Seit 2015 gibt es Doppler-LIDAR-Messungen der Windgeschwindigkeit über Leipzig. Diese Messungen werden zum einen vom HALO Photonics Streamline Doppler-LIDAR am Leipziger Institut für Troposphärenforschung (TROPOS) sowie vom Leosphere Windcube 8 Doppler-LIDAR am Leipziger Institut für Meteorologie (LIM) aufgenommen. In dieser Arbeit werden insbesondere die Daten des Windcubes bezüglich der horizontalen Windgeschwindigkeit, der Windrichtung und der Turbulenzintensität bis in eine Höhe von ca. 500 m ausgewertet. Der Vergleich mit dem HALO Photonics Streamline Doppler-LIDAR zeigt gute Korrelationen zwischen beiden Geräten. Die Ergebnisse beinhalten unter anderem eine gute Übereinstimmung mit der Ekman-Theorie. Auch die erhöhte Rauhigkeit der Stadtfläche gegenüber dem ländlichen Raum wird in der Auswertung deutlich. Es wurde ein Verfahren getestet, das es erlaubt, den turbulenten Diffusionskoeffizienten und die aerodynamische Rauhigkeitslänge aus den Messwerten abzuleiten und erste Abschätzungen dieser Größen vorzunehmen. Diese Arbeit legt nahe, den Einsatz der Fernerkundungsmessung zur Bestimmung der urbanen Grenzschichtdynamik fortzusetzen und wenn möglich zu erweitern. / Since 2015 Doppler-LIDAR measurements above Leipzig are available. The Leibniz Institute for Tropospheric Research (TROPOS) operates a HALO Photonics Streamline Doppler-LIDAR while the Institute of Meteorology Leipzig uses a Leosphere Windcube 8 Doppler-LIDAR. In this study mainly meausrements of the Windcube for horizontal wind velocity, wind direction and turbulence intensity below 500 m are evaluated. The comparison to the HALO Photonics Streamline LIDAR shows good correlations between both devices. Among others, the results include good agreements with the Ekman theory. Additionally the increased roughness of the city surface compared to rural areas becomes apparent. A way to determine characteristic quantities like the turbulent diffusion coefficient and the aerodynamic roughness length is described and initial estimations were conducted. This study suggests to continue and if possible expand such remote sensing measurements for analyses of urban boundary layer dynamics.

L'atmosphère moyenne de la Terre est un laboratoire naturel pour les études de la dynamique géophysique des fluides et de l'optique pour la mesure des gaz. Les recherches dans cette région ont longtemps été limitées par le manque d'observations à long terme susceptibles de couvrir l'ensemble de la région, de la troposphère à la haute mésosphère et à la thermosphère inférieure. Les dernières décennies ont vu la construction de nombreux observatoires au sol et le lancement d'instruments par satellite dans le but de fournir les mesures nécessaires pour comprendre la chimie, la dynamique et les changements climatiques à long terme de l'atmosphère moyenne. La télédétection atmosphérique, tant au sol que dans l’espace, présente des avantages et des inconvénients évidents. Les premiers étant capables de fournir des mesures bien calibrées et à haute résolution sur un seul site et les derniers permettant une couverture globale au prix de la résolution et d'un certain degré de certitude lors de l'étalonnage. Pour ce travail, nous utilisons des mesures de température obtenues à l'aide d'une technique de télédétection au sol basée sur le lidar à diffusion de Rayleigh et nous effectuons des comparaisons systématiques avec les profils de température générés à l'aide de trois instruments de télédétection passif basés sur des satellites: Sondeur Micro-onde sur satellite Aura (MLS). Sondage de l'atmosphère par radiométrie des émissions à large bande (SABER) et surveillance mondiale de l'ozone par occultation d'étoiles (GOMOS).Ce manuscrit a trois résultats principaux: 1a) Résultats de plusieurs améliorations de l’algorithme de la température lidar, qui ont permis de corriger un bias froid sur les températures mésosphériques jusqu’à 20 K à 90 km. 1b) Meilleur accord entre les températures du lidar et les profils de température SABER et MLS entre 70 km et 90 km. 1c) Une validation croisée entre les températures d’un lidar de température de Rayleigh et d’un lidar d’ozone co-localisés, qui donne confiance en la stabilité de la technique du lidar et justifie l’utilisation de la température par lidar comme base de données de référence pour la validation par satellite. 2a) Présentation d’une comparaison décennale entre les températures lidar validées et les températures produites par SABER et MLS. 2b) Nous montrons un biais froid dans les mesures satellitaires par rapport au lidar (-6 K pour SABER et -17 K pour MLS) dans la région de stratopause, un biais chaud (6 K près de 60 km) dans la mésosphère d’été, et un biais structuré verticalement pour MLS (-4 à 4 K) qui couvre la moyenne atmosphère. 2c) Nous réduisons l'ampleur du biais en dècallant verticalement la hauteur de la stratopause satellite et constatons une amélioration de la comparaison de température lidar-satellite qui en résulte. Ce résultat a des implications importantes pour la notification des températures des satellites en fonction de la hauteur géopotentielle. 3a) La comparaison des profils de température lidar avec la nouvelle base de données de température GOMOS montre que les altitudes géométriques des satellites peuvent être mieux estimées par les techniques d'occultaion que par l'inférence des niveaux de pression à partir des données radiométriques 3b) de l'effet des marées sur les comparaisons de température entre lidar et satellite lorsque Le passage supérieur du satellite est décalé dans le temps par rapport à la mesure lidar et peut être de l'ordre de 2 à 4 K en fonction de la phase de l'heure solaire. / The Earth's middle atmosphere is a pristine natural laboratory for the study of geophysical fluid dynamics and optics in neutral gasses. Research in this region has long been limited by a lack of long-term observations which are capable of covering the entire region from the troposphere to the upper mesosphere and lower thermosphere. Past decades have seen the construction of many ground based observatories and launches of satellite based instruments in an effort to provide the measurements needed to understand the chemistry, dynamics, and long-term climactic changes in the middle atmosphere. Both ground-based and space-based atmospheric remote sensing have clear strengths as well as limitations; the former being able to provide high resolution, well calibrated measurements at a single site and the latter allowing for global coverage at the cost of resolution and some degree of certainty in calibration. For this work we are using temperature measurements produced from a Rayleigh-scatter lidar ground-based remote sensing technique and making systematic comparisons to temperature profiles produced from three passive scanning satellite-based remote sensing instruments: Microwave Limb Sounder on the Aura satellite (MLS), Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), and Global Ozone Monitoring by Occultation of Stars (GOMOS).This manuscript has three main results: 1a) Results of several improvements to the lidar temperature algorithm resulting in a cooling of the mesospheric temperatures by up to 20 K at 90 km. 1b) Better agreement between the cooled lidar temperatures and temperature profiles from SABER and MLS between 70 km and 90 km. 1c) A cross-validation between temperatures from a co-located Rayleigh temperature lidar and ozone lidar which provides confidence in the stability of the lidar technique and justification for the use of lidar temperatures as a reference database for satellite validation. 2a) Presentation of a decadal comparison between the validated lidar temperatures and the temperatures produced by SABER and MLS. 2b) We show a cold bias in the satellite measurements with respect to the lidar (-6 K for SABER and -17 K for MLS) in the stratopause region, a warm bias (6 K near 60 km) in the summer mesosphere, and a vertically structured bias for MLS (-4 to 4 K) which spans the middle atmosphere. 2c) We reduce the magnitude of the bias by vertically shifting the height of the satellite stratopause and see an improvement in the resulting lidar-satellite temperature comparison. This result has important implications for the reporting of satellite temperatures as a function of geopotential height. 3a) Comparison of lidar temperature profiles with the newly created GOMOS temperature data base shows that satellite geometric altitudes can be better estimated by occultaion techniques than by inference of pressure levels from radiometric data 3b) The effect of tides on lidar to satellite temperature comparisons when the satellite overpass is temporally offset from the lidar measurement can be on the order of 2 to 4 K depending on the phase of the solar hour.

Un algorithme permettant d’estimer précisément les paramètres des tourbillons de sillage (positions et circulations) en utilisant les données spectrales fournies par un LIDAR a été développé. Il s’articule en 3 grandes étapes : La première permet de détecter la présence de tourbillon et d’en faire une localisation grossière grâce à la méthode des enveloppes de vitesses. La seconde étape a pour but d’affiner l’estimation des positions des tourbillons en utilisant une optimisation du critère des moindres carrés. Cette étape permet également de faire une première estimation de la circulation des tourbillons. La troisième et dernière étape se concentre sur l’estimation des circulations des tourbillons en maximisant le critère de vraisemblance. Les estimations sont de plus en plus fines et se concentrent au fur et à mesure sur les paramètres les plus critiques. La mise au point de cet algorithme a nécessité d’utiliser plusieurs modèles (LIDAR, tourbillons de sillage, atmosphère) et de formuler un certain nombre d’hypothèses et approximations simplificatrices afin d’atteindre un coût calculatoire raisonnable. L’algorithme proposé a ensuite fait l’objet d’une évaluation de performances, l’intérêt étant porté sur la robustesse par rapport aux différents bruits altérant la mesure, en particulier celui lié à la turbulence atmosphérique et par rapport aux erreurs de modèle. Cette évaluation a été menée à la fois sur des données simulées à l’aide de modèles paramétriques simplifiés, et sur des données de simulations aux grandes échelles.Les paramètres instrumentaux du LIDAR constituent de potentiels degrés de liberté pour améliorer les performances de l’estimateur, en particulier pour les grandeurs les plus critiques, c’est-à-dire les valeurs de circulation. Le calcul des performances de l’estimateur nécessitant un coût de calcul non négligeable, il se prête mal à des fins d’optimisation. C’est pourquoi une étude de l’influence des paramètres du LIDAR sur la Borne de Cramér-Rao (BCR) a été menée. Cette étude a permis de mieux comprendre l’influence des paramètres instrumentaux et d’aboutir à une configuration optimale pour la BCR. / An algorithm was developed to estimate precisely wake vortices parameters (positions and circulations) using spectral data provided by a LIDAR. It is articulated in 3 main stages: The first one allows to detect the presence of vortices and to make a rough localization thanks to the method of the velocity envelopes. The second step is to refine the estimation of vortex positions using an optimization of the least squares criterion. This step also permits to make an first estimation of the vortices circulation. The third and final step focuses on estimating vortex circulations by maximizing the likelihood criterion. Estimates are becoming finer and more focused on the most critical parameters. The development of this algorithm required the use of several models (LIDAR, wake vortices, atmosphere) and to formulate a number of simplifying assumptions in order to reach a reasonable computational cost. The proposed algorithm was then subjected to a performance evaluation, the interest being focused on the robustness with respect to the different noises altering the measurement, particularly the one related to the atmospheric turbulence, and with respect to the model errors. This evaluation was carried out both on simulated data using simplified parametric models, and on Large Eddy Simulations.The instrumental parameters of LIDAR are potential degrees of freedom to improve the performance of the estimator, in particular for the most critical quantities, that is to say the circulation values. The calculation of the performance of the estimator requiring a significant computational cost, it lends itself poorly for optimization purposes. This is why a study of the influence of the LIDAR parameters on the Cramér-Rao Bound (CRB) was carried out. This study allowed to understand the influence of the instrumental parameters and to reach an optimal configuration for the CRB.

In this thesis, I demonstrate a single­photon Light Detection And Ranging, (LiDAR)system operating at 1550 nm capable of reconstructing 3D environments live withmm resolution at a rate of 400 points per second using eye­safe laser pulses. Thesystem was built using off­-the-­shelf optical components and analysis was performedusing open-­source software. I utilise a single superconducting nanowire single photondetector (SNSPD) with 19 ps time jitter and 85% detection efficiency to achieve a 4 psdepth resolution in live measurements. I also show that by performing slightly moretime costly post analysis of the data it is possible to increase the details and smoothnessof the images. Furthermore, I show that the same LiDAR system and much of the algorithms usedfor 3D LiDAR can be used to perform Optical Time Domain reflectrometry (OTDR)measurements. I demonstrate that the system can identify interfaces between differentrefractive mediums such as fibre to fibre or fibre to air couplings with a depth resolutionof 9 mm along a single line. Using these reflections, I also show that the systemcan identify flaws in optical fibres as well as measure certain characteristics suchas absorption coefficient due to Rayleigh scattering or thermal expansion. Lastly, Idemonstrate that the same OTDR principles used in fibres can be applied to free­s-paceoptical setups and that the system can identify specific optical elements as well asmeasure the quality of the alignment of an optical system. / I detta projekt demonstrerar jag ett enstaka foton Light Detection And Ranging,(LiDAR) system som använder ljus med 1550 nm våglängd som är ofarliga för ögon.Systemet kan återskapa 3D miljöer i realtid med 400 punkter per sekund med mmprecision. Systemet är byggt med kommersiellt tillgängliga komponenter och all dataanalys utfördes med open­source mjukvaran ETA. Jag använder en superconductingnanowire single photon detector, (SNSPD) med 19 ps timing jitter och 85 % effektivitetför att uppnå en precision på 4 ps i mätningarna. Jag visar också att genom utföramer tidskrävande post­analys av datan så är det möjligt att öka upplösningen ochjämnheten i bilderna. Utöver detta visar jag att samma LiDAR system och algoritmer kan användas för attutföra Optical Time Domain reflectrometry, (OTDR) mätningar. Jag visar att systemetkan urskilja olika reflektioner från fiber till fiber och fiber till luft kopplingar. Med hjälpav dessa reflektioner visar jag också att det är möjligt att identifiera brister i optiskafiber samt mäta olika egenskaper av fibern som absorbtions koeffcient eller termiskkontraktion. Slutligen visar jag att samma principer av OTDR som används i fiber kantillämpas till free­-space optiska system och att det är möjligt att identifera olika optiskaelement samt bedömma linjeringen av det optiska systemet.

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Where once the Arctic basin held predominantly old, thick perennial sea ice, it is now increasingly occupied by young, thin seasonal ice. The sea ice surface topography, which affects and is affected by many of the physical processes operating at the interface between ocean, sea ice and atmosphere, is closely related to the age and type of sea ice cover. In this thesis, new methods are presented for measuring and understanding sea ice topography using Light Detection and Ranging (LiDAR) technology. A new technique is presented for parameterizing the micro-scale roughness of sea ice using terrestrial LiDAR. Field, laboratory and numerical experiments have been carried out to test the precision and accuracy of the technique, and calibrations have been developed for correcting field observations of surface roughness for known biases. Results obtained using this technique have been applied in several microwave remote sensing and electromagnetic-wave scattering model studies of snow-covered and melting sea ice. Terrestrial and satellite LiDAR observations are acquired and combined in a further study to examine how sea ice surface topography regulates the melting of ice during the Arctic summer. Observations from a field program in the Canadian Arctic show that minor variations in the roughness of pre-melt sea ice topography can affect significant variations in the melt pond coverage at the ice surface in summer. Numerical simulations are used to develop a quantitative understanding of these findings and, when applied to satellite observations, explain most of the spatial variation in Arctic summer ice melting rates. Results suggest that a recent reduction in sea ice roughness, caused by progressive changes in the type of sea ice resident in the Arctic Ocean, has accelerated the summer melting and decline of the Arctic sea ice cover. / May 2016

More than 54% of the world population lives in urban areas, and this percentage is projected to increase rapidly in future years. This growth significantly affects the hydrological cycle, which translates into social and economic costs due to urban flooding. This thesis develops a procedure to evaluate the current storm water infrastructure using Airborne LiDAR data. This evaluation is essential to mitigate and prevent the effect of floods in urban areas. Airborne LiDAR data provides the elevation data necessary to characterize the elements involved in the storm water system. The processing of this data, digitization, and characterization of the storm drainage system is computed with ArcGIS, Geographic Information System (GIS) software. Scenarios for 4 return periods (2, 10, 25 and 100 years) are modeled using StormCAD in order to evaluate the capacity of the stormwater sewer system in the northwest area of The University of Texas at Austin main campus. The performance of the drainage system might work under strain for a 100-year storm event; therefore, it is suggested to modify the pipe sizes to prevent flooding in the area analyzed. The results indicate that the methodology proposed for evaluating the current conditions of a stormwater drainage system produces valid results, but can be improved using Ground-based LiDAR data. / text

Master of Arts / Department of Geography / Kevin P. Price / Due in large part to changes in land management practices, eastern redcedar (Juniperus virginiana L.), a native Kansas conifer, is rapidly invading onto valuable rangelands. The suppression of fire and increase of intensive grazing, combined with the rapid growth rate, high reproductive output, and dispersal ability of the species have allowed it to dramatically expand beyond its original range. Based on its abundance and invasive nature there is a growing interest in harvesting this species for use as a biofuel. For economic planning purposes, density and biomass quantities for the trees are needed. Three methods are explored for mapping eastern redcedar and quantifying its biomass in Riley County, Kansas. First a comparison of plot-regression versus individual tree based techniques is conducted to determine the optimal approach for characterizing redcedar tree canopy using LiDAR (Light Detection and Ranging). Second a hybrid approach is utilized to characterize redcedar canopy biomass using LiDAR and high-resolution multispectral imagery. Finally, to explore alternative methods of characterizing the three-dimensional structure of redcedar canopy a comparison of “Structure from Motion” photogrammetric techniques and LiDAR is conducted. These methods showed promising results and proved to be useful in the forestry, range management, and bioenergy industries for better understanding the potential of invasive redcedar as a biofuel resource.

Peatlands are unique and important landscape systems, providing valuable ecosystem services such as water and carbon storage, water supply and flood attenuation. They are known to account for more than 10% of the world’s terrestrial carbon store and represent 50 – 70% of the global wetland resource. The UK government’s decision to support the IUCN, UK Peatland Program Commission of Inquiry on Peatlands, recognises the importance and urgency with which action is needed to understand and restore damaged peatland landscapes, and their associated ecosystem services. To meet this need, it is recognised that peatlands in the South West of the UK are important as bio-climatically and functionally marginal peatlands that are undergoing extensive restoration to reinstate key ecological and hydrological function. This thesis aims to improve understanding of the temporal and spatial variability of the ecohydrological structure and function of peatland ecosystems in the South West UK, and will provide the first baseline for the spatially distributed extrapolation of change across larger landscape extents. The research seeks to characterise the structure and function of peatland ecohydrology across multiple spatial and temporal scales. This is accomplished by bringing together remote sensing analyses of ecohydrological structure and function coupled with an integrated and high resolution hydrological monitoring system to characterise the spatial and temporal variability of runoff production and water storage across two headwater catchments. Key outcomes of this research are: 1. The development of novel methods to assess the spatial distribution of near surface hydrology in upland ecosystems using airborne thermal imaging data, 2. Improved understanding of how laser altimetry data can be used to measure the ecohydrology of landscapes more appropriately. 3. An empirical understanding of both the spatial and temporal variability of hydrology across representative sites within the moorlands of the South West UK. The high-resolution monitoring data are the first to describe the hydrological processes operating in these peatlands systems effectively, and provide an insight into how these processes are controlled by the anthropogenic drainage networks that are present throughout this shallow marginal peatland system.