Determination of two dimensional trace gas distributions using tomographic LP-DOAS measurements in the city of Heidelberg, Germany

Tomographic Long path Differential Optical Absorption Spectroscopy (LP-DOAS) allows two and three dimensional determination of trace gas distributions by measuring the average concentration along 10 to 20 intersecting light paths and applying tomographic inversion techniques. In this thesis such a setup was developed and applied for the first time to determine the horizontal distribution of several trace gases in the open atmosphere. The measurements took place in the city of Heidelberg, Germany from 2005 to 2007 and focused on the trace gases NO2, SO2, O3, HCHO and HONO, which play a major role in the polluted atmosphere. The setup consisted of three Multi Beam LP-DOAS instruments and 20 retro reflector arrays all installed on different buildings in the city. The 20 realised intersecting light paths covered an area of 4 × 4 km² with different emission sources. The retrieved horizontal trace gas distributions had a temporal resolution of up to 15 minutes with best results for NO2, SO2 and O3. The highest trace gas concentrations (except for O3) and spatial variations arose during low wind situations. Emission sources varying in space and time could be distinguished and identified mainly as emissions from traffic (NO2 with O3 depletion) and power plants / industry (SO2). Several insights into chemical processes in the atmosphere could be gained by studying the interrelationship of the measured trace gases. HONO, for example, displayed much lower spatial variability than NO2 and was thus not directly emitted by the same source but rather formed in heterogeneous reactions. Transport processes of plumes were also investigated

Development of a Tomographic Atmospheric Monitoring System based on Differential Optical Absorption Spectroscopy

The aim of this thesis is to describe the design and development of a proof of concept for a commercially viable large area atmospheric analysis tool, for use in trace gas concentration mapping and quanti cation. Atmospheric monitoring is a very well researched eld, with dozens of available analytical systems and subsystems. However, current systems require a very important compromise between spatial and operational complexity. We address this issue asking how we could integrate the Di erential Optical Absorption Spectroscopy (DOAS) atmospheric analysis technique in a Unmanned Aerial Vehicle (UAV) with tomographic capabilities. Using a two-part methodology, I proposed two hypotheses for proving the possibility of a miniaturised tomographic system, both related to how the spectroscopic data is acquired. The rst hypothesis addresses the projection forming aspect of the acquisition, its matrix assembly and the resolution of the consequent equations. This hypothesis was con rmed theoretically by the development of a simulation platform for the reconstruction of a trace gas concentration mapping. The second hypothesis deals with the way in which data is collected in spectroscopic terms. I proposed that with currently available equipment, it should be possible to leverage a consequence of the Beer-Lambert law to produce molecular density elds for trace gases using passiveDOAS. This hypothesiswas partially con rmed, with de nite conclusions being possible only through the use of complex autonomous systems for improved accuracy. This work has been a very important rst step in the establishment of DOAS tomography as a commercially viable solution for atmospheric monitoring, although further studies are required for de nite results. Moreover, this thesis has conducted to the development of a DOAS software library for Python that is currently being used in a production environment. Finally, it is important to mention that two journal articles were published from pursuing this work, both in important journals with Impact Factors over 3.0.Era o objectivo deste trabalho descrever o processo de desenho e implementação de uma prova de conceito para um sistema de avaliação atmosférica comercialmente viável, para uso no mapeamento das concentrações de compostos traço na atmosfera. A avaliação atmosférica é um campo muito estudado, estando no presente momento disponíveis para instalação diversos sistemas e subsistemas com estas capacidades. No entanto, é marcante o compromisso que se veri ca entre a resolução espacial e a complexidade operacional destes equipamentos. Nesta tese, desa o este problema e levanto a questão sobre como se poderia desenvolver um sistema com os mesmos ns, mas sem este premente compromisso. Usando uma metodologia a duas partes, proponho duas hipóteses para comprovar a exequibilidade deste sistema. A primeira diz respeito à formação da matriz tomográ ca e à resolução das equações que dela derivam e que formam a imagem que se pretende. Con rmei esta hipótese teoricamente através do desenvolvimento de uma plataforma de simulação para a reconstrução tomográ ca de um campo de concentrações fantoma. A segunda é dirigida a aquisição de dados espectroscópicos. Proponho que com o material presentemente disponível comercialmente, deverá ser possível aproveitar uma consequência da lei de Beer-Lambert para retirar os valores de concentração molecular de gases traço na atmosfera. Foi apenas possível validar esta hipótese parcialmente, sendo que resultados mais conclusivos necessitariam de equipamentos automatizados dos quais não foi possível dispôr. No nal, este trabalho constitui um importante primeiro passo no estabelecimento da técnica de DOAS tomográ co como uma alternativa comercialmente viável para a análise atmosférica. Ademais, o desenvolvimento desta tese levou à escrita de uma biblioteca em Python para análise de dados DOAS actualmente usada em ambiente de produção. Por m, importa realçar que dos trabalhos realizados no decorrer da tese foram publicados dois artigos em revistas cientí cas com Impact Factor acima de 3

Comprehensive Detection of Gas Plumes from Multibeam Water Column Images with Minimisation of Noise Interferences

Multibeam echosounder systems (MBES) can record backscatter strengths of gas plumes in the water column (WC) images that may be an indicator of possible occurrence of gas at certain depths. Manual or automatic detection is generally adopted in finding gas plumes, but frequently results in low efficiency and high false detection rates because of WC images that are polluted by noise. To improve the efficiency and reliability of the detection, a comprehensive detection method is proposed in this paper. In the proposed method, the characteristics of WC background noise are first analyzed and given. Then, the mean standard deviation threshold segmentations are respectively used for the denoising of time-angle and depth-angle images, an intersection operation is performed for the two segmented images to further weaken noise in the WC data, and the gas plumes in the WC data are detected from the intersection image by the morphological constraint. The proposed method was tested by conducting shallow-water and deepwater experiments. In these experiments, the detections were conducted automatically and higher correct detection rates than the traditional methods were achieved. The performance of the proposed method is analyzed and discussed

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 235)

This publication is a cummulative index to the abstracts contained in Supplements 223 through 234 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included -- subject, personal author, corporate source, foreign technology, contract number, report number and accession number

Protecting the Diversity of the Depths: Strengthening the International Law Framework

It is only in recent decades that marine scientific research has begun to reveal the true physical characteristics and resource potential of the open ocean and deep seabed beyond national jurisdiction. A combination of factors such as the depletion of inshore fish stocks and an increase in global maritime trade has led to greater usage of the vast maritime area beyond the territorial sea and exclusive economic zone limits of the coastal states. Human activities in this area of the ocean, which covers approximately 50% of the world’s surface, have expanded to include bioprospecting, exploration for deep seabed minerals, more sophisticated marine scientific research and deep sea tourism. This rise in human activities beyond the offshore zones of coastal states poses actual and potential threats to the physical characteristics and biodiversity of the open ocean and deep sea environments. Arbitrary human intrusions into this largely unexplored marine domain have the potential to harm the intricate links between complex marine ecosystems and to erode components of marine biodiversity. This thesis examines the global and regional provisions which have been put in place to regulate the environmental impacts of human activities that occur beyond national jurisdiction. An analysis of these instruments and their implementation reveals that the current international law framework provides only minimal levels of protection for the marine environment beyond national jurisdiction. It explores several options based on the 1982 United Nations Convention on the Law of the Sea (LOSC) and the 1992 Convention on Biological Diversity (CBD) to establish a cohesive environmental protection system for the marine environment beyond national jurisdiction

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion