The Optical Spectrograph and InfraRed Imaging System (OSIRIS) satellite instrument spearheaded by a team of researchers at the University of Saskatchewan has provided scientists with 13 years of information about the state of the atmosphere. The success of the mission has motivated further development of the technology in a next generation instrument called the Canadian Atmospheric Tomography System (CATS) to provide better spatial and spectral resolution through a successive satellite mission. This work details the development of a proof-of-concept prototype built to test the validity of the CATS optical design. This thesis project utilized the developmental model built for the OSIRIS mission. The major modification made to the instrument replaced the optical element that defines the instrument’s field of view. This new development transformed the original single line of sight utilized by the satellite based OSIRIS instrument into three separate fields of view, which increased the imaging capabilities of the instrument. The new system has improved spatial resolution by collecting spectral information from three separate regions in the atmosphere in a single exposure, as opposed to the single region imaged by the original system. The newly developed prototype was tested on the platform of a stratospheric balloon. This test platform offered the capabilities to make limb scattered measurements similar to those that are made by a satellite based instrument. However, from the balloon geometry, the instrument required an additional pointing system to redirect the line of sight over stratospheric tangent altitudes. The design and test of this pointing system is also detailed in this work.

The development of remote sensing satellite-borne instrumentation for the study of the Earth’s atmosphere has provided an immense increase in our understanding of atmospheric trends and processes. The Canadian built OSIRIS satellite instrument uses the limb scatter technique to measure scattered sunlight for the retrieval of vertical profiles of atmospheric species such as ozone. Recently, the next generation instrument, CATS, based on the OSIRIS design, is under development to continue OSIRIS measurements into the future. One key optical design change for CATS is the ability to measure simultaneously over multiple fields of view. However, this new optical design concept needs to be tested and evaluated. To achieve this, a prototype slit plate was installed into the preflight developmental version of OSIRIS, called OSIRIS-DM, for testing in the laboratory and on a stratospheric balloon. In this thesis work, an evaluation of the performance of this multi-slit instrument was undertaken through laboratory calibrations and limb scatter measurement collection. The calibration process includes a wavelength registration, a spectral point spread function analysis, a relative calibration and an absolute calibration, all performed with laboratory equipment. Along with laboratory calibrations, this thesis work involved preparation for the stratospheric balloon mission including the development of a flight ready electronic control and communication system to operate OSIRIS-DM during the mission. The upgraded instrument was launched on September 19, 2014, and ascended to a stable float altitude of 36.5 km. The collected flight measurements were used to evaluate the calibrations and general instrument performance. Overall, the laboratory calibrations proved to be sufficiently accurate and the measurement collection produced multiple spectra that may be used for atmospheric analysis in the future. These results show that the multi-slit design of the slit plate produces an instrument that can be reliably calibrated and implemented for limb scatter measurement collection.

Thesis (Ph. D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (p. [127]-142). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Dept. of Geophysical Sciences, August 1999. / Includes bibliographical references. Also available on the Internet.

Networks of ground-based and satellite borne instruments to measure ultraviolet (UV) sunlight and total column ozone have greatly contributed to an understanding of increased amounts of UV reaching the surface of the Earth caused by stratospheric ozone depletion. Increased UV radiation has important potential effects on human health, and agricultural and ecological systems. Observations from these networks make it possible to monitor total ozone decreases and to predict ozone recovery trends due to global efforts to curb the use of products releasing chemicals harmful to the ozone layer. Thus, continued and expanded global monitoring of ozone and UV is needed. However, existing automatic stratospheric ozone monitors are complex and expensive instruments. The main objective of this research was the development of a low-cost fully automated total column ozone monitoring instrument which, because of its affordability, will increase the number of instruments available for ground-based observations. The new instrument is based on a high-resolution fiber optic spectrometer, coupled with fiber optics that are precisely aimed by a pan and tilt positioning mechanism and with controlling programs written in commonly available software platforms which run on a personal computer. This project makes use of novel low-cost fiber optic spectrometer technology. A cost advantage is gained over available units by placing one end of the fiber outdoors to collect sunlight and convey it indoors, thereby allowing the spectrometer and computer to be placed in a controlled environment. This reduces the cost of weatherproofing and thermal compensation. Cost savings also result from a simplified sun targeting system, because only a small pan and tilt device is required to aim the lightweight fiber optic ends. Precision sun-targeting algorithms, optical filter selection, and software to derive ozone from spectral measurements by the spectrometer are a major contribution of this project. This system is a flexible platform which may be adapted to study other atmospheric constituents such as sulfur dioxide, nitrous oxides, and haze.

Measuring the composition of the stratosphere, and understanding the processes regulating it, have become,in the last few decades, top priorities in the scientific community, particularly since the discovery ofthe ozone hole in the 1980s. While a lot has indeed been done in monitoring ozone, other constituents also influence the stratosphere’s composition, and interfere namely with ozone, affecting its chemical and dynamical balance. Among these is nitric acid (HNO3 ) which is a reservoir for ozone depleting NOx ,but also a key player in the formation of polar stratospheric clouds which, by turning inert species into active radicals, enhance the ozone depletion further. The nadir-viewing IASI instrument is a very good means of obtaining simultaneous data of nitric acid and ozone. Indeed, it measures the radiation of the Earth’s atmosphere in the thermal infrared spectral range, which allows it to measure even at night. This is crucial to the study of polar processes, since they occur mostly during the polar winter, when no light reaches these latitudes. Thanks to its design and its technical characteristics, the IASI instrument provides data all-year round, for every location on the Earth. The purpose of this work is to use this unique set of IASI data to understand what drives the variability of HNO3 in the stratosphere. No study so far has focused on the factors affecting the time and spatial distributions of nitric acid to the extent and scale we propose here. We aim to identify and quantify these factors, and to compare them with the drivers of ozone variability. Nitric acid data are thus obtained for the 10 years of IASI observation (2008 − 2017), and vertical profiles are retrieved in near-real time thanks to the FORLI algorithm developed at ULB. The first part of the present work provides a detailed characterization of the IASI FORLI-HNO3 data set in terms of vertical sensitivity and errors. We show that the HNO3 maximum is found around 20 km altitude, where we also find the maximum sensitivity of the measurements to the vertical profile. The analysis of the averaging kernels shows us that only one level of information can be extracted from the vertical profile, which constrains the rest of our analyses to the use of a total (or almost total) column. We also find that the IASI measurements tend to overestimate slightly the HNO3 column in the upper troposphere/lower stratosphere region of the profile. The data set is validated against ground-based FTIR measurements at different latitudes: we find good agreement between IASI and the FTIR data, which confirms that IASI manages to reproduce the HNO3 columns and their seasonality accurately. Comparisons with a state of the art atmospheric model data are also shown, and suggest that improvement is still largely needed in models to represent the HNO3 distributions accurately. The use of a data-assimilated model (BASCOE) shows a much better agreement with the IASI observations. The next part of the work describes the geophysical analyses carried out, and details the first time series and global distributions of HNO3 from IASI. After describing the various (mostly polar) processes at play observed in the time series, the question of the formation of the polar stratospheric clouds is raised, and further results are shown about the temperature at which these form. While a fixed threshold (195 K) is usually used for geophysical analyses, we find from the observational IASI data set that this fixed temperature can vary substantially depending on local conditions and on altitude. The last sections use multivariate linear regressions to fit the HNO3 and O3 time series, featuring various chemical and dynamical variables in order to identify what factors are responsible for their respective variability. We include the variables most commonly used in such kind of study, i.e. a linear trend, harmonical terms to account for the annual seasonality, and proxies for the quasi-biennial oscillation, the multivariate ENSO index, and the Arctic and Antarctic oscillations. The novelty of our work resides in the addition of a proxy for the volume of polar stratospheric clouds to account for the strong denitrification observed in the HNO3 time series in polar regions. We find that the annual cycle, encompassing the solar seasonality and the Brewer-Dobson circulation, is the factor explaining most of the variability of both HNO3 and O3 ,at almost all latitudes. In the polar regions, however, the volume of polar stratospheric clouds is a key factor contributing the most to their variability. Globally, the same factors explain the same portion of both HNO3 and O3 variability. In the last part of the thesis, we conclude and provide a preliminary co-analysis of HNO3 and O3 from the 10-year IASI data. The results are encouraging and highlight the potential of the IASI measurements to monitor the polar processes on various scales. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

L’étude des aérosols stratosphériques est importante pour comprendre le bilan radiatif terrestre. A l’heure actuelle, notre représentation des différents types de particules stratosphériques et leurs répartitions spatiale et temporelle n’est pas complète. Au cours de cette thèse, nous tentons de montrer que la mesure de la concentration en particules sous ballon météorologique au moyen d’un nouveau mini compteur de particules, le LOAC, pourrait permettre de rendre compte de la possible variabilité locale du contenu en aérosols stratosphériques dans la gamme de taille 0,2 à 100 μm en diamètre. La première partie de ce travail consiste à caractériser plus précisément les performances du LOAC sous ballon météorologique appliqué à la mesure en stratosphère. La seconde partie propose une analyse comparée du contenu en aérosols stratosphériques obtenu par LOAC, à partir de lâchers de ballons en France régulièrement depuis 3 ans et plus ponctuellement à l’étranger dans des situations particulières (volcan, mousson), et par d’autres types de données (Observations spatiales, lidar sol et simulation globale). Nous montrons alors que l’instrument possède une limite de détection rendant difficile la mesure des particules submicroniques lors de période de fond en moyenne stratosphère pour des concentrations de l’ordre d’une particule par cm3. Dans sa version actuelle, le LOAC permet de documenter les panaches volcaniques en troposphère ainsi qu’en basse stratosphère. En perspective, nous proposons des directions pour la calibration et l’analyse des futures données d’une nouvelle génération de l’instrument en développement. / The study of the stratospheric aerosols is important to our understanding of the terrestrial radiative budget. Our current comprehension of the different types of stratospheric particles and their spatial and temporal distribution is incomplete. In the present study, we try to show that measuring particle concentrations by the means of a new balloon-borne miniature particle counter, the LOAC, may allow us to determine the local variability in stratospheric aerosols in the size range 0.2 – 100 μm in diameter. In that respect, the PhD thesis consists of a first phase of a more accurate characterisation of the LOAC’s performances under balloon-borne measurement. A second phase consists of comparative analysis of stratospheric aerosol content based on a LOAC dataset obtained during a continuous campaign of balloon launches in France, along with some occasional flights abroad under particular circumstances (volcanic eruption, monsoon). Thus we show that the LOAC has a detection limit that restricts the measurement of submicronic particles in volcanic quiescent periods for concentrations lower than typically 1 particle per cm3. In its current version, the LOAC allows us to characterise aerosols in volcanic plumes in the troposphere and lower stratosphere. And, further, we propose directions concerning possible calibration and analysis strategies for the future data from the next generation of the LOAC currently in development.

A new retrieval algorithm has been developed based on the Optimal Estimation (OE) approach, which retrieves lognormal aerosol size distribution parameters from multiwavelength aerosol extinction data, as measured by the Stratospheric Aerosol and Gas Experiment (SAGE) II in the lower stratosphere. Retrieving these aerosol properties becomes increasingly more difficult under aerosol background conditions, when tiny particles (« 0.1 µm) prevail, to which the experiment is nearly or entirely insensitive. A successful retrieval algorithm must then be able (a) to fill the 'blind spot' with suitable information about the practically invisible particles, and (b) to identify 'the best' of many possible solutions. The OE approach differs from other previously used aerosol retrieval techniques by taking a statistical approach to the multiple solution problem, in which the entire range of possible solutions are considered (including the smallest particles) and characterized by probability density functions. The three main parts of this thesis are (1) the development of the new OE retrieval algorithm, (2) the validation of this algorithm on the basis of synthetic extinction data, and (3) application of the new algorithm to SAGE II measurements of stratospheric background aerosol. The validation results indicate that the new method is able to retrieve the particle size of typical background aerosols reasonably well, and that the retrieved uncertainties are a good estimate of the true errors. The derived surface area densities (A), and volume densities (V ) tend to be closer to the correct solutions than the directly retrieved number density (N), median radius (R), and lognormal distribution width (S). Aerosol properties as retrieved from SAGE II measurements (recorded in 1999) are observed to be close to correlative in situ data. In many cases the OE and in situ data agree within the (OE and/or the in situ ) uncertainties. The retrieved error estimates are of the order of 69% (σN), 33% (σR), 14% (σS), 23% (σA), 12% (σV), and 13% (σReff ). The OE number densities are generally larger, and the OE median particle sizes are generally smaller than those N and R retrieved by Bingen et al. (2004a), who suggest that their results underestimate (N) or overestimate (R) correlative in situ data due to the 'small particle problem'. The OE surface area estimates are generally closer to correlative in situ profiles (courtesy of T. Deshler, University of Wyoming), and larger than Principal Component Analysis (PCA) retrieval solutions of A (courtesy of L. W. Thomason, NASA LaRC) that have been observed to underestimate correlative in situ data by 40-50%. These observations suggest that the new OE retrieval algorithm is a successful approach to the aerosol retrieval problem, which is able to add to the current knowledge by improving current estimates of aerosol properties in the lower stratosphere under low aerosol loading conditions.

The aim of the research documented in this thesis was to explore issues associated with the development of instrumentation for life detection and characterisation in a planetary exploration context. Within this aim, the following objectives had to be achieved: 1. To consider current and near-future single molecule detection (ultra-low lower limit of detection) analytical techniques that would be compatible with development into a Space qualifiable in situ analytical instrument for the detection of biomarkers in a planetary exploration context. 2. To practically consider the consequences of Planetary Protection and Contamination Control on the development of a sample return instrumentation in a planetary exploration context. 3. To consider the implications of flying an in situ instrument on-board a stratospheric balloon platform in order to apply them into a specific planetary exploration mission: In order to achieve the objectives described above, the following work was pursued:  A desk-based European Space Agency (ESA) study was carried out which entailed producing a literature review on single molecule detection technologies that had to be validated by the expert community. This was done by organising an International Workshop on Single Molecule Detection Technologies for Space Applications in March 2009 at Cranfield University, UK. The approved technologies then had to be analysed with standard analytical techniques (i.e., tradeoffs) in order to propose a specific technology for development and present its breadboard implementation and test plans at the end of the study.  A sample return experiment implementing PP&CC constraints and protocols was designed, built, tested and flown on-board the ESA, Swedish Space Corporation (SSC), Swedish National Space Board (SNSB) and German Space Agency (DLR) BEXUS stratospheric balloon platform. The biological and engineering results obtained from the sample return flight were then analysed and lessons learnt obtained for future flights.  Another desk-based study was performed to research future stratospheric balloon platforms for the exploration of Venus’ cloud layer. The in situ instrument previously proposed for the detection of biomarkers for planetary exploration missions was then put forward as a possible payload for a Venusian stratospheric balloon platform and approved by experts during the Venus Exploration Analysis Group (VEXAG) conference held in August 2011 in Washington D.C, USA. The first part of the research involved studying ultra-low lower limit of detection technologies as these have the potential to impact significantly on the technological and scientific requirements of future Space missions. Two systems were proposed: one based on Tandem Mass Spectrometry (with Cylindrical Ion Trap analysers) followed by Surface Enhanced Raman Scattering spectroscopy to create an MS/MS-SERS instrument for the detection of astrobiology biomarkers in Martian regolith, Europan ice and samples from Titan’s hydrocarbon lakes; and a second one as a Stand-Alone SERS system for the detection of biomarkers in Enceladean plumes, Venusian clouds and cometary coma. The second part of the research practically explored the design of instrumentation for stratospheric balloon platforms. CASS•E, the Cranfield Astrobiological Stratospheric Sampling Experiment, was a life detection experiment that aimed to be capable of detecting stratospheric microorganisms. The experiment consisted of a pump which drew air from the Stratosphere through a 0.2 μm collection filter which retained any microorganisms and >0.2 μm particulates present in the pumped air. Due to the expected rarity of microbes in the Stratosphere compared to the known levels of contamination at ground level, Planetary Protection and Contamination Control (PP&CC)constraints were introduced. Therefore PP&CC protocols were followed to implement Space qualified cleaning and sterilisation techniques; biobarrier technology was implemented to prevent re-contamination of the instrument after sterilisation; and cleanliness and contamination was monitored throughout assembly, integration and testing. The third part of the research demonstrated how an instrument from the first part of the study could be proposed as a payload on-board a stratospheric balloon platform with a focused mission context, i.e., a life detection mission for Venus. Therefore, the research concluded with the proposal of a payload for a Venus mission based on SERS technology on-board a stratospheric balloon platform to search for life above or in the mid Venusian cloud cover.

Cette thèse a pour but de préparer un travail d’extrapolation de l’impact des overshoots stratosphériques (SOC) sur le bilan de vapeur d’eau (VE) dans la couche de la tropopause tropicale (TTL) et dans la basse stratosphère à l’échelle continentale.Pour ce faire, nous profitons des mesures de la campagne de terrain TRO-Pico tenue à Bauru, au Brésil, pendant deux saisons convectives/humides en 2012 et 2013, et de plusieurs simulations numériques de la TTL sur un domaine englobant une grande partie de l’Amérique du Sud avec le modèle méso-échelle BRAMS.Premièrement, nous effectuer une simulation d’une une saison humide complète sans tenir compte des SOC. Cette simulation est ensuite évaluée pour d’autres caractéristiques clés typiques (température de la TTL, VE, sommets de nuages et ondes de gravité) dans la TTL. En l’absence de SOC et avant d’extrapoler son leur impact, nous démontrons que le modèle reproduit correctement les caractéristiques principales de la TTL. L’importance de l’ascension lente à grande échelle par rapport aux processus convectifs profonds à échelle finie est ensuite discutée.Deuxièmement, à partir de simulations BRAMS à fine à échelle de cas de SOC observés pendant TRO-Pico, nous déduisons des quantités physiques (flux de glace, bilan de masse de glace, tailles des SOCs), qui serviront à définir un forçage de l’impact des overshoots dans des simulations à grande échelle. Nous montrons un impact maximum d’environ 2 kt en VE et 6 kt de glace par SOC. Ces chiffres sont 30% nférieurs pour un autre réglage microphysique du modèle. Nous montrons que seul trois types d’hydrométéores du modèle contribuent à cette hydratation. / This dissertation aims at laying a foundation on upscaling work of the impact of stratospheric overshooting convection (SOC) on the water vapor budget in the tropical tropopause layer (TTL) and lower stratosphere at a continental scale.To do so, we take advantage of the TRO-Pico field campaign measurements held at Bauru, Brazil, during two wet/convective seasons in 2012 and 2013, and perform accordingly several numerical simulations of the TTL which encompass through a large part of south America using the BRAMS mesoscale model.Firstly, we adopt a strategy of simulating a full wet season without considering SOC. This simulation is then evaluated for other typical key features (e.g., TTL temperature, convective clouds, gravity wave) of the TTL. In the absence of SOC and before upscaling its impact, we demonstrate that the model has a fair enough ability to reproduce a typical TTL. The importance of large-scale upwelling in comparison to the finite-scale deep convective processes is then discussed.Secondly, from fine scale BRAMS simulations of an observational case of SOC during TRO-Pico, we deduce physical parameters (mass flux, ice mass budget, SOC size) that will be used to set a nudging of the SOC impact in large-scale simulations. A typical maximum impact of about 2kt of water vapor, and 6kt of ice per SOC cell is computed. This estimation is 30% lower for another microphysical setup of the model. We also show that the stratospheric hydration by SOC is mainly due to two types of hydrometeors in the model.