Neste trabalho são apresentados os resultados do estudo e desenvolvimento dos parâmetros de projeto de um radiômetro solar multiespectral (RSME), baseado em Filtros de Interferência Variável (FIV) de banda-passante que incorpora uma camada ressoante de Fabry-Perot, inclinada em forma de cunha, sintonizável dentro da área opticamente ativa do FIV, aplicável ao sensoriamento ambiental e de aerossóis. Foi apresentada a teoria proposta para a simulação, projeto e deposição pelo método interativo (simulações associada às avaliações de deposições). O FIV foi parametrizado para o RSME, mas pode atender outras aplicações em sensores multicanais e multiespectrais. A construção dos FIV exigiu estudos e adaptações das técnicas clássicas de deposição de filmes finos e de microeletrônica, foi utilizada a PVD/E-Beam. É apresentado um estudo e o emprego de simulações matemáticas e softwares, aplicáveis a FI convencionais correlatas aos FIVs. Estes softwares foram aplicados e avaliados em relação ao projeto dos FIV. Avaliamos a técnica empregada que produz a inclinação na espessura dos FIVs em uma monocamada de 600 nm com um Perfilômetro do LME. Os FIVs caracterizados opticamente com espectrofotômetros, apresentam uma área opticamente ativa de varredura de 120,5 nm no espectro eletromagnético, entre os canais 475,5 nm a 596 nm, pertencentes a 17,3 mm de extensão do FIV. O FIV é um dispositivo óptico projetado com espessura em cunha provocando a resposta espectral linear para a transmitância, com uma taxa de 6,97 nm/mm na sua extensão. Foi proposto que os FIVs caracterizados em conjunto com PD de um PDA, difusor e lente, formem um conjunto detector conectado a um módulo de pré-processamento e coleta de dados (módulo eletrônico) formando assim o RSME parametrizado. O RSME proposto foi avaliado utilizando o FIV02 que opera numa faixa opticamente ativa entre (600 nm a 715 nm), um PDA modelo TSL1401 com 128 PD e um microcontrolador Arduino UNO para o gerenciamento da detecção. Os resultados apontam que o instrumento faz medições equivalentes a outro espectrofotômetro de referência quando medindo um feixe monocromático em 655,4 nm, mas com resolução mais estreita de 0,13 nm por canal. Foi apontada também a necessidade de instrumentação dedicada para outras caracterizações ópticas dos FIV, do conjunto detector do RSME e para a sua calibração. / This paper presents the results of the study and development of the design parameters of a Multi-Spectral Solar Radiometer (MSSR), based on Variable Interference Filter (VIF) pass-bad which incorporates a resonant layer Fabry-Perot inclined in form wedge, tunable within the optically active area of VIF, applicable to enviro nmental sensing and aerosols. The theory proposed was presented for the simulation, design and deposition by interactive method (associated with reviews of depositions simulations). The VIF was parameterized for the MSSR, but can serve other applications in multi-channel and multispectral sensors. The construction of VIF required studies and adaptations of the classic techniques of thin film deposition and microelectronic, was used the PVD / E-Beam. A study and the use of mathematical and simulation software, related to VIFs applicable to conventional IF appears. This software were applied and assessed in relation to the design of VIF. We evaluate the technique that produces the slope in the thickness of VIFs in a monolayer of 600 nm with a LMEs Surface Profiler. The VIFs characterized optically with spectrophotometers, can present an optically active area scanning 120,5 nm of the electromagnetic spectrum between channels 475,5 nm to 596 nm, belonging to 17,3 mm extension of VIF. FIV is an optical device designed with wedge-shaped thickness resulting in the linear transmittance for the spectral response with a 6,97 nm/mm in extension rate. It was proposed that VIFs characterized together with PD of a PDA, diffuser and lens form a detector module connected to a set of pre-processing and data collection (electronic module) thus forming the parameterized MSSR. The proposed MSSR was assessed using the VIF02 which operates a range of optically active (600 nm to 715 nm), a PDA model TSL1401 with PD 128 and Arduino UNO microcontroller to manage the detection. The results indicate that the instrument is equivalent to other reference spectrophotometer measurements, when measuring a monochromatic beam at 655,4 nm, but with narrower 0,13 nm resolution by channel. It was also pointed out the necessity of dedicated instrumentation for optical characterizations of other VIF MSSR detector assembly and the calibration.

In this thesis, we have presented a systematic analysis of the change of cloud properties due to variation in aerosol concentration over Indian region using satellite observations, and Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) simulations. The Tropical Rainfall Measurement Mission (TRMM) based Microwave Imager (TMI) estimates (2A12) have been used to compare and contrast the characteristics of cloud liquid water and ice over the Indian land region and the surrounding oceans, during the pre-monsoon (May) and monsoon (June–September) seasons. Based on the spatial homogeneity of rainfall, we have selected five regions for our study (three over ocean, two over land). In general, we find that the mean cloud liquid water and cloud ice content of land and oceanic regions are different, with the ocean regions showing higher amount of CLW. A comparison across the ocean regions suggests that the cloud liquid water over the or graphically influenced Arabian Sea (close to the Indian west coast) behaves differently from the cloud liquid water over a trapped ocean (Bay of Bengal) or an open ocean (Equatorial Indian Ocean). Specifically, the Arabian Sea region shows higher liquid water for a lower range of rainfall, whereas the Bay of Bengal and the Equatorial Indian Ocean show higher liquid water for a higher range of rainfall. Apart from geographic differences, we also documented seasonal differences by comparing cloud liquid water profiles between monsoon and pre-monsoon periods, as well as between early and peak phases of the monsoon. We find that the cloud liquid water during the lean periods of rainfall (May or June) is higher than during the peak and late monsoon season (July-September) for raining clouds over central India. However, this is not true over the ocean. As active and break phases are important signatures of the monsoon progression, we also analyzed the differences in cloud liquid water during various phases of the monsoon, namely, active, break, active-to-break (a2b) and break-to-active (b2a) transition phases. We find that the cloud liquid water content during the b2a transition phase is significantly higher than that during the a2b transition phase over central India. We speculate that this could be attributed to higher amount of aerosol loading over this region during the break phase. We lend credence to this aerosol-liquid water/rain association by comparing the central Indian cloud liquid water with Southeast Asia (where the aerosol loading is significantly smaller) and find that in the latter region, there are no significant differences in cloud liquid water during the different phases of their monsoon. The second part of our study involves evaluating the ability of the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to simulate the observed variation of cloud liquid water and rain efficiency. We have used no chemistry option, and the model was run with constant aerosol concentration. The model simulations (at 4.5 km resolution) are done for the month of June–July 2004 since this period was particularly favorable for the study of an active–break cycle of the monsoon. We first evaluate the sensitivity of the model to different parameterizations (microphysical, boundary layer, land surface) on the simulation of rain over central India and Bay of Bengal. This is done to identify an “optimal” combination of parameterizations which reproduces the best correlation with observed rain over these regions. In this default configuration (control run), where the aerosol concentration is kept constant throughout the simulation period, the model is not able to reproduce the observed variations of cloud liquid water during the different phases of an active-break cycle. To this end, we proceeded to modify the model by developing an aerosol-rain relation, using Aerosol Robotic Network (AERONET) and TRMM 3B42 data that realistically captures the variation of aerosol with rain. It is worth highlighting here that our goal was to primarily isolate the indirect effect of aerosols in determining the observed changes in cloud liquid water (CLW) during the active-break phases of the Indian monsoon, without getting into the complexity of a full chemistry model such as that incorporated in WRF-Chem. Moreover, the proposed modification (modified run) is necessitated by the lack of realistic emission estimates over the Indian region as well as the presence of inherent biases in monsoon simulation in WRF. The main differences we find between the modified and control simulations is in the mean as well as spatial variability of CLW. We find that the proposed modification (i.e., rate of change of aerosol concentration as a function of rain rate) leads to a realistic variation in the CLW during the active-break cycle of Indian monsoon. Specifically, the peak value of CLW in the b2a (a2b) phase is larger (smaller) in the modified as compared to the control run. These results indicate a stronger change in CLW amount in the upper levels between the two transition phases in the modified scheme as compared to the control simulation. More significantly, we also observe a change in sign at the lower levels of the atmosphere, i.e., from a strong positive difference in the control run to a negative difference in the modified simulation, similar to that observed. Additionally, we investigated the impact of the proposed modification, via CLW changes, on cloud coverage, size of clouds and their spatial variability. We find that the transformation of optically thin clouds to thick clouds during the break phase was associated with larger cloud size in modified compared to the control simulation. Moreover, the higher rate of decay of the spatial variability of CLW with grid resolution, using the modified scheme, suggests that clusters of larger clouds are more in the modified compared to control simulation. Taken together, the interactive aerosol loading proposed in this thesis yields model simulations that better mimic the observed CLW variability between the transition phases.

Epidemiological research around the world has shown that exposure of urban populations to fine microparticles (PM2.5) suspended in air from, among other things, car combustion, is responsible for many cases of lung and cardiovascular disease and even mortality. However, most of these studies examine urban centers as ensembles without considering that population exposure to microparticles is not homogeneous across an urban space. For example, individuals living near major arterial roads are much more exposed to microparticles than others living in low traffic neighborhoods. Unfortunately, ground stations measuring PM2.5 are few and far between to generate accurate microparticle concentration maps at fine scales. One way to spatialize information on microparticle concentrations is to introduce remotely sensed images that allows to calculate an optical parameter of aerosols, their optical depth. The use of medium-to-fine-resolution images is not common in this area. So, we wanted to look at their potential. Tests with hyperspectral and multispectral images at these resolutions have shown that optical depth can be estimated with enough accuracy. The AODFinder software developed for this purpose performs well. Unfortunately, the small sample of AOD values and PM2.5 concentration measurements did not allow us to conclude on the possibility of using AOD as a proxy for PM2.5 and thus on the possibility of refining microparticle monitoring at the local level. / Des recherches épidémiologiques à travers le monde ont mis en évidence que l’exposition des populations urbaines aux microparticules fines (PM2.5) en suspension dans l’air provenant, entre autres, de la combustion automobile, est à l’origine des nombreux cas des maladies pulmonaires et cardiovasculaires et même des cas de mortalité. Cependant, la plupart de ces études examinent les centres urbains comme des ensembles sans tenir compte que l’exposition des populations aux microparticules n’est pas homogène à travers un espace urbain. À titre d’exemple, les individus demeurant à proximité de grandes artères routières sont beaucoup plus exposés aux microparticules que d’autres demeurant dans des quartiers de faible circulation. Malheureusement, les stations terrestres de mesure des PM2.5 sont peu nombreuses pour permettre de générer des cartes de concentration des microparticules précises à des échelles fines. Un moyen pour spatialiser l’information sur les concentrations des microparticules est d’introduire l’imagerie de télédétection qui permet de calculer un paramètre optique des aérosols, leur profondeur optique. L’utilisation des images à résolution moyenne à fine n’est pas chose courante dans ce domaine. Ainsi nous avons voulu examiner leur potentiel. Les tests avec des images hyperspectrale et multispectrale à ces résolutions ont montré que la profondeur optique peut être estimer avec suffisamment de précision. Le logiciel AODFinder développé à cette fin se comporte bien. Malheureusement le faible échantillon des valeurs de AOD et des mesures des concentrations des PM2.5 ne nous a pas permis de se prononcer sur la possibilité d’utiliser le AOD comme proxy des PM2.5 et ainsi sur la possibilité de raffiner le monitoring des microparticules à l’échelle locale.

In this thesis, we present the Monte Carlo study of two prototypes of tele- scopes for the Cherenkov Telescope Array (CTA) observatory, followed by the first data analysis partially using our reconstruction pipeline based on Random Forests. The Monte Carlo model of the SST-1M prototype is created and val- idated by comparison with data. Using the precise Monte Carlo models, we evaluate the performance of the SST-1M and LST-1 prototypes, working so-far in mono-regime as standalone telescopes, resulting in their energy and angular resolution, and the differential sensitivity. We also present an analysis of the data from the first two Crab Nebula observation campaigns conducted with the LST-1 telescope. In the last part of the thesis, we present a study of aerosol optical depth of the atmosphere above both future sites of the CTA observa- tory, retrieved from photometric measurements of Sun/Moon photometers. We focus on the photometer in-situ calibration for nocturnal measurements and introduce corrections to minimize systematic shifts between diurnal and noc- turnal measurements. Using the developed methods, we present the aerosol characterization of both CTA sites based on the photometric data. 1

No description available.

Aerosols are small, micrometer-sized particles, whose optical effects coupled with their impact on cloud properties is a source of large uncertainty in climate models. While their radiative forcing impact is largely of a cooling nature, there can be significant variations in the degree of their impact, depending on the size and the nature of the aerosols. The radiative and optical impact of aerosols are, first and foremost, dependent on their concentration or number density (an extensive parameter) and secondly on the size and nature of the aerosols (intensive, per particle, parameters). We employed passive (sunphotmetry) and active (backscatter lidar) measurements to retrieve extensive optical signals (aerosol optical depth or AOD and backscatter coefficient respectively) and semi-intensive optical signals (fine and coarse mode OD and fine and coarse mode backscatter coefficient respectively) and compared the optical coherency of these retrievals over a variety of aerosol and thin cloud events (pollution, dust, volcanic, smoke, thin cloud dominated). The retrievals were performed using an existing spectral deconvolution method applied to the sunphotometry data (SDA) and a new retrieval technique for the lidar based on a colour ratio thresholding technique. The validation of the lidar retrieval was accomplished by comparing the vertical integrations of the fine mode, coarse mode and total backscatter coefficients of the lidar with their sunphotometry analogues where lidar ratios (the intensive parameter required to transform backscatter coefficients into extinction coefficients) were (a) computed independently using the SDA retrievals for fine mode aerosols or prescribed for coarse mode aerosols and clouds or (b) computed by forcing the computed (fine, coarse and total) lidar ODs to be equal to their analog sunphotometry ODs. Comparisons between cases (a) and (b) as well as the semi-qualitative verification of the derived fine and coarse mode vertical profiles with the expected backscatter coefficient behavior of fine and coarse mode aerosols yielded satisfactory agreement (notably that the fine, coarse and total OD errors were <~ sunphotometry instrument errors). Comparisons between cases (a) and (b) also showed a degree of optical coherency between the fine mode lidar ratios.