Solar-pumped laser Final report

Solar pumped modulated laser to generate coherent radiation at optical wavelengths for long range, real time television data transmissio

Weekly synoptic analyses 5-, 2-, and 0.4- millibar surfaces for 1966

Meteorological rocketsonde and high level rawinsonde synoptic data analysi

Characteristics, weather scenario and statistics of thunderstorm outflows based on measured data

Wind is the most destructive natural phenomenon: 70% of damage and death caused by nature in the world comes from wind. And extreme winds such as typhoons, tornadoes and thunderstorms are crucial for structural damage. Inside, during a thunderstorm, the transient downdraft that impinges on the ground produces radial outflows that can produce strong transient wind, which is the main cause of the collapse of tall structures such as transmission tower, besides one of the threat to human life and property security, for instance, the accident of transmission line towers in Ontario, Canada in August 2006 and "Oriental star" sinking in China in June, 2015 and so on. The study of thunderstorm outflows and their loading and response of structures already become a key topic in modern wind engineering. Despite this, the understanding, the representation and the modeling of thunderstorm outflows are still full of uncertainties and problems to be clarified. This happens because the complexity of the thunderstorm outflows makes it difficult to establish physically realistic and simple engineering schemes, their short duration and small size means few data are available, and a large gap exists between wind engineering and atmospheric science. It follows that the wind loading of structures is still evaluated by the Davenport\u2019s model for extra-tropical cyclones without any concern for the real nature and the properties of the meteorological event that causes the loading. This is nonsense because extra-tropical cyclones and thunderstorm outflows are different phenomena that need separate assessments. To overcome these limits, this PhD thesis carries out a deep research mainly on the characteristics of thunderstorm outflow according to wind field measurement and meteorological data based on a thunderstorm catalogue created extracted from a mixed climate, which mainly contains the proposal of more reasonable directional decomposed approach of thunderstorm outflow signal, the properties of thunderstorm related to wind loading on structures, the comprehensive analysis of field measurements and weather scenarios related to thunderstorms, the extreme wind speed distribution in a mixed wind climate and the preliminary study of the crucial question if thunderstorms in different areas have similar properties. The major contents and achievements are summarized as follows: Firstly, measurements for up to 6 years related to 14 high-sampling rate anemometers of the monitoring network in the Northern Mediterranean ports are analyzed. Three intense phenomena, namely extra-tropical cyclones, thunderstorm outflow, and intermediate events are separated successfully by a semi-automatic procedure. The results lead to a wide dataset of 277 wind velocity records characterized by strong transient properties and labeled by thunderstorm outflow, which are catalogued into three families, named 10 minutes, 1 hour and 10 hours, according to the different time-scale of the gust front passage, and fundamental for the subsequent study. Analyses are then executed to extract the parameters of major interest for evaluating the wind loading effects of structures. And a novel directional decomposition strategy is formulated here, which makes it possible to analyse quantitatively the directional shift of thunderstorm outflows, makes the study of thunderstorm outflows and synoptic winds fully coherent and is strategic to perform directional analyses of the dynamic behaviour of structures in terms of alongwind and crosswind response. Then this strategy is applied to thunderstorm records comparing with the classical decomposition approach and furnishing a comprehensive statistical characterization. While the general analysis in wind engineering has a shortcoming that it misses the knowledge of the weather scenarios that occur during events classified as thunderstorms, without recognizing their actual meteorological nature. In order to take the first step towards filling this gap, a typical thunderstorm downburst and three events, each one representative of the corresponding class of duration, detected by our network are investigated from the meteorological point of view to represent a first step and a pilot attempt in this direction. The results obtained bring new insights into a thunderstorm\u2019s onset and detection in the Mediterranean, its evolution at the local scale, and possible connections to specific synoptic-scale weather conditions. Design wind speeds based on the statistical analysis of conventional extreme mean wind speed data in a mixed wind climate may prove to be imprecise and unsafe due to the occurrence of intense, small and rapid extreme wind events such as thunderstorm outflows. Considering the continuous records registered in two Port areas of the monitoring network, a preliminary but representative analysis of the extreme wind speed distribution is carried out in this mixed wind climate area frequently struck by thunderstorms. Results show that wind speeds with high return period are always related to thunderstorm outflows. It proves that gathering the ensemble of all extreme values into a single set and the analyses of the local wind climate ignoring thunderstorms may lead to underestimating the extreme wind speed. At the end of the research, this analysis procedure is applied to the 5-year data from the 9 anemometers installed at different heights on Beijing 325m high meteorological tower to study the characteristics of thunderstorms in the Beijing urban area, to compare these with northern Mediterranean ones and to understand if thunder-storms in different areas have similar properties. In addition, the property of the mean wind speed profile and coherent function of thunderstorms are described, which provides a reference for the simulation of thunderstorm signal. Hope this thesis could make some contributions to step further research on thunderstorm-resistant design for building structures

A method to reconstruct flood scenarios using field interviews and hydrodynamic modelling: application to the 2017 Suleja and Tafa, Nigeria flood

Abstract The scarcity of model input and calibration data has limited efforts in reconstructing scenarios of past floods in many regions globally. Recently, the number of studies that use distributed post-flood observation data collected throughout flood-affected communities (e.g. face-to-face interviews) are increasing. However, a systematic method that applies such data for hydrodynamic modelling of past floods in locations without hydrological is lacking. In this study, we developed a method for reconstructing plausible scenarios of past flood events in data-scarce regions by applying flood observation data collected through field interviews to a hydrodynamic model (CAESAR-Lisflood). We tested the method using 300 spatially distributed flood depths and duration data collected using questionnaires on five river reaches after the 2017 flood event in Suleja and Tafa region, Nigeria. A stepwise process that aims to minimize the error between modelled and observed flood depth and duration at the locations of interviewed households was implemented. Results from the reconstructed flood depth scenario produced an error of ± 0.61 m for all observed and modelled locations and lie in the range of error produced by studies using comparable hydrodynamic models. The study demonstrates the potential of utilizing interview data for hydrodynamic modelling applications in data-scarce regions to support regional flood risk assessment. Furthermore, the method can provide flow depths and durations at houses without observations, which is useful input data for physical vulnerability assessment to complement disaster risk reduction efforts

Genesis and distribution of lithium enriched pore brines at the Salar de Uyuni, Bolivia

With a size of ~10,000 km² the Salar de Uyuni is the largest salt lake in the world. It is located at a height of 3,653 m a.s.l. in the southern part of the Bolivian Altiplano, an endorheic high plateau separating the Eastern and Western cordillera of the Andes. The salt flat is characterized by an alternating sequence of evaporate layers mainly consisting of halite and lacustrine mud layers up to a depth of at least 220 m, whereby the stratification is ascribed to the alternation of dry and humid climatic phases during the Quaternary. With estimated 7 Mio tonnes in brine, the salt lake is considered the world’s largest Li deposit. Knowledge About genesis and distribution of Li is essential for the possible extraction of Li and other valuable elements from the brine in a commercial scale, which is the driving force for the Investigation of hydrochemical properties of the Salar de Uyuni. Practical work comprised the sampling of brines from drilled wells and along transects, salts from the surface, sampling of streams, rocks and sediments in the catchment, as well as chemical and isotopical analyses. The surface catchment, delineated with ArcGIS, has a size of 63,000 km² and is mainly characterized by volcanic deposits as ignimbrites, and unconsolidated sediments, salt deposits and lacustrine material in widespread flood plains. The pores of the upper salt crust, which shows a varying thickness of 2-11 m, are filled with a saturated NaCl brine rich in Mg, K, Li and B. The distribution of Li along the salt lake is inhomogeneous, with two regions of significantly higher concentrations up to 1.5 g/L in the southern part near the delta of the main inflow Río Grande and in the northern part, compared to an average of 0.3-0.4 g/L in brine. The age of brines from the upper salt crust was determined to 6,200 - 13,340 years, corresponding in age to the surrounding evaporates and showing a stable stratification with depth. However, a local mixing of the brine with freshwater feeding from groundwater Aquifers especially near the shore of the salar was observed by the analysis of δ2H and δ18O in the brines. The distribution of stable isotopes also shows the strong influence of evaporation, even smaller tributaries feeding the Río Grande are enriched in heavy isotopes of H and O. Element to bromine ratios in the brine showed that Li, K and Mg are not removed from solution by the formation of precipitates, but are rather released from clay minerals by ion exchange leading to their enrichment in the pore brine. Analyzed rocks, mostly of rhyolitic and dacitic type, show moderate lithium concentrations in the range of 4 to 37 mg/kg. Different types of digestion revealed that rock types occurring in the Salar de Uyuni catchment are a substantial supplier of lithium by the intensive physical and chemical weathering due to the specific environmental conditions. Increased Lithium concentrations in rock and sediment samples from the volcano flanks south of the salar indicate, that the southern catchment is the main supplier of lithium to the salt lake. The enrichment of lithium could also be observed by the analysis of superficial salts from the upper crust. Salt efflorescences are significantly enriched regarding Li, K, Mg and other Ions compared to the surface within the polygons. The enrichment of Li in brine occurs all-Season along shrinkage cracks at polygon borders, where brine rises up, water evaporates and NaCl precipitates, leaving a solution even more concentrated in Li and other solutes as Br, B, K and Mg. In conclusion, the accumulation of lithium in the brine of the Salar de Uyuni results from the combination of various site-specific circumstances, which are analyzed and discussed in the present thesis.Mit einer Größe von ~10.000 km² ist der Salar de Uyuni der größte Salzsee der Welt. Er befindet sich auf einer Höhe von 3.653 m im Süden des bolivianischen Altiplano, einer abflusslosen Hochebene zwischen der Ost- und Westkordillere der Anden. Der Salzsee besteht bis zu einer Tiefe von mind. 220 m aus einer Wechselfolge evaporitischer Schichten (hauptsächlich halitisch) und lakustrinen Tonschichten, wobei die Schichtung auf den Wechsel von trockenen und feuchten klimatischen Phasen während des Quartärs zurückzuführen ist. Mit einer geschätzten Menge von 7 Mio. t gilt der Salzsee als die gegenwärtig größte Li-Ressource der Welt. Das Wissen über Genese und Verteilung von Li ist grundlegend für eine mögliche Gewinnung von Li und anderen Elementen in kommerziellem Maßstab, worin sich die Motivitation für die Untersuchung hydrochemischer Eigenschaften des Salar de Uyuni begründet. Praktische Tätigkeiten umfassten die Probenahme von Solen aus eigens gebohrten Brunnen und entlang von Transekten, die Entnahme von Oberflächensalzen, die Beprobung von Zuflüssen, Gesteinen und Sedimenten im Einzugsgebiet, sowie deren chemische und isotopische Analytik. Das oberflächliche, mittels ArcGIS ermittelte Einzugsgebiet, weist eine Größe von 63.000 km² auf und besteht hauptsächlich aus vulkanischen Gesteinen wie Ignimbriten und unverfestigten Ablagerungen, Salzausblühungen und lakustrinen Sedimenten in ausgeprägten Überschwemmungsebenen. Die Poren der obersten, zwischen 2 und 11 m mächtigen Salzschicht, sind mit einer an NaCl gesättigten Salzlösung, die reich an Mg, K, Li und B ist, gefüllt. Die inhomogene Verteilung von Li im Salzsee weist zwei Bereiche signifikant erhöhter Konzentrationen von bis zu 1,5 g/L auf, und zwar im südlichen Einmündungsbereich des Hauptzuflusses Río Grande und im Nordosten etwa 20 km von der Küste entfernt, verglichen mit einem durchschnittlichen Gehalt von 0,3-0,4 g/L in der Sole. Das Alter der Solen der obersten Salzkruste wurde auf 6.200 – 13.340 Jahre bestimmt, was dem Alter der umgebenden Evaporite entspricht und eine stabile Schichtung aufweist. Allerdings weist die Analytik von δ2H und δ18O auch auf eine lokale Vermischung der Sole mit Frischwasser aus ufernahen Aquiferen hin. Die Verteilung der stabilen Isotope δ²H und δ18O deutet auf einen signifikanten Einfluss der Verdunstung auf die Entwicklung der Porenlösung hin, denn auch kleinere Zuflüsse zum Salar sind angereichert an 2H und 18O. Das Verhältnis verschiedener Elemente zu Brom zeigt, dass Li, K und Mg weniger durch die Ausfällung von Salzen aus der Lösung entfernt, sondern eher durch Ionenaustausch aus Tonmineralen freigesetzt und folglich in der Sole angereichert werden. Die analysierten Gesteine, hauptsächlich rhyolitischen und dazitischen Typs, weisen moderate Lithiumkonzentrationen von 4 – 37 mg/kg auf. Die Anwendung verschiedener Aufschlüsse zeigte, dass die im Einzugsgebiet des Salar de Uyuni vorkommenden Gesteinstypen aufgrund der intensiven physikalischen und chemischen Verwitterung unter den spezifischen Umweltbedingungen eine wesentliche Quelle des Lithiums im Salzsee sind. Erhöhte Li-Konzentrationen in Gesteinen und Sedimenten der vulkanischen Flanken südlich des Salars deuten auf das südliche Einzugsgebiet als hauptsächlichen Zulieferer für Li hin. Die Anreicherung von Li wurde auch mittels der Untersuchung der Salze der obersten Kruste bestätigt. Im Vergleich zur Oberfläche innerhalb der Polygone sind die Salzausblühungen entlang der Polygonränder signifikant an Li, K, Mg und anderen Ionen angereichert. Die Anreicherung von Li geschieht ganzjährig entlang der Schrumpfungsrisse an Polygonrändern, indem die Sole durch kapillare Kräfte aufsteigt, Wasser verdunstet und NaCl ausfällt. Schließlich bleibt eine an Li und anderen Ionen wie Br, B, K und Mg noch stärker aufkonzentrierte Lösung zurück. Schlussfolgernd resultiert die Akkumulation von Lithium in der Porenlösung aus der Kombination zahlreicher standortspezifischer Faktoren, welche innerhalb der vorliegenden Arbeit untersucht und bewertet wurden

Remote sensing applications to hydrologic modeling in the southern Sierra Nevada and portions of the San Joaquin Valley, volume 1

The author has identified the following significant results. Characteristics of LANDSAT MSS imagery present problems in using satellite radiation measurements to estimate the shortwave albedo of an alpine snow cover. Every 15 minute USGS quadrangle contains over 100,000 pixels which poses a computation problem if each pixel is to be evaluated individually. The sampling interval may be sufficiently great to mask some effects of terrain and vegetation on reflectance. Three frames of LANDSAT imagery are needed for complete coverage of the study area, yet less than one third of the area coverage from each frame covers an area of interest. Because of distortions inherent in the imagery, information regarding spacecraft altitude, attitude, and position must be statistically derived with respect to ground control points in the image whose geodetic locations are known. An inspection of shade points indicates that up to one third of the most heavily snow covered areas may saturate in bands 4 through 6. LANDSAT's 9 day repeat cycle is not optimum for snow cover reflectance modeling because the most pronounced changes in albedo occur most nearly following a new snowfall. Such a snowfall, occurring between overpasses, is inadequately represented by extrapolation from the previous overpasses