus reviewed, and an optical fiber pyrometer is discussed.

Master of Science

The absolute calibration of remote sensing systems is based upon radiometric standards. The irradiance standards are currently 1000-watt quartz tungsten-halogen lamps that are traced to National Institute of Standards and Technology standards by a middle party at a significant cost. Lamp instability, short lifetime and calibration inaccuracy present problems. A detector-based absolute calibration technique is described here to replace the lamp calibration in the visible portion of the spectrum (approximately 400 to 700 nm). The system utilizes a quantum efficient QED-200 trap detector in an automated facility to absolutely characterize lamp spectral irradiances or reflectance panel spectral radiances. The measured irradiance of a directly-viewed standard lamp compared favorably (within 0.8%) to the original calibration. Standard-reflectance-panel radiance measurements could not be accurately compared (within 5%) to the illuminating standard lamp irradiance because of excessive stray light in the calibration facility.

As the field of remote sensing continues to grow with the launches of many new and complex satellite sensors in the next year, the ability to provide absolute calibration of these sensors becomes paramount for the many environmental studies proposed. In particular, temporal studies that monitor global changes in atmospheric constituents, ocean and terrestrial temperatures, and vegetation require that changes in the sensor itself, over the period of the study, be understood so that the data may be corrected. Numerous studies have established that satellite sensors change in orbit with respect to preflight calibration, in some cases, up to 20% or more over periods of three years. This research describes the development of an improved cross-calibration method of on-orbit satellite sensor radiometric calibration. The objective of the cross-calibration method is to transfer one sensor's calibration to another sensor which is typically difficult or expensive to calibrate with other methods. The cross-calibration method is relatively inexpensive to apply, and therefore there was a strong incentive to improve the application of the method and the understanding of the uncertainties associated with the method. The primary effort in this work has been the development of a cross-calibration software program which provides the means to easily perform end-to-end cross-calibrations. The program allows for a multiplicity of sites to be run, provides a search mechanism in order to identify calibration sites with particular characteristics, and contains an extensive error analysis capability. As part of this work, a search for acceptable cross-calibration sites was also performed which would allow a reduction in uncertainties of the method. Calibrations of five different sensor band pairs using System Pour l'Observation de la Terre (SPOT) 3, Landsat Thematic Mapper, and Advanced Very High Resolution Radiometer (AVHRR) sensors are performed. Very good results are obtained when the results are compared with other more expensive calibration methods, and the calibrations yielded uncertainties lower than reported in previous work.

Carbon dioxide (CO 2) is a known greenhouse gas. Due to the burning of fossil fuels by industrial and power plants the atmospheric concentration of CO 2 has been rising over the past 50 years. Carbon capture and sequestration provides a method to prevent CO 2 from being emitted into the atmosphere. Successful carbon sequestration will require the development of many pieces of technology including development of monitoring tools and techniques. An underground laser based monitoring system was built and tested at Montana State University (MSU) to measure sub-surface CO 2 concentrations at a sequestration site. The instrument uses differential absorption spectroscopy by temperature tuning a distributed feedback diode laser over several CO 2 absorption features located at 2.004 microns. The instrument utilizes photonic bandgap fibers for sub-surface spectroscopy CO 2 concentration measurements. The instrument was tested at a controlled release facility located on the MSU campus. The field and CO 2 release are managed by the Zero Emissions Research and Technology group at MSU. Three CO 2 injection tests were done over the coarse of two summers to simulate a fault or fracture line at a sequestration site. Results from all three tests are presented showing that the underground differential absorption instrument could be used to monitor sequestration sites.

The Remote Sensing Group of the Optical Sciences Center at the University of Arizona performs absolute radiometric calibration of Earth-viewing sensors using vicarious methods. The reflectance and irradiance-based methods require the nadir-view reflectance of a calibration site at sensor overpass. Errors in these reflectance data contribute directly to errors in the retrieved at sensor radiance, and therefore errors in the calibration. This research addresses two areas of improvement for the reflectance retrieval. The discreet laboratory data of the reference panel is spectrally interpolated using the measured hemispherical reflectance rather than a polynomial fit. This interpolation better fits an absorption feature of the reference material near 2200 nm. The desired reflectance is due to the directly-transmitted solar irradiance, but field measurements also include irradiance due to diffuse light. Non-lambertian properties of the reference and surface cause the ratio of the reflected total radiances to differ from the ratio of the reflected solar radiances. This difference can be corrected using additional field measurements, shaded surface/shaded-reference, output from a radiative transfer code, RTC-only, or a combination of both, shaded-reference. For the shaded-reference and RTC-only methods the shape of the bi-directional reflectance factor of the surface must be known to better than 10% to maintain a 2% accuracy for the retrievals, while the shaded-surface/shaded-reference method does not use the surface BRF. All three methods were applied to measurements of calibrated reflectance tarpaulins, and to measurements made at White Sands Missile Range. These data demonstrate that the shaded-surface/shaded-reference and RTC-only methods improve the surface reflectance retrieval, while the shaded-reference method is too sensitive to variations between the actual and modeled diffuse sky irradiance to be useful. This research represents significant improvements in the calculation of surface reflectance for vicarious calibration. The hemispherical reflectance interpolation will reduce uncertainties in the short wave infrared by 1%, and the diffuse corrections will reduce the errors in blue by 2% in some cases.

Optical glint patterns convey information about the roughness of the surface on which they are formed. This dissertation describes two new optical instruments that relate the variations of specular laser reflections (laser glints) from the sea surface in angular, temporal, and wavenumber space to the surface roughness. Measurements from these instruments are interpreted with the objective of improving the capabilities of remote-sensing instruments that view the ocean surface. Particular attention is paid to cm waves, which are resonant structures for microwave sensors and the most significant component of optical roughness. The scanning-laser glint meter counts laser glints in 1° angular bins over a ± 75° nadir-angle range. The video laser-glint imager is a CCD video camera that images glints from an array of diode lasers. Both instruments were deployed on the research platform FLIP in the Pacific Ocean near the Oregon coast for three weeks during September 1995. Normalized histograms of angular glint counts are interpreted as the probability density function (PDF) of sea-surface slope, a Gram-Charlier expansion of which facilitates studying the variation with wind speed and atmospheric stability of moments through order four. The PDF appears approximately Gaussian, but is skewed toward downwind slopes in the along-wind axis due to asymmetric wind waves. No skewness exists in the cross-wind axis. Slope PDFs also have positive peakedness, increasing the probability of very small and large slopes relative to a Gaussian. Surface roughness is shown to depend strongly on atmospheric stability, which is proportional to the air-water temperature difference. Both the mean-square slope and the peakedness increase with negative stability (water warmer than air) relative to the neutral-stability case (water and air temperatures equal). Increased surface roughness, due to increases in wind speed or negative stability, causes glint-count fractal dimensions to increase, glint-image power spectra to flatten, and glint-image autocorrelations to appear more wrinkled. Glint-image spectra are dominated by glint-size effects, which are related to surface curvature. New ways of modeling the interaction of electromagnetic waves with the ocean surface are suggested by the new fractal and spectral characterizations of surface roughness that are introduced here.

This dissertation investigates the optical design and characterization for two distinct remote sensing applications. The first application is focused on the high precision optical phase correction for the photonic Local Oscillator (LO) designed for the Atacama Large Millimeter Array (ALMA). The phase instability in the original fiber optics design scheme is characterized and a novel, singlemode fiber-based interferometric approach to measure and actively zero out the unwanted Photonic LO phase drift is introduced. The proposed technique is implemented and characterized by using a 16 km baseline with a two element array. In the second application, the first iteration of the quasioptics design used in the ATOMMS instrument is characterized. (ATOMMS-Active Temperature, Ozone and Moisture Microwave Spectrometer-is the pathfinding implementation of an Earth and Space Atmosphere Global Remote Sensing Instrument).The diffraction problems in this design which were limiting the instrument performance were analyzed. Then different design concepts to mitigate these limitations and optimize system performance are presented.

In this thesis, methods for achieving finer scale multi-spectral classification through the use of super resolution (SR) techniques are investigated. A new super resolution algorithm Maximum a Posteriori based on the universal hidden Markov tree model (MAP-uHMT) is developed which can be applied successfully to super-resolve each multi-spectral channel before classification by standard methods. It is believed that this is the first time that a true super resolution algorithm has been applied to multi-spectral classification, and results are shown to be excellent. Image registration is an important step for SR in which misalignment can be measured for each of many low resolution images; therefore, a new and computationally efficient image registration is developed for this particular application. This improved elastic image registration method can deal with a global affine warping and local shift translations based on coarse to fine pyramid levels. The experimental results show that it can provide good registration accuracy in less computational time than comparable methods. Maximum a posteriori (MAP) is adopted to deal with the ill-conditioned problem of super resolution, wherein a prior is constructed based on the universal hidden Markov tree (uHMT) model in the wavelet domain. In order to test this prior for MAP estimation, it is first tested in the simpler and typically ill-conditioned problem of image denoising. Experimental results illustrate that this new image denoising method achieves good performance for the test images. The new prior is then extended to SR. By combining with the new elastic image registration algorithm, MAP-uHMT can super resolve both some natural video frames and remote sensing images. Test results with both synthetic data and real data show that this method achieves super resolution both visually and quantitatively. In order to show that MAPuHMT is also applicable more widely, it is tested on a sequence of long-range surveillance images captured under conditions of atmospheric turbulence distortion. The results suggest that super resolution may have been achieved in this application also.

A CCD-camera based system for the retreival of bidirectional reflectance distribution function (BRDF) data has been evaluated for vicarious calibration applications. This evaluation is done by assessing the calibration requirements necessary to retrieve BRDF data for the improvement of the vicarious calibration approach, and then by examining the calibration problem itself. A sensitivity analysis shows that for a top of the atmosphere (TOA) radiance accurate to 0.1%, instrumental biases must be under 5% while pixel-to-pixel gain variations may be as great as 10%. A method for achieving the calibration requirements using a CCD-based BRDF camera system constructed by the Remote Sensing Group (RSG) at the University of Arizona Optical Sciences Center is presented. A relative calibration level of approximately 1% across the camera array is found to be achievable given the laboratory facilities of the RSG. Software designed to extract BRDF data from the BRDF camera system output and convert the data into a form usable in the RSG's radiative transfer code are described and demonstrated on example data sets. A diffuse-light correction algorithm and software to perform the correction on BRDF camera data are described, and the software is tested against several example data sets to evaluate the retrieval accuracy of the code. Retrieval accuracies of better than 0.5% in phase and better than 0.01% in radiance have been achieved with this code using modeled data and at a 45-degree solar zenith angle. Based on these results, CCD-camera based systems can be used to improve the level of accuracy of TOA radiance calculations for vicarious calibration.

In order to develop more compact optical fiber sensing systems, modal filtering can be performed in-line by using micro-optical devices. Two such devices are a laterally offset few-moded optical fiber mechanical splice and a modal conversion optical fiber coupler. A third device, the air-gap splice used with multimode fibers, can examine the modal content of an optical fiber. A basic theoretical understanding on how these devices operate is reviewed. A splice loss calculation for few-moded optical fibers is presented. Applications of the asymmetrical few-moded mechanical optical fiber splice, the modal conversion coupler, and the air-gap splice are discussed.

Master of Science

This dissertation studies the feasibility of enhancing the spatial resolution of multi-look remotely-sensed imagery using an iterative resolution enhancement algorithm known as Projection Onto Convex Sets (POCS). A multi-angle satellite image modeling tool is implemented, and simulated multi-look imagery is formed to test the resolution enhancement algorithm. Experiments are done to determine the optimal configuration and number of multi-angle low-resolution images needed for a quantitative improvement in the spatial resolution of the high-resolution estimate. The important topic of aliasing is examined in the context of the POCS resolution enhancement algorithm performance. In addition, the extension of the method to multispectral sensor images is discussed and an example is shown using multispectral confocal fluorescence imaging microscope data. Finally, the remote sensing issues of atmospheric path radiance and directional reflectance variations are explored to determine their effect on the resolution enhancement performance.

Six spatial parameters, (x, y, z) for translation, and pitch, roll, and yaw for rotation, are used to describe the 3-dimensional position and orientation of a rigid body—the 6 degrees of freedom (DOF). The ability to measure these parameters is required in a diverse range of applications including machine tool metrology, robot calibration, motion control, motion analysis, and reconstructive surgery. However, there are limitations associated with the currently available measurement systems. Shortcomings include some of the following: short dynamic range, limited accuracy, line of sight restrictions, and capital cost. The objective of this dissertation was to develop a new metrology system that overcomes line of sight restrictions, reduces system costs, allows large dynamic range and has the potential to provide high measurement accuracy.

The new metrology system proposed in this dissertation is based on a combination of photogrammetry and optical pattern projection. This system has the potential to enable real-time measurement of a small lightweight module's location. The module generates an optical pattern that is observable on the surrounding walls, and photogrammetry is used to measure the absolute coordinates of features in the projected optical pattern with respect to a defined global coordinate system. By combining these absolute coordinates with the known angular information of the optical projection beams, a minimization algorithm can be used to extract the absolute coordinates and angular orientation of the module itself. The feasibility of the proposed metrology system was first proved through preliminary experimental tests. By using a module with a 7×7 dot matrix pattern, experimental agreement of 1 to 5 parts in 10³ was obtained by translating the module over 0.9 m and by rotating it through 60°. The proposed metrology system was modeled through numerical simulations and factors affecting the uncertainty of the measurement were investigated. The simulation results demonstrate that optimum design of the projected pattern gives a lower associated measurement uncertainty than is possible by direct photogrammetric measurement with traditional tie points alone. Based on the simulation results, a few improvements have been made to the proposed metrology systems. These improvements include using a module with larger full view angle and larger number of dots, performing angle calibration for the module, using a virtual camera approach to determine the module location and employing multiple coordinates system for large range rotation measurement. With the new proposed virtual camera approach, experimental agreement at the level of 3 parts in 10⁴ was observed for the one dimension translation test. The virtual camera approach is faster than the algorithm and an additional minimization analysis is no longer needed. In addition, the virtual camera approach offers an additional benefit that it is no longer necessary to identify all dots in the pattern and so is more amenable to use in realistic and usually complicated environments. A preliminary rotation test over 120° was conducted by tying three coordinate systems together. It was observed that the absolute values of the angle differences between the measured angle and the encoder reading are smaller than 0.23° for all measurements. It is found that this proposed metrology system has the ability to measure larger angle range (up to 360°) by using multiple coordinate systems. The uncertainty analysis of the proposed system was performed through Monte Carlo simulation and it was demonstrated that the experimental results are consistent with the analysis.

This PhD study focusses on the use of MEdium Resolution Imaging Spectrometer (MERIS) data for reliable and quantitative water-quality assessment of optically-complex waters (lake, brackish and coastal waters). The thesis is divided into two parts: A. intercalibration of reflectance measurements in different optically-complex water bodies (Paper I), and validation of various satellite processing algorithms for the coastal zone (Paper II). B. Applications: the use of MERIS data in integrated coastal zone management mostly using Himmerfjärden bay as an example. Himmerfjärden bay is one of the most frequently monitored coastal areas in the world and it is also the recipient of a large urban sewage treatment plant, where a number of full-scale nutrient management experiments have been conducted to evaluate the ecological changes due to changes in nutrient schemes in the sewage plant. Paper I describes the development and assessment of a new hyperspectral handheld radiometer for in situ sampling and validation of remote sensing reflectance.  The instrument is assessed in comparison with readily available radiometers that are commonly used in validation. Paper II has a focus on the validation of level 2 reflectance and water products derived from MERIS data. It highlights the importance of calibration and validation activities, and the current accuracy and limitations of satellite products in the coastal zone.  Bio-optical in situ data is highlighted as one of the key components for assessing the reliability of current and future satellite missions. Besides suspended particulate matter (SPM), the standard MERIS products have shown to be insufficient to assure data quality retrieval for Baltic Sea waters. Alternative processors and methods such as those assessed and developed in this thesis therefore will have to be put in place in order to secure the success of future operational missions, such as Sentinel-3. The two presented manuscripts in the applied part B of the thesis (paper III and IV), showed examples on the combined use of in situ measurements with optical remote sensing to support water quality monitoring programs by using turbidity and suspended particulate matter as coastal indicators (manuscript III). The article also provides  a new turbidity algorithm for the Baltic Sea and a robust and cost-efficient method for research and management.  A novel approach to improve the quality of the satellite-derived products in the coastal zone was demonstrated in manuscript IV. The analysis included, the correction for adjacency effects from land and an improved pixel quality screening.  The thesis provides the first detailed spatio-temporal description of the evolution of phytoplankton blooms in Himmerfjärden bay  using quality-assured MERIS data, thus forwarding our understanding of ecological processes in in Swedish coastal waters. It must be noted that monitoring from space is not a trivial matter in these optically-complex waters dominated by the absorption of coloured dissolved organic matter (CDOM). These types of coastal waters are especially challenging for quantitative assessment from space due to their low reflectance.  Papers III and IV thus also provide tools for a more versatile use in other coastal waters that are not as optically-complex as the highly absorbing Baltic Sea waters. The benefits of the increased spatial-temporal data coverage by optical remote sensing were presented, and also compared to in situ sampling methods (using chlorophyll-a as indicator).

Research funders:

European Space Agency (ESA, contract no.21524/08/I-OL)

NordForsk funding: Nord AquaRemS Ref. no. 80106

NordForsk funding:  NordBaltRemS Ref.no. 42041

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2005.
Dr. Waymond R. Scott, Committee Member ; Dr. Aaron Lanterman, Committee Member ; Dr. Paul G. Steffes, Committee Chair ; Dr. Andrew F. Peterson, Committee Member ; Dr. Judith A. Curry, Committee Member. Vita. Includes bibliographical references.

Amplification of low-light-level optical images is important for extending the range of lidar systems that image and detect objects in the atmosphere and underwater. The use of range-gating to produce images of particular range bins is also important in minimizing the image degradation due to light that is scattered backward from aerosols, smoke, or water along the imaging path. For practical lidar systems that must be operated within sight of unprotected observers, eye safety is of the utmost importance. This dissertation describes a new type of eye-safe, range-gated lidar sensing element based on Solid-state Raman Image Amplification (SSRIA) in a solid-state optical crystal. SSRIA can amplify low-level images in the eye-safe infrared at 1.556 μm with gains up to 106 with the addition of only quantum-limited noise. The high gains from SSRIA can compensate for low quantum efficiency detectors and can reduce the need for detector cooling. The range-gate of SSRIA is controlled by the pulsewidth of the pump laser and can be as short as 30-100 cm, using pump pulses of 2-6.7 nsec FWHM. A rate equation theoretical model is derived to help in the design of short pulsed Raman lasers. A theoretical model for the quantum noise properties of SSRIA is presented. SSRIA results in higher SNR images throughout a broad range of incident light levels, in contrast to the increasing noise factor with reduced gain in image intensified CCD's. A theoretical framework for the optical resolution of SSRIA is presented and it is shown that SSRIA can produce higher resolution than ICCD's. SSRIA is also superior in rejecting unwanted sunlight background, further increasing image SNR. Lastly, SSRIA can be combined with optical pre-filtering to perform optical image processing functions such as high-pass filtering and automatic target detection/recognition. The application of this technology to underwater imaging, called Marine Raman Image Amplification (MARIA) is also discussed. MARIA operates at a wavelength of 563 nm, which passes most efficiently through coastal ocean waters. The imaging resolution of MARIA in the marine environment can be superior to images produced by laser line scan or standard range-gated imaging systems.

The thermosphere is the region between approximately 80 km and 320 or more km above the earth's surface. While many people consider this elevation to be space rather than atmosphere, there is a small quantity of gasses in this region. The behavior of these gasses influences the orbits of satellites, including the International Space Station, causes space weather events, and influences the weather closer to the surface of the earth. Due to the location and characteristics of the thermosphere, even basic properties such as temperature are very difficult to measure. High spatial and temporal resolution data on temperatures and winds in the thermosphere are needed by both the space weather and earth climate modeling communities. To address this need, Space Dynamics Laboratory (SDL) started the Profiling Oxygen Emissions of the Thermosphere (POET) program. POET consists of a series of sensors designed to fly on sounding rockets, CubeSats, or larger platforms, such as IridiumNEXT SensorPODS. While each sensor design is different, they all use characteristics of oxygen optical emissions to measure space weather properties. The POET program builds upon the work of the RAIDS, Odin, and UARS programs. Our intention is to dramatically reduce the costs of building, launching, and operating spectrometers in space, thus allowing for more sensors to be in operation. Continuous long-term data from multiple sensors is necessary to understand the underlying physics required to accurately model and predict weather in the thermosphere. While previous spectrometers have been built to measure winds and temperatures in the thermosphere, they have all been large and expensive. The POET sensors use new focal plane technology and optical designs to overcome these obstacles. This thesis focuses on the testing and calibration of the two POET sensors: the Oxygen Profiling of the Atmospheric Limb (OPAL) temperature sensor and the Split-field Etalon Doppler Imager (SEDI) wind sensor

In this dissertation we use digital holographic quantitative phase microscopy to observe and measure phase-only structures due to induced photothermal interactions and nanoscopic structures produced by photomechanical interactions. Our use of the angular spectrum method combined with off-axis digital holography allows for the successful hologram acquisition and processing necessary to view these phenomena with nanometric and, in many cases, subnanometric precision. We show through applications that this has significance in metrology of bulk fluid and interfacial properties. Our accurate quantitative phase mapping of the optically induced thermal lens in media leads to improved measurement of the absorption coefficient over existing methods. By combining a mathematical model describing the thermal lens with that describing the surface deformation effect of optical radiation pressure, we simulate the ability to temporally decouple the two phenomena. We then demonstrate this ability experimentally as well as the ability of digital holography to clearly distinguish the phase signatures of the two effects. Finally, we devise a pulsed excitation method to completely isolate the optical pressure effect from the thermal lensing effect. We then develop a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase imaging technique to track a propagating nanometric capillary disturbance. We demonstrate the method's ability to accurately measure the surface energy of pure media and chemical monolayers formed by surfactants with good agreement to published values. We discuss the possible adaptation of this technique to applications for living biological cell membranes.

The Aglite system is a three-wavelength lidar plus a suite of instruments for measuring particulate emission levels near agricultural facilities. The lidar performs 3D scans of the air surrounding the facility and maps the concentration of particulates in the atmosphere surrounding the facility with high spatial and temporal resolution. Data from the conventional instruments are used to calibrate the lidar. The Aglite system includes a retrieval program, which combines the data from the lidar instrument with data from the conventional instruments to produce measurements of particulate concentration values. This thesis describes the design of the lidar data retrieval program, the development and implementation of the algorithm, and the results of measurements made on the initial field campaign. The methodology used by the Aglite system, the details of the retrieval algorithm, and the results of the measurements made by the instrument on its first field campaign are described.

Nearshore bathymetry in the Canadian Arctic is poorly surveyed, but is vital knowledge for coastal communities that rely on marine transportation for resources and development. Nautical charts currently available are often outdated and surveying by traditional methods is both time consuming and expensive. Satellite-derived bathymetry (SDB) offers a significantly cheaper and faster option to provide information on nearshore bathymetry. The two most common approaches to SDB are empirical and physics-based. The empirical approach is simple and typically does well when calibrated with high-quality in-situ data, whereas the physics-based approach is more difficult to implement and requires precise atmospheric correction. This project tests the practical use of five methods within the empirical and physics-based approaches to SDB, using Landsat 8 and Sentinel-2 satellite imagery, at seven sites across Nunavut. Methods tested include: the Ratio-Transform, Multiband, and Random Forest Regression methods (empirical) and radiative transfer modeling (physics-based) using two atmospheric correction models: ACOLITE and Deep Water Correction. All methods typically use geolocated water depth data for validation, as well as calibration for the empirical methods. Spectral reflectance for model inputs were collected in Cambridge Bay, NU. Water depth data were acquired from the Canadian Hydrographic Service. All processing was conducted within the framework of plugins developed for the open-source GIS software, QGIS. Results from the empirical methods were typically poor due to poor calibration data, though Random Forest Regression performed well when good calibration data were available. Due to poor quality validation data, error for the physics-based results cannot be adequately quantified in most places. Additionally, atmospheric correction remains a challenge for the physics-based methods. Overall, results indicate that where large, high-quality calibration datasets are available, Random Forest Regression performs best of all methods tested, with little bias and low mean absolute error in water less than 10 m deep. As such datasets are rare in the Arctic, the physics-based method is often the only option for SDB and is an excellent qualitative tool for informing communities of shallow bathymetry features and assessing navigation risk.

The molecular compositions of the atmospheres of the giant planets (Jupiter, Saturn, Uranus and Neptune) are fundamental to understanding the processes which formed these planets and the solar system as a whole. Microwave observations of these planets probe regions in their atmospheres from approximately 0.1 to several bars, a process otherwise unachievable by visible and infrared means. Many gases and various cloud layers influence the millimeter wave spectra of the outer planets; however phosphine and ammonia are the main microwave absorbers at Saturn at pressures less than two bars. Understanding the pressure induced absorption of both constituents at observational frequencies is therefore vital to the analysis of any observational data. Laboratory measurements have been conducted to measure the microwave absorptivity and refractivity of phosphine and ammonia at Ka-band (32-40 GHz) and W-band (94 GHz), under conditions characteristic of the atmosphere of Saturn. The results were used to verify the accuracy of the phosphine formalism created by Hoffman et. al (2001) for use at millimeter wavelengths. Based on the laboratory measurements conducted, new formalisms were also created to express the opacity of ammonia at the measured frequencies. An important method for the study of planetary atmospheres is the radio occultation experiment ??method that uses radio links between Earth, and the spacecraft which passes behind the planet. The Cassini mission to Saturn, which will be conducting such experiments at Ka-band as well as S (2.3 GHz) and X (8.4 GHz) bands, has prompted the development of a radio occultation simulator used to calculate excess Doppler shifts and attenuation profiles for Saturn, utilizing the newest formalisms for phosphine and ammonia. The results indicate that there will be unambiguous detection and profiling of phosphine and ammonia, and predictions are made for the pressures at which loss of signal is anticipated.

Orientador: Enner Herenio de Alcântara
Resumo: O Material Particulado em Suspensão (MPS) é o principal componente em sistemas aquáticos. Elevadas concentrações de MPS implicam na atenuação da luz, e ocasionam alterações das taxas fotossintéticas. Além disso, a presença de MPS no sistema aquático pode aumentar os níveis de turbidez, absorver poluentes e podem ser considerados como um indicativo de descargas de escoamento superficial. Portanto, monitorar as concentrações de MPS é essencial para a gerar informações técnicas que subsidiem o correto manejo dos recursos aquáticos, prevenindo colapsos hidrológicos. O sensoriamento remoto se mostra como uma eficiente ferramenta para monitorar e mapear MPS quando comparada às técnicas tradicionais de monitoramento, como as medidas in situ. Entretanto, diante de uma grande e complexa variabilidade de componentes óticos, desenvolver modelos de MPS por meio do sinal registrado em sensores remotos é um desafio. Diversos modelos foram desenvolvidos para reservatórios, lagos e lagoas específicos. Atualmente, não há um único modelo capaz de estimar MPS em reservatórios brasileiros em cascata. Com o objetivo de estimar as concentrações de MPS de forma acurada, o objetivo desta tese foi desenvolver um modelo semi-analítico capaz de estimar valores de coeficiente de atenuação, Kd, por meio do uso dos coeficientes de absorção e espalhamento e, consequentemente, utilizar os valores de Kd para estimar as concentrações de MPS. A adoção desta estratégica se baseou na atenuação da luz ao longo da... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Suspended particulate matter (SPM) is the main component presented within aquatic system. High levels of SPM concentration attenuate the light affecting the photosynthesis rates. Besides, can increase turbidity levels, absorb pollutions and is an indicative of runoff discharges. Therefore, monitoring SPM concentrations is essential to provide reliable information for a correct water management to prevent hydrological collapse. Remote sensing emerges as an efficient tool to map and monitor SPM when compared to traditional techniques, such as in situ measurements. Nevertheless, considering a widely range of optical components, modeling the remote sensing signal in terms of SPM is a challenge. Several models were developed for specific reservoirs, lakes or ponds. Up to our knowledge, there is not a single model capable to retrieve SPM in Brazilian linked reservoirs in a cascade system. In order to accurately estimate SPM, the aim of the thesis was developed a semianalytical model capable to estimate Kd via absorption and backscattering coefficients, and then, use Kd to derive SPM. This approach was adopted because SPM directly contributes to the light attenuation within the water column. Firstly, optical features were investigated. It was found that each reservoir presented a specific optical active component (OAC) dominance, such as Barra Bonita, the first reservoir in cascade is dominated by organic SPM, while Nova Avanhandava, the last reservoir in cascade is dominated by ino... (Complete abstract click electronic access below)
Doutor

Orientador: Jose Antonio Siqueira Dias
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Os sensores a fibra óptica são especialmente indicados para operarem em ambientes eletricamente ruidosos, uma vez que são imunes aos efeitos da interferência eletromagnética (EMI) encontrados nestes ambientes. Tal característica faz com que os sensores ópticos sejam altamente vantajosos para as aplicações nos sistemas de sensoreamento utilizados pelas empresas de energia elétrica. Este trabalho apresenta o desenvolvimento de um protótipo de baixo custo de um sensor óptico de alta tensão com alta confiabilidade, que pode ser usado para monitorar o estado ou limiares de tensão em uma rede elétrica. Uma técnica de detecção do sinal através do sensoreamento com grades de Bragg é apresentada, fabricada e avaliada. Os resultados mostram que a técnica de detecção empregada, onde a amplitude ac do sinal da luz refletido é medida em um fotodiodo, mostra-se adequada para a aplicação em sensores de alta tensão. As medidas realizadas em um protótipo de sensor de alta tensão com fibra óptica com grade de Bragg indicam que o esquema de detecção desenvolvido é promissor, e pode ser usado para medir outros sinais dinâmicos que respondam a um esforço de pequena amplitude aplicado à fibra óptica. O protótipo desenvolvido permitiu a detecção de tensões variando na faixa de 143 V -60kY. É também apresentada uma nova técnica para estabilizar termicamente grades de Bragg com a temperatura, utilizando o sinal uma fibra extra, casada com a fibra do sensor, que através de um circuito de realimentação atua no elemento aquecedor/resfriador do laser semicondutor(thenno electrical cooler), para fazer com que o comprimento de onda do laser siga as variações da sintonia da grade de Bragg sensora, causadas por variações da temperatura. Esta técnica inovadora poderá ser utilizada para a compensação térmica de outros tipos de sensores com grade de Bragg, permitindo a fabricação de sensores de baixo custo e grande simplicidade de implementação
Abstract: Fiber optics sensors are specially indicated to operate in noisy electrical environments because they are immune to the effects of electromagnetic interference (EM!) found in these environrnents. Such characteristic makes these sensors highly advantageous to the applications in the measurement systems used by electrical energy companies. This work presents the development of a prototype of a high-voltage and a low cost optical sensor which is used to monitor the state or voltage threshold with a high reliability. A technique for the detection of fiber Bragg grating sensors signals was developed, presented and tested. The experimental results showed that the developed detection technique, where the ac amplitude of the signal result from the light reflection is measured with a photodiode is adequate for high voltage sensing applications. The prototype of the high voltage fiber Bragg sensor was tested and the measured results indicate that the technique can be used to detect any other dynarnic measurand which induces a small strain amplitude when applied to the fiber Bragg grating. The developed prototype detected voltages in the range from 143 V to 60 kV. It is also presented a new technique for obtaining temperature independent fiber Bragg gratings, using a feedback circuit which uses the signal detected from a matched fiber and generates a signal which actuates on the thermo electrical cooler of the semiconductor laser, modifying the laser' s output wavelength, in orer to accurate track the Bragg wavelength shifts caused by temperature variations. This novel technique can be used for the fabrication of simple and low-cost temperature compensated fiber Bragg grating sensors
Doutorado
Eletrônica, Microeletrônica e Optoeletrônica
Doutor em Engenharia Elétrica