@phdthesis{Klock2001, author = {Klock, Heike}, title = {Hydrogeology of the Kalahari in north-eastern Namibia}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-1181287}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2001}, abstract = {This study has focused on hydrogeological and hydrochemical settings of the Northern Namibian Kalahari Catchment which is the Namibian part of the Makgadikgadi-Kalahari-Catchment. Recharge has been the subject of process-understanding, quantification and regionalisation. Within the semiarid study area a bimodal surface constitution is prominent: hardrocks areas allow for fast infiltration along karsts and joints, whereas areas covered by unconsolidated sediments receive minor diffuse recharge and locally some preferred flow path recharge develops along shrinkage cracks and rootlets. Five substratum classes have been soil physically studied: Pans and vleis, brown to red soils, dune sand, soil with an aeolian influence, and calcrete. Aeolian sands are most promising for the development of direct diffuse recharge. Recharge by preferred flow might occur in all soil classes either due to joints in calcrete or structures and rootlets in soils. All soil classes contribute to indirect recharge because even the dune sand allows, albeit very locally, the generation of runoff. The occurrences of recharge through the unconsolidated soil and the hardrocks have been confirmed by hydrograph interpretation and by a study of hydrochemical data which identified groundwater of flood water and flood water after soil passage composition. Other prominent hydrochemical processes in the Kalahari are associated with the carbonate-equilibrium-system, mixing with highly mineralised water that is either sulphate (central area) or chloride dominated (fringe area) and development of sodium hydrogencarbonate water types. The latter is mostly generated by feldspar weathering. Variations of the hydrochemical compositions were observed for shallow groundwaters. They do not only reflect the recharge amount but also the recharge conditions, e.g. a wetter year is allowing more vegetation which increases the hydrogencarbonate content. Inverse determination of recharge by the chloride mass balance method gives recharge amounts between 0.2 and locally more than 100 mm/a. The least favoured recharge conditions are found for Kalahari covered areas, the largest amount occurs in the Otavi area. The distribution of recharge areas within the catchment is rather complex and regionalisation of recharge for the entire catchment was done by a forward approach using satellite images and by an inverse approach using hydrochemical data. From the inverse hydrochemical approach a basin-wide balanced recharge amount of 1.39 mm/a is achieved. The forward approach gave a basin-wide figure of 0.88 (minimum assumption) to 4.53 mm/a (maximum assumption). A simplistic groundwater flow model confirmed the results from the minimum recharge regionalisation by satellite images and the result from the hydrochemical approach. Altogether a mutually verified basin-wide recharge figure of ca. 1 mm/a turns out.}, subject = {Kalahari}, language = {en} } @article{KlemdMatthesSchuessler1994, author = {Klemd, R. and Matthes, S. and Sch{\"u}ssler, Ulrich}, title = {Reaction textures and fluid behaviour in very high-pressure calc-silicate rocks of the M{\"u}nchberg gneiss complex, Bavaria, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31035}, year = {1994}, abstract = {Calc-silicate rocks occur as elliptical bands and boudins intimately interlayered with eclogites and high-pressure gneisses in the Munchberg gneiss complex of NE Bavaria. Core assemblages of the boudins consist of grossular-rich garnet, diopside, quartz, zoisite, clinozoisite, calcite, rutile and titanite. The polygonal granoblastic texture commonly displays mineral relics and reaction textures such as postkinematic grossular-rich garnet coronas. Reactions between these mineral phases have been modelled in the CaO-Al203-Si02-C02-H2 0 system with an internally consistent thermodynamic data base. High-pressure metamorphism in the calc-silicate rocks has been estimated at a minimum pressure of 31 kbar at a temperature of 630°C with X^oSQ.Gi. Small volumes of a C02-N2-rich fluid whose composition was buffered on a local scale were present at peak-metamorphic conditions. The P-T conditions for the onset of the amphibolite facies overprint are about 10 kbar at the same temperature. A'co., of the H20-rich fluid phase is regarded to have been <0.03 during amphibolite facies conditions. These P-T estimates are interpreted as representing different stages of recrystallization during isothermal decompression. The presence of multiple generations of mineral phases and the preservation of very high-pressure relics in single thin sections preclude pervasive post-peak metamorphic fluid flow as a cause of a re-equilibration within the calc-silicates. The preservation of eclogite facies, very high-pressure relics as well as amphibolite facies reactions textures in the presence of a fluid phase is in agreement with fast, tectonically driven unroofing of these rocks.}, language = {en} } @article{KleemannZamoraVillacisChiluisaetal.2022, author = {Kleemann, Janina and Zamora, Camilo and Villacis-Chiluisa, Alexandra Belen and Cuenca, Pablo and Koo, Hongmi and Noh, Jin Kyoung and F{\"u}rst, Christine and Thiel, Michael}, title = {Deforestation in continental Ecuador with a focus on protected areas}, series = {Land}, volume = {11}, journal = {Land}, number = {2}, issn = {2073-445X}, doi = {10.3390/land11020268}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262078}, year = {2022}, abstract = {Forest conservation is of particular concern in tropical regions where a large refuge of biodiversity is still existing. These areas are threatened by deforestation, forest degradation and fragmentation. Especially, pressures of anthropogenic activities adjacent to these areas significantly influence conservation effectiveness. Ecuador was chosen as study area since it is a globally relevant center of forest ecosystems and biodiversity. We identified hotspots of deforestation on the national level of continental Ecuador between 1990 and 2018, analyzed the most significant drivers of deforestation on national and biome level (the Coast, the Andes, The Amazon) as well as inside protected areas in Ecuador by using multiple regression analysis. We separated the national system of protected areas (SNAP) into higher and lower protection levels. Besides SNAP, we also considered Biosphere Reserves (BRs) and Ramsar sites. In addition, we investigated the rates and spatial patterns of deforestation in protected areas and buffer zones (5 km and 10 km outwards the protected area boundaries) using landscape metrics. Between 1990 and 2018, approximately 4\% of the accumulated deforestation occurred within the boundaries of SNAP, and up to 25.5\% in buffer zones. The highest rates of deforestation have been found in the 5 km buffer zone around the protected areas with the highest protection level. Protected areas and their buffer zones with higher protection status were identified as the most deforested areas among SNAP. BRs had the highest deforestation rates among all protected areas but most of these areas just became BRs after the year 2000. The most important driver of deforestation is agriculture. Other relevant drivers differ between the biomes. The results suggest that the SNAP is generally effective to prevent deforestation within their protection boundaries. However, deforestation around protected areas can undermine conservation strategies to sustain biodiversity. Actions to address such dynamics and patterns of deforestation and forest fragmentation, and developing conservation strategies of their landscape context are urgently needed especially in the buffer zones of areas with the highest protection status.}, language = {en} } @phdthesis{Klawitter2006, author = {Klawitter, Ruth}, title = {Theoriegeleitete praxisorientierte Lehrerausbildung im Fach Geographie. Eine wissenschaftliche Untersuchung am Standort Studienhaus Geographie im Schullandheim Bauersberg in der Rh{\"o}n}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-20075}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2006}, abstract = {Diese Studie entwickelt und testet ein Ausbildungskonzept f{\"u}r die Lehrerausbildung im Fach Geographie am Beispiel der Bildungseinrichtung Studienhaus Geographie des Schullandheims Bauersberg bei Bischofsheim a.d. Rh{\"o}n. Die theoretischen {\"U}berlegungen beinhalten einen {\"U}berblick {\"u}ber die bestehenden p{\"a}dagogischen Zielsetzungen, die administrativen Grundlagen, die aufgezeigten Defizite der universit{\"a}ren Lehrerausbildung wie die daraus resultierenden Reformans{\"a}tze und Forderungen an eine qualifizierte Lehrerausbildung. F{\"u}r das fallbeispielhaft entwickelte Konzept einer Lehrerausbildung im Fach Geographie stellen die professionstheoretischen Ans{\"a}tze zu einer kompetenzorientierte Lehrerausbildung die Basis dar, auf der die p{\"a}dagogischen Zielsetzungen einer auf Professionalit{\"a}t ausgerichteten Lehrerausbildung formuliert werden. Schwerpunktm{\"a}ßig basiert das Ausbildungskonzept auf dem bildungstheoretischen Dreieck zur Neustrukturierung der Lehrerbildung von BAYER/CARLE/WILDT, welches die Vernetzungsm{\"o}glichkeiten der die Lehrerausbildung kennzeichnenden Bezugssysteme Wissenschaft (im Sinne von Theorie), Praxis (im Sinne von Berufsfeldbezug) und Person (im Sinne von Professionalit{\"a}t) beschreibt. Grundlage des Ausbildungskonzeptes stellen ebenfalls die administrativen Vorgaben der bayerischen Lehrerausbildung dar. Eine wesentliche Rolle f{\"u}r die Konzeption dieser Form der Ausbildung am Standort Studienhaus Geographie spielen neben den strukturellen Voraussetzungen dieser Einrichtung die ge{\"a}ußerten Defizite der universit{\"a}ren Lehrerausbildung, die jeweils in der Aussage einer zu wenig an der Praxis orientierten Ausbildung gipfeln. Untersuchungen zur Qualit{\"a}t der universit{\"a}ren Geographielehrerausbildung geben Hinweise zu einer intensiveren Vermittlung von Methodenkompetenz bez{\"u}glich des Unterrichtsprinzips Handlungsorientierung und des Einsatz von geographischen Arbeitstechniken wie Experimente, Exkursionen/Arbeiten im Gel{\"a}nde etc.. Unterst{\"u}tzt werden die sich daraus ableitenden Optimierungsvorschl{\"a}ge durch die Realisierung verschiedener Reformans{\"a}tze im Fach Geographie wie f{\"a}cher{\"u}bergreifendes, projektorientiertes, in der Zusammenarbeit mit der Schulpraxis stattfindendes Arbeiten an außerschulischen Lernorten und durch die von den jeweiligen Fachvertretern formulierten Richtlinien zur Optimierung der Lehrerausbildung. Das Ausbildungskonzept basiert auf interdisziplin{\"a}r angelegten Lehrveranstaltungen, die in Kooperation der Geographiedidaktik mit der Physischen Geographie, der Humangeographie, der Geologie, der Mineralogie und der Schulpraxis und zur Erarbeitung unterrichtsrelevanter geographischer Ausbildungsinhalte stattfinden. Kennzeichnend ist die Veranstaltungsstruktur Blockveranstaltung, welche handlungs- und projektorientierte, auf Teamarbeit ausgerichtete Arbeitsformen f{\"o}rdert und die gemeinsame Erarbeitung von Ausbildungsinhalten aus fachdidaktischer und fachwissenschaftlicher Perspektive in der Theorie mit anschließender Anwendung bei Gel{\"a}ndearbeiten. Eine Umsetzung der theoretischen Kenntnisse in fachad{\"a}quates, didaktisch-methodisches Unterrichtsmaterial/-vorhaben wie deren Erprobung mit Sch{\"u}lern schließt sich an. Den Abschluss dieser Ausbildungsform bildet eine gemeinsame Evaluation und Reflexion der gesetzten fachdidaktischen, fachwissenschaftlichen und hochschuldidaktischen Zielsetzungen bez{\"u}glich der Ausbildungsinhalte und -methode. In der qualitativen Studie wurde die Eignung des Standortes Studienhaus Geographie f{\"u}r Lehrveranstaltungen, die gem{\"a}ß dem Konzept der theoriegeleiteten praxisorientierten Lehrerausbildung stattfinden, evaluiert. Lehrende der Geographie/Geologie/Mineralogie, Studierende und Lehrkr{\"a}fte wurden in Leitfadeninterviews befragt. In der quantitativen Studie evaluierten alle teilgenommenen Studierende mittels eines Fragebogens dieses Ausbildungskonzept. Sowohl aus der Perspektive der Lehrenden der Fachwissenschaft als auch aus derjenigen der Geographiedidaktik und der Studierenden stellt diese Einrichtung aufgrund ihrer Lage und r{\"a}umlichen wie materiellen Ausstattung einen geeigneten Ausbildungsort f{\"u}r eine universit{\"a}re Lehrerausbildung, die nach p{\"a}dagogischen, fach- und hochschuldidaktischen Kriterien organisiert ist, dar.}, language = {de} } @phdthesis{Kirschke2008, author = {Kirschke, Stefanie}, title = {Bilanzierung des Methanaustauschs zwischen Biosph{\"a}re und Atmosph{\"a}re in Periglazialr{\"a}umen mit Hilfe von Fernerkundung und Modellen am Beispiel des Lena Deltas}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-29024}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2008}, abstract = {Verbleibende Unsicherheiten im Kohlenstoffhaushalt in {\"O}kosystemen der hohen n{\"o}rdlichen Breiten k{\"o}nnen teilweise auf die Schwierigkeiten bei der Erfassung der r{\"a}umlich und zeitlich hoch variablen Methanemissionsraten von Permafrostb{\"o}den zur{\"u}ckgef{\"u}hrt werden. Methan ist ein global abundantes atmosph{\"a}risches Spurengas, welches signifikant zur Erw{\"a}rmung der Atmosph{\"a}re beitr{\"a}gt. Aufgrund der hohen Sensibilit{\"a}t des arktischen Bodenkohlenstoffreservoirs sowie der großen von Permafrost unterlagerten Landfl{\"a}chen sind arktische Gebiete am kritischsten von einem globalen Klimawandel betroffen. Diese Dissertation adressiert den Bedarf an Modellierungsans{\"a}tzen f{\"u}r die Bestimmung der Quellst{\"a}rke nordsibirischer permafrostbeeinflusster {\"O}kosysteme der nassen polygonalen Tundra mit Hinblick auf die Methanemissionen auf regionalem Maßstab. Die Arbeit pr{\"a}sentiert eine methodische Struktur in welcher zwei prozessbasierte Modelle herangezogen werden, um die komplexen Wechselwirkungen zwischen den Kompartimenten Pedosph{\"a}re, Biosph{\"a}re und Atmosph{\"a}re, welche zu Methanemissionen aus Permafrostb{\"o}den f{\"u}hren, zu erfassen. Es wird ein Upscaling der Gesamtmethanfl{\"u}sse auf ein gr{\"o}ßeres, von Permafrost unterlagertes Untersuchungsgebiet auf Basis eines prozessbasierten Modells durchgef{\"u}hrt. Das prozessbasierte Vegetationsmodell Biosphere Energy Hydrology Transfer Model (BETHY/DLR) wird f{\"u}r die Berechnung der Nettoprim{\"a}rproduktion (NPP) arktischer Tundravegetation herangezogen. Die NPP ist ein Maß f{\"u}r die Substratverf{\"u}gbarkeit der Methanproduktion und daher ein wichtiger Eingangsparameter f{\"u}r das zweite Modell: Das prozessbasierte Methanemissionsmodell wird anschließend verwendet, um die Methanfl{\"u}sse einer gegebenen Bodens{\"a}ule explizit zu berechnen. Dabei werden die Prozesse der Methanogenese, Methanotrophie sowie drei verschiedene Transportmechanismen - molekulare Diffusion, Gasblasenbildung und pflanzengebundener Transport durch vaskul{\"a}re Pflanzen - ber{\"u}cksichtigt. Das Methanemissionsmodell ist f{\"u}r Permafrostbedingungen modifiziert, indem das t{\"a}gliche Auftauen des Permafrostbodens in der kurzen arktischen Vegetationsperiode ber{\"u}cksichtigt wird. Der Modellantrieb besteht aus meteorologischen Datens{\"a}tzen des European Center for Medium-Range Weather Forecasts (ECMWF). Die Eingangsdatens{\"a}tze werden mit Hilfe von in situ Messdaten validiert. Zus{\"a}tzliche Eingangsdaten f{\"u}r beide Modelle werden aus Fernerkundungsdaten abgeleitet, welche mit Feldspektralmessungen validiert werden. Eine modifizierte Landklassifikation auf der Basis von Landsat-7 Enhanced Thematic Mapper Plus (ETM+) Daten wird f{\"u}r die Ableitung von Informationen zu Feuchtgebietsverteilung und Vegetationsbedeckung herangezogen. Zeitserien der Auftautiefe werden zur Beschreibung des Auftauens bzw. R{\"u}ckfrierens des Bodens verwendet. Diese Faktoren sind die Haupteinflussgr{\"o}ßen f{\"u}r die Modellierung von Methanemissionen aus permafrostbeeinflussten Tundra{\"o}kosystemen. Die vorgestellten Modellergebnisse werden mittels Eddy-Kovarianz-Messungen der Methanfl{\"u}sse validiert, welche w{\"a}hrend der Vegetationsperioden der Jahre 2003-2006 im s{\"u}dlichen Teil des Lena Deltas (72°N, 126°E) vom Alfred Wegener Institut f{\"u}r Polar- und Meeresforschung (AWI) durchgef{\"u}hrt wurden. Das Untersuchungsgebiet Lena Delta liegt an der Laptewsee in Nordostsibirien und ist durch {\"O}kosysteme der arktischen nassen polygonalen Tundra sowie kalten kontinuierlichen Permafrost charakterisiert. Zeitlich integrierte Werte der modellierten Methanfl{\"u}sse sowie der in situ Messungen zeigen gute {\"U}bereinstimmungen und weisen auf eine leichte Modelluntersch{\"a}tzung von etwa 10\%.}, subject = {Methanemission}, language = {de} } @article{KhareLatifiRossietal.2019, author = {Khare, Siddhartha and Latifi, Hooman and Rossi, Sergio and Ghosh, Sanjay Kumar}, title = {Fractional cover mapping of invasive plant species by combining very high-resolution stereo and multi-sensor multispectral imageries}, series = {Forests}, volume = {10}, journal = {Forests}, number = {7}, issn = {1999-4907}, doi = {10.3390/f10070540}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-197250}, year = {2019}, abstract = {Invasive plant species are major threats to biodiversity. They can be identified and monitored by means of high spatial resolution remote sensing imagery. This study aimed to test the potential of multiple very high-resolution (VHR) optical multispectral and stereo imageries (VHRSI) at spatial resolutions of 1.5 and 5 m to quantify the presence of the invasive lantana (Lantana camara L.) and predict its distribution at large spatial scale using medium-resolution fractional cover analysis. We created initial training data for fractional cover analysis by classifying smaller extent VHR data (SPOT-6 and RapidEye) along with three dimensional (3D) VHRSI derived digital surface model (DSM) datasets. We modelled the statistical relationship between fractional cover and spectral reflectance for a VHR subset of the study area located in the Himalayan region of India, and finally predicted the fractional cover of lantana based on the spectral reflectance of Landsat-8 imagery of a larger spatial extent. We classified SPOT-6 and RapidEye data and used the outputs as training data to create continuous field layers of Landsat-8 imagery. The area outside the overlapping region was predicted by fractional cover analysis due to the larger extent of Landsat-8 imagery compared with VHR datasets. Results showed clear discrimination of understory lantana from upperstory vegetation with 87.38\% (for SPOT-6), and 85.27\% (for RapidEye) overall accuracy due to the presence of additional VHRSI derived DSM information. Independent validation for lantana fractional cover estimated root-mean-square errors (RMSE) of 11.8\% (for RapidEye) and 7.22\% (for SPOT-6), and R\(^2\) values of 0.85 and 0.92 for RapidEye (5 m) and SPOT-6 (1.5 m), respectively. Results suggested an increase in predictive accuracy of lantana within forest areas along with increase in the spatial resolution for the same Landsat-8 imagery. The variance explained at 1.5 m spatial resolution to predict lantana was 64.37\%, whereas it decreased by up to 37.96\% in the case of 5 m spatial resolution data. This study revealed the high potential of combining small extent VHR and VHRSI- derived 3D optical data with larger extent, freely available satellite data for identification and mapping of invasive species in mountainous forests and remote regions.}, language = {en} } @phdthesis{Kempf2000, author = {Kempf, J{\"u}rgen}, title = {Klimageomorphologische Studien in Zentral-Namibia: Ein Beitrag zur Morpho-, Pedo- und {\"O}kogenese}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-5325}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2000}, abstract = {Es werden die Ergebnisse mehrj{\"a}hriger geomorphologische, pedologischer und {\"o}kologischer Feldaufnahmen in Namibia vorgestellt. Der Schwerpunkt der Betrachtung lag auf einem West-Ost-Transekt im zentralen Drittel des Landes zwischen dem s{\"u}dlichen Wendekreis und der Etosha-Region. Das Transekt beschreibt einen klima-geomorphologischen {\"U}bergang vom namibischen Schelf, {\"u}ber das Litoral, die Namib-Rumpffl{\"a}che, das Randstufenvorland mit dem Escarpment und das Hochland mit dem Windhoek-Okahandja-Becken bis zu den ausgedehnten Kontinentalbecken der Kalahari. Schelf, Randstufenvorland, Becken und Kalahari stellen dabei potentielle Akkumulationslandschaften, dar, Hochland und Namib-Fl{\"a}che die zugeh{\"o}rigen Abtragungslandschaften. Der geomorphologische Formenschatz der Akkumulations- und Abtragungslandschaften wurde ebenso analytisch beschrieben, wie die landschafts{\"o}kologische Grundausstattung, v. a. B{\"o}den und Vegetation. Die jeweils ablaufenden Prozesse und Prozesskombinationen wurden mit klimatischen Daten in einem {\"O}kosystemmodell verkn{\"u}pft. Mit Hilfe dieses Modells wurden geomorphologische Reliktformen verschiedener Zeitalter im landschaftlichen Zusammenhang {\"o}kogenetisch interpretiert und ein historischer Ablauf der Milieugeschichte seit dem Endterti{\"a}r rekonstruiert. Unterst{\"u}tzend wurden Proxydaten, v. a. pal{\"a}o{\"o}kologische und geoarch{\"a}ologische herangezogen.}, subject = {Zentralnamibia}, language = {de} } @phdthesis{Kawohl2022, author = {Kawohl, Alexander}, title = {The Petrology and Geochemistry of Igneous Dykes above the Temagami Anomaly (Ontario, Canada) and their Relationship to the 1.85 Ga Sudbury Impact}, doi = {10.25972/OPUS-27961}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-279617}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2022}, abstract = {The area northeast of Sudbury, Ontario, is known for one of the largest unexplained geophysical anomalies on the Canadian Shield, the 1,200 km2 Temagami Anomaly. The geological cause of this regional magnetic, conductive and gravity feature has previously been modelled to be a mafic-ultramafic body at relatively great depth (2-15 km) of unknown age and origin, which may or may not be related to the meteorite impact-generated Sudbury Igneous Complex in its immediate vicinity. However, with a profound lack of outcrops and drill holes, the geological cause of the anomaly remains elusive, a genetic link to the 1.85 Ga Sudbury impact event purely speculative. In search for any potential surface expression of the deep-seated cause of the Temagami Anomaly, this study provides a first, yet comprehensive petrological and geochemical assessment of exotic igneous dykes recently discovered in outcrops above, and drill cores into, the Temagami Anomaly. Based on cross-cutting field relations, petrographic studies, lithogeochemistry, whole-rock Nd-Sr-Pb isotope systematics, and U-Pb geochronology, it was possible to identify, and distinguish between, at least six different groups of igneous dykes: (i) Calc-alkaline quartz diorite dykes related to the 1.85 Ga Sudbury Igneous Complex (locally termed Offset Dykes); (ii) tholeiitic quartz diabase of the regional 2.22 Ga Nipissing Suite/Senneterre Dyke Swarm; (iii) calc-alkaline quartz diabase of the regional 2.17 Ga Biscotasing Dyke Swarm; (iv) alkaline ultrabasic dykes correlated with the 1.88-1.86 Ga Circum-Superior Large Igneous Province (LIP); and (v) aplitic dykes as well as (vi) a hornblende syenite, the latter two of more ambiguous age and stratigraphic position. The findings presented in this study - the discovery of three new Offset Dykes in particular - offer some unexpected insights into the geology and economic potential of one of the least explored areas of the world-class Sudbury Mining Camp as well as into the nature and distribution of both allochthonous and autochthonous impactites within one of the oldest and largest impact structures known on Earth. Not only do the geometric patterns of dyke (and breccia) distribution reaffirm previous notions of the existence of discrete ring structures in the sense of a ~200-km multi-ring basin, but they provide critical constraints as to the pre-erosional thickness and extent of the impact melt sheet, thus helping to identity new areas for Ni-Cu-PGE exploration. Furthermore, this study provides important insights into the pre-impact stratigraphy and the magmatic evolution of the region in general, which reveals to be much more complex, compositionally divers, and protracted than initially assumed. Of note is the discovery of rocks related to the 2.17 Ga Biscotasing and the 1.88-1.86 Ga Circum-Superior magmatic events, as these were not previously known to occur on the southeast margin of the Superior Craton. Shortly predating the Sudbury impact and being contemporaneous with ore-forming events at Thompson (Manitoba) and Raglan (Cape Smith), these magmatic rocks could provide the missing link between unusual mafic, pre-enriched, crustal target rocks, and the unique metal endowment of the Sudbury Impact Structure. The actual geological cause of the Temagami Anomaly remains open to debate and requires the downward extension of existing bore holes as well as more detailed geophysical investigations. The hypothesis of a genetic relationship between Sudbury impact event and Temagami Anomaly is neither borne out by any evidence nor particularly realistic, even in case of an oblique impact, and should thus be abandoned. It is instead proposed, based on circumstantial evidence, that the anomaly might be explained by an ultramafic complex of the 1.88-1.86 Ga Circum-Superior LIP.}, subject = {Impaktstruktur}, language = {en} } @article{KasparOttHertigKasparetal.2019, author = {Kaspar-Ott, Irena and Hertig, Elke and Kaspar, Severin and Pollinger, Felix and Ring, Christoph and Paeth, Heiko and Jacobeit, Jucundus}, title = {Weights for general circulation models from CMIP3/CMIP5 in a statistical downscaling framework and the impact on future Mediterranean precipitation}, series = {The International Journal of Climatology}, volume = {39}, journal = {The International Journal of Climatology}, doi = {10.1002/joc.6045}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-325628}, pages = {3639-3654}, year = {2019}, abstract = {This study investigates the projected precipitation changes of the 21st century in the Mediterranean area with a model ensemble of all available CMIP3 and CMIP5 data based on four different scenarios. The large spread of simulated precipitation change signals underlines the need of an evaluation of the individual general circulation models in order to give higher weights to better and lower weights to worse performing models. The models' spread comprises part of the internal climate variability, but is also due to the differing skills of the circulation models. The uncertainty resulting from the latter is the aim of our weighting approach. Each weight is based on the skill to simulate key predictor variables in context of large and medium scale atmospheric circulation patterns within a statistical downscaling framework for the Mediterranean precipitation. Therefore, geopotential heights, sea level pressure, atmospheric layer thickness, horizontal wind components and humidity data at several atmospheric levels are considered. The novelty of this metric consists in avoiding the use of the precipitation data by itself for the weighting process, as state-of-the-art models still have major deficits in simulating precipitation. The application of the weights on the downscaled precipitation changes leads to more reliable and precise change signals in some Mediterranean sub-regions and seasons. The model weights differ between sub-regions and seasons, however, a clear sequence from better to worse models for the representation of precipitation in the Mediterranean area becomes apparent.}, language = {en} } @phdthesis{Karama2021, author = {Karama, Alphonse}, title = {East African Seasonal Rainfall prediction using multiple linear regression and regression with ARIMA errors models}, doi = {10.25972/OPUS-25183}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-251831}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {The detrimental impacts of climate variability on water, agriculture, and food resources in East Africa underscore the importance of reliable seasonal climate prediction. To overcome this difficulty RARIMAE method were evolved. Applications RARIMAE in the literature shows that amalgamating different methods can be an efficient and effective way to improve the forecasts of time series under consideration. With these motivations, attempt have been made to develop a multiple linear regression model (MLR) and a RARIMAE models for forecasting seasonal rainfall in east Africa under the following objectives: 1. To develop MLR model for seasonal rainfall prediction in East Africa. 2. To develop a RARIMAE model for seasonal rainfall prediction in East Africa. 3. Comparison of model's efficiency under consideration In order to achieve the above objectives, the monthly precipitation data covering the period from 1949 to 2000 was obtained from Climate Research Unit (CRU). Next to that, the first differenced climate indices were used as predictors. In the first part of this study, the analyses of the rainfall fluctuation in whole Central- East Africa region which span over a longitude of 15 degrees East to 55 degrees East and a latitude of 15 degrees South to 15 degrees North was done by the help of maps. For models' comparison, the R-squared values for the MLR model are subtracted from the R-squared values of RARIMAE model. The results show positive values which indicates that R-squared is improved by RARIMAE model. On the other side, the root mean square errors (RMSE) values of the RARIMAE model are subtracted from the RMSE values of the MLR model and the results show negative value which indicates that RMSE is reduced by RARIMAE model for training and testing datasets. For the second part of this study, the area which is considered covers a longitude of 31.5 degrees East to 41 degrees East and a latitude of 3.5 degrees South to 0.5 degrees South. This region covers Central-East of the Democratic Republic of Congo (DRC), north of Burundi, south of Uganda, Rwanda, north of Tanzania and south of Kenya. Considering a model constructed based on the average rainfall time series in this region, the long rainfall season counts the nine months lead of the first principal component of Indian sea level pressure (SLP_PC19) and the nine months lead of Dipole Mode Index (DMI_LR9) as selected predictors for both statistical and predictive model. On the other side, the short rainfall season counts the three months lead of the first principal component of Indian sea surface temperature (SST_PC13) and the three months lead of Southern Oscillation Index (SOI_SR3) as predictors for predictive model. For short rainfall season statistical model SAOD current time series (SAOD_SR0) was added on the two predictors in predictive model. By applying a MLR model it is shown that the forecast can explain 27.4\% of the total variation and has a RMSE of 74.2mm/season for long rainfall season while for the RARIMAE the forecast explains 53.6\% of the total variation and has a RMSE of 59.4mm/season. By applying a MLR model it is shown that the forecast can explain 22.8\% of the total variation and has a RMSE of 106.1 mm/season for short rainfall season predictive model while for the RARIMAE the forecast explains 55.1\% of the total variation and has a RMSE of 81.1 mm/season. From such comparison, a significant rise in R-squared, a decrease of RMSE values were observed in RARIMAE models for both short rainfall and long rainfall season averaged time series. In terms of reliability, RARIMAE outperformed its MLR counterparts with better efficiency and accuracy. Therefore, whenever the data suffer from autocorrelation, we can go for MLR with ARIMA error, the ARIMA error part is more to correct the autocorrelation thereby improving the variance and productiveness of the model.}, subject = {Regression}, language = {en} }