Studying the Indian monsoon variability over the Early Holocene and Common Era in high resolution with numerical reconstructions based on planktic foraminifera

The Indian Monsoon is an impressive seasonal climate phenomenon and an important driver for the inter-hemispheric transport of heat and moisture. Due to the strongly seasonal character, the Indian Monsoon is subdivided into the Indian Summer Monsoon (ISM), which is most intense from July to September, and the In- dian Winter Monsoon (IWM), which generally occurs from January to March. The ISM and accompanied precipitation is an important source of freshwater, because it brings most of the annual rainfall to India and its neighbouring countries. To assess the future development of ISM variability is therefore of utmost importance for the economic prosperity and agricultural development in one of the worlds’ most densely populated regions. The understanding of potential ISM response to different scenarios of future climate changes requires detailed knowledge of the monsoon history. It is therefore vital to study archives of past ISM variability on time scales that are important for societal development, i.e. years to decades. Furthermore, our understanding of the monsoon system and its potential driving forces is incomplete without better knowledge of IWM variability. Due to the extreme seasonality of the Indian Monsoon, induced by the opposing direction of the prevailing surface winds, the monsoons exert a strong influence on the hydrography of the Arabian Sea. The ISM is characterized by intensive upwelling, associated with surface water cooling and elevated surface water productivity in the northwestern Arabian Sea. The dry and cold winds of IWM are associated with evaporative cooling of surface waters and convective deepening of the mixed-layer, which leads to nutrient entrainment and elevated surface water productivity in the northeastern part of the basin. High primary productivity and reduced ventilation of intermediate waters leads to strong and stable oxygen deficient conditions at mid-depth. The conditions within the oxygen minimum zone (OMZ) favor the removal of nitrogen via reduction of biologically available inorganic nitrogen to nitrous oxide (N2O), which is an important greenhouse gas. This thesis focuses on the reconstruction of both seasonal monsoon components throughout three relatively short time slices of the Holocene epoch in ultra high resolution using a collaborative multi-proxy approach. In order to study past changes of the monsoon seasons, three hemipelagic sediment cores from the Arabian Sea region were studied. One core from the northern Oman margin is deposited under the dominant influence of ISM conditions, whereas two other cores from the Pakistan margin are mainly under IWM influence. Sea surface temperatures (SST) derived from transfer functions based on census counts of planktic foraminifera were studied in comparison to geochemical proxies, alkenone biomarkers and trace elemental composition in planktic foraminiferal calcite. During the first of the three time slices, the last 250 years, IWM conditions were coupled to large-scale oscillation patterns originating in the Pacific (El Niño- Southern Oscillation, ENSO and Pacific Decadal Oscillation, PDO) and Atlantic (North Atlantic Oscillation, NAO). The coupling, however, was not stable but weakened since the beginning of the 20th century. Phases of very intense IWM conditions were coupled to NAO, suggesting a strong extratropical link to the monsoon climate. Over the second interval, the last 2,000 years, the ’Common Era’ (CE) variations of IWM conditions on centennial-scales were linked climatic warm phases of the North Atlantic region, namely the end of the ’Roman Warm Period’ (at ~450 CE) and the ’Medieval Warm Period’ (~950–1250 CE). The third interval during the early- to mid-Holocene is marked by more intense ISM conditions compared to modern times. The results further suggest, that, instead of water mass changes, bottom-water OMZ conditions were controlled by surface water processes during weak ISM phasesDer Indische Monsun ist ein beeindruckendes Klimaphänomen und ein wichtiger Einflussfaktor für den interhemisphärischen Wärme- und Feuchtetransport. Aufgrund des starken saisonalen Charakters wird der Indische Monsun unterteilt in Indischen Sommermonsun (ISM), welcher von Juli bis September vorkommt, und In- dischen Wintermonsun (IWM), welcher von Januar bis März vorkommt. Der ISM und die mit ihm einhergehenden Niederschläge ist eine wichtige Frischwasserquelle, da er für den größten Teil des jährlichen Niederschlages in Indien und den umliegenden Ländern verantwortlich ist. Die künftige Entwicklung der ISM Variabilität abschätzen zu können ist daher von höchster Wichtigkeit für den wirtschaftlichen Erfolg und die landwirtschaftliche Entwicklung in einer der dichtbesiedelsten Regionen der Erde. Das Verständnis potentieller Veränderungen des ISM aufgrund zukünftiger Klimaveränderungen erfordert die genaue Kennt- nis der Monsungeschichte. Daher ist es entscheidend Archive vergangener ISM Variabilität auf Zeitskalen zu untersuchen, die wichtig für gesellschaftliche Entwicklungen sind, d.h. Jahre bis Dekaden. Darüberhinaus ist unser Verständnis des Monsunsystems ohne eine bessere Kenntnis der IWM Variabilität unvollständig. Aufgrund der extremen Saisonalität des Indischen Monsuns, die durch gegensätzliche Richtungen der vorherrschenden oberflächennahen Winde hervorgerufen wird, hat der Monsun einen starken Einfluss auf die Hydrographie des Arabischen Meeres. Der ISM wird durch intensiven Auftrieb charakterisiert, der von Abkühlung des Oberflächenwassers und erhöhter Wasseroberflächenproduktivität im nordwestlichen Arabischen Meer begleitet ist. Die trockenen und kalten Winde des IWM sind verbunden mit Verdunstungskühlung des Oberflächenwassers und einer konvektiven Vertiefung der durchmischten Schicht, was zu Nährstoffeintrag und erhöhter Wasseroberflächenproduktivität im nordöstlichen Teil des Beckens führt. Hohe Primäproduktion und verminderte Durchlüftung des Zwischen- schichtwassers führt zu starken und stabilen Sauerstoffmangelbedingungen in mittleren Wassertiefen. Die Bedingungen in der Sauerstoffminimumzone (OMZ) begünstigen den Entzug von Stickstoff über die Reduktion von biologisch ver- fügbarem anorganischem Stickstoff zu gasförmigem Distickstoffmonoxid (N2O), einem wichtigen Treibhausgas. Diese Dissertation konzentriert sich auf die ultrahochauflösende Rekonstruktion beider saisonaler Monsunkomponenten während dreier relativ kurzer Zeitscheiben des Holozäns mithilfe eines gemeinschaftlichen Multi-Proxy-Ansatzes. Um die vergangenen Änderungen des Monsunsystems zu untersuchen, wurden drei hemipelagische Sedimentkerne aus der Region des Arabischen Meeres unter- sucht. Ein Kern vom nördlichen Kontinenthang vor Oman wurde unter dem maßgeblichen Einfluss des ISM abgelagert, wohingegen zwei weitere Kerne vor Pakistan hauptsächlich unter dem Einfluss des IWM standen. Basierend auf Zählungen planktischer Foraminiferen wurden mittels Transferfunktionen Meeresoberflächentemperaturen (SST) abgeleitet und im Vergleich zu geochemischen Proxies, Alkenon-Biomarkern und Spurenelementzusammensetzungen im Kalzit planktischer Foraminiferenschalen untersucht. Während der ersten der drei Zeitscheiben, der letzten 250 Jahre, waren IWM Bedingungen anscheinend an großskalige Oszillationsmuster gekoppelt, die ihren Ursprung im Pazifik (El Niño-Southern Oscillation, ENSO und Pazifische Dekadenoszillation, PDO) und Atlantik (Nordatlantische Oszillation, NAO) haben. Die Kopplung war jedoch nicht stabil, sondern nahm seit Beginn des 20. Jahrhunderts ab. Phasen sehr intensiver IWM Bedingungen waren an NAO gekoppelt, was eine starke extratropische Verbindung des Monsunklimas andeutet. Während des zweiten untersuchten Intervals, der letzten 2.000 Jahre, die ’Common Era’ (CE), waren Variationen des IWM auf hundertjährigen Zeitskalen mit Warmphasen der Nordatlantikregion verbunden, nämlich dem Ende der Römischen Warmzeit (um ~450 CE) und der Mittelalterlichen Warmzeit (~950–1250 CE). Das dritte Interval während des frühen bis mittleren Holozäns ist im Gegensatz zu heute durch intensivere ISM Bedingungen geprägt. Die Ergebnisse deuten darüberhinaus darauf hin, dass anstelle von Veränderungen der Zwischenwassermassen, die OMZ Bedingungen durch Prozesse des Oberflächenwassers während schwächerer ISM-Phasen beeinflusst wurden

Impacts of Different Light Spectra on CBD, CBDA and Terpene Concentrations in Relation to the Flower Positions of Different Cannabis Sativa L. Strains

Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country-specific regulations. The plant has gained interest due to its medically important secondary metabolites, cannabinoids and terpenes. Besides biotic and abiotic stress factors, secondary metabolism can be manipulated by changing light quality and intensity. In this study, three morphologically different cannabis strains were grown in a greenhouse experiment under three different light spectra with three real light repetitions. The chosen light sources were as follows: a CHD Agro 400 ceramic metal-halide lamp with a sun-like broad spectrum and an R:FR ratio of 2.8, and two LED lamps, a Solray (SOL) and an AP67, with R:FR ratios of 13.49 and 4, respectively. The results of the study indicated that the considered light spectra significantly influenced CBDA and terpene concentrations in the plants. In addition to the different light spectra, the distributions of secondary metabolites were influenced by flower positions. The distributions varied between strains and indicated interactions between morphology and the chosen light spectra. Thus, the results demonstrate that secondary metabolism can be artificially manipulated by the choice of light spectrum, illuminant and intensity. Furthermore, the data imply that, besides the cannabis strain selected, flower position can have an impact on the medicinal potencies and concentrations of secondary metabolites

Impacts of Different Light Spectra on CBD, CBDA and Terpene Concentrations in Relation to the Flower Positions of Different Cannabis Sativa L. Strains

Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country-specific regulations. The plant has gained interest due to its medically important secondary metabolites, cannabinoids and terpenes. Besides biotic and abiotic stress factors, secondary metabolism can be manipulated by changing light quality and intensity. In this study, three morphologically different cannabis strains were grown in a greenhouse experiment under three different light spectra with three real light repetitions. The chosen light sources were as follows: a CHD Agro 400 ceramic metal-halide lamp with a sun-like broad spectrum and an R:FR ratio of 2.8, and two LED lamps, a Solray (SOL) and an AP67, with R:FR ratios of 13.49 and 4, respectively. The results of the study indicated that the considered light spectra significantly influenced CBDA and terpene concentrations in the plants. In addition to the different light spectra, the distributions of secondary metabolites were influenced by flower positions. The distributions varied between strains and indicated interactions between morphology and the chosen light spectra. Thus, the results demonstrate that secondary metabolism can be artificially manipulated by the choice of light spectrum, illuminant and intensity. Furthermore, the data imply that, besides the cannabis strain selected, flower position can have an impact on the medicinal potencies and concentrations of secondary metabolites

Impact of Three Different Light Spectra on the Yield, Morphology and Growth Trajectory of Three Different Cannabis sativa L. Strains

Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country specific regulations. Plant growth, morphology and metabolism can be manipulated by changing light quality and intensity. Three morphologically different strains were grown under three different light spectra with three real light repetitions. Light dispersion was included into the statistical evaluation. The light spectra considered had an influence on the morphology of the plant, especially the height. Here, the shade avoidance induced by the lower R:FR ratio under the ceramic metal halide lamp (CHD) was of particular interest. The sugar leaves seemed to be of elementary importance in the last growth phase for yield composition. Furthermore, the last four weeks of flowering were crucial to influence the yield composition of Cannabis sativa L. through light spectra. The dry flower yield was significantly higher under both LED treatments compared to the conventional CHD light source. Our results indicate that the plant morphology can be artificially manipulated by the choice of light treatment to create shorter plants with more lateral branches which seem to be beneficial for yield development. Furthermore, the choice of cultivar has to be taken into account when interpreting results of light studies, as Cannabis sativa L. subspecies and thus bred strains highly differ in their phenotypic characteristics

Impact of Three Different Light Spectra on the Yield, Morphology and Growth Trajectory of Three Different Cannabis sativa L. Strains

Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country specific regulations. Plant growth, morphology and metabolism can be manipulated by changing light quality and intensity. Three morphologically different strains were grown under three different light spectra with three real light repetitions. Light dispersion was included into the statistical evaluation. The light spectra considered had an influence on the morphology of the plant, especially the height. Here, the shade avoidance induced by the lower R:FR ratio under the ceramic metal halide lamp (CHD) was of particular interest. The sugar leaves seemed to be of elementary importance in the last growth phase for yield composition. Furthermore, the last four weeks of flowering were crucial to influence the yield composition of Cannabis sativa L. through light spectra. The dry flower yield was significantly higher under both LED treatments compared to the conventional CHD light source. Our results indicate that the plant morphology can be artificially manipulated by the choice of light treatment to create shorter plants with more lateral branches which seem to be beneficial for yield development. Furthermore, the choice of cultivar has to be taken into account when interpreting results of light studies, as Cannabis sativa L. subspecies and thus bred strains highly differ in their phenotypic characteristics

Spatio-temporal variations of climate along possible African-Arabian routes of H. sapiens expansion

Eastern Africa and Arabia were major hominin hotspots and critical crossroads for migrating towards Asia during the late Pleistocene. To decipher the role of spatiotemporal environmental change on human occupation and migration patterns, we remeasured the marine core from Meteor Site KL 15 in the Gulf of Aden and reanalyzed its data together with the aridity index from ICDP Site Chew Bahir in eastern Africa and the wet-dry index from ODP Site 967 in the eastern Mediterranean Sea using linear and nonlinear time series analysis. These analyses show major changes in the spatiotemporal paleoclimate dynamics at 400 and 150 ka BP (thousand years before 1950), presumably driven by changes in the amplitude of the orbital eccentricity. From 400 to 150 ka BP, eastern Africa and Arabia show synchronized wet-dry shifts, which changed drastically at 150 ka BP. After 150 ka BP, an overall trend to dry climate states is observable, and the hydroclimate dynamics between eastern Africa and Arabia are negatively correlated. Those spatio-temporal variations and interrelationships of climate potentially influenced the availability of spatial links for human expansion along those vertices. We observe positively correlated network links during the supposed out-of-Africa migration phases of H. sapiens. Furthermore, our data do not suggest hominin occupation phases during specific time intervals of humid or stable climates but provide evidence of the so far underestimated potential role of climate predictability as an important factor of hominin ecological competitiveness

Konzeption eines Partialmodells zur Berechnung der Risikotragfähigkeit eines Schaden- und Unfallversicherers

Die nachfolgende Arbeit untersucht den Standardansatz zur Berechnung der Kapitalanforderungen eines Schaden- und Unfallversicherers. Mit einem internen stochastischen Risikomodell wird überprüft ob individuelle Risikomodule den GDV -Standardansatz verbessern können und ein angepasstes Partialmodell zur Berechnung der Kapitalanforderungen konzipiert werden kann