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Space-Time Evolution of the Intraseasonal Variability in the Indian Summer Monsoon and its Association with Extreme Rainfall Events : Observations and GCM SimulationsKarmakar, Nirupam January 2016 (has links) (PDF)
In this thesis, we investigated modes of intraseasonal variability (ISV) observed in the Indian monsoon rainfall and how these modes modulate rainfall over India. We identified a decreasing trend in the intensity of low-frequency intraseasonal mode with increasing strength in synoptic variability over India. We also made an attempt to understand the reason for these observed trends using numerical simulations.
In the first part of the thesis, satellite rainfall estimates are used to understand the spatiotem-poral structures of convection in the intraseasonal timescale and their intensity during boreal sum-mer over south Asia. Two dominant modes of variability with periodicities of 10–20-days (high-frequency) and 20–60-days (low-frequency) are found, with the latter strongly modulated by sea surface temperature. The 20–60-day mode shows northward propagation from the equatorial In-dian Ocean linked with eastward propagating modes of convective systems over the tropics. The 10–20-day mode shows a complex space-time structure with a northwestward propagating anoma-lous pattern emanating from the Indonesian coast. This pattern is found to be interacting with a structure emerging from higher latitudes propagating southeastwards. This could be related to ver-tical shear of zonal wind over northern India. The two modes exhibit variability in their intensity on the interannual time scale and contribute a significant amount to the daily rainfall variability in a season. The intensities of the 20–60-day and 10–20-day modes show significantly strong inverse and direct relationship, respectively, with the all-India June–September rainfall. This study also establishes that the probability of occurrence of substantial rainfall over central India increases significantly if the two intraseasonal modes simultaneously exhibit positive anomalies over the region. There also exists a phase-locking between the two modes.
In the second part of the thesis, we investigated the changing nature of these intraseasonal modes over Indian region, and their association with extreme rainfall events using ground based observed rainfall. We found that the relative strength of the northward propagating 20–60-day mode has a significant decreasing trend during the past six decades, possibly attributed to the weakening of large-scale circulation in the region during monsoon. This reduction is compensated by a gain in synoptic-scale (3–9 days) variability. The decrease in the low-frequency ISV is associated with a significant decreasing trend in the percentage of extreme events during the active phase of the monsoon. However, this decrease is balanced by a significant increasing trend in the percentage of extreme events in break phase. We also find a significant rise in occurrence of extremes during early- and late-monsoon months, mainly over the eastern coastal regions of India. We do not observe any significant trend in the high-frequency ISV.
In the last part of the thesis, we used numerical simulations to understand the observed changes in the ISV features. Using the atmospheric component of a global climate model (GCM), we have performed two experiments: control experiment (CE) and heating experiment (HE). The CE is the default simulation for 10 years. In HE, we prescribed heating in the atmosphere in such a way that it mimics the conditions for extreme rainfall events as observed over central India during June– September. Heating is prescribed primarily during the break phase of the 20–60-day mode. This basically increases the number of extremes, majority of which are in break phase. The design of the experiment reflects the observed current scenario of increased extreme events during breaks. We found that the increased extreme events in the HE decreased the intensity of the 20–60-day mode over the Indian region. This reduction is associated with a reduction of rainfall in active phase and increase in the length of break phase. A reduction in the seasonal mean over India is also observed. The reduction of active phase rainfall is linked with an increased stability of the atmosphere over central India. Lastly, we propose a possible mechanism for the reduction of rainfall in active phase. We found that there is a significant reduction in the strength of the vertical easterly shear over the northern Indian region during break–active transition phase. This basically weakens the conditions for the growth of Rossby wave instability, thereby elongating break phase and reducing the rainfall intensity in the following active phase.
This study highlights the redistribution of rainfall intensity among periodic (low-frequency) and non-periodic (extreme) modes in a changing climate scenario, which is further tested in a modeling study. The results presented in this thesis will provide a pathway to understand, using observations and numerical model simulations, the ISV and its relative contribution to the Indian summer monsoon. It can also be used for model evaluation.
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Sistemas de cultivos de milho consorciado ou não com plantas de cobertura de solo: Aspectos produtivos, socioeconomicos e de qualidade / Farming systems of corn associated or not with cover crops: Productive aspects, economic and soil qualityChieza, Emerson Dalla 10 February 2010 (has links)
The availability of small areas for cultivation together with the technical and economic deficiencies often aggravated by socio-cultural aspects, creating the small farms, a scenario likely to farming practices with a high degree of unsustainability. From this contest was held this field study, between September 2008 and October 2009 an agrarian reform settlement aimed at examining different forms of soil management, its potential for improving soil quality and its implications for socioeconomic in small farms. The experimental design was randomized blocks with split plots with four replications. The treatments consisted of plots of crop systems: maize + cowpea (M + FC), maize + Pigeon pea dwarf (M + GA); corn + velvet bean (M + MP) and maize monocrop (MS). The sub-plots by the forms of fertilizer: organic source - turkey litter (AO); Without the addition of nutrients (SA) and mineral source - NPK (AM). We assessed aspects related to grain yield of corn, physical and chemical properties of soil in two layers (0-5 and 5-10 cm depth) and socioeconomic aspects of managements. Water stress led to a negative effect of M + FC on grain yield of maize, which in turn was not affected by M + MP, and were higher in treatments with AM (P <0.05). Cultures GA and MP had the highest intakes of nitrogen (N) via aboveground. The cropping systems showed positive results for bulk density and soil porosity. There was a tendency to decrease in aggregate stability for all systems studied, including the fallow treatment. There was no increase (P <0.05) of soil organic carbon (COT) of the systems studied, only attenuated the decrease of this natural element. Showed an increase (P> 0.05) compared to the initial content of N in the soil, and the consortium M + MP which showed the highest levels in both studied layers. The study also found decreased (P <0.05) in the attributes SMP pH, base saturation, exchangeable potassium content, reflecting the increase (P <0.05) in aluminum saturation. Another aspect observed was the increase (P <0.05) CTCpH7.em both layers. The systems studied showed net negative reflections of the high cost of some inputs and low yields obtained. The demand for labor by the managements of the systems has been affected by sowing cover crops for soil, and the management of these, either by restricting the growth of vegetation or the harvest of the seeds. Although it was short time for consistent evaluations, the results obtained by cropping systems indicate that there are gains in productive aspects, contribution of COT and N, especially in soil physical properties. This condition reflects the possibility of replacing the "conventional" system of cultivation of maize by the systems studied, with gains in sustainability, in many ways. / A disponibilidade de pequenas áreas para cultivo aliada as deficiências técnicas e econômicas, agravadas muitas vezes por aspectos sócio-culturais, cria nas pequenas propriedades, um cenário propenso a práticas agropecuárias com elevado grau de insustentabilidade. A partir deste contesto, foi realizado este estudo de campo, no período de setembro de 2008 e outubro de 2009, num assentamento de reforma agrária objetivando investigar diferentes formas de manejo de solo, seu potencial de melhoria na qualidade do solo e suas implicações sócio-econômicas em pequenas propriedades rurais. O delineamento experimental utilizado foi blocos ao acaso com parcelas subdivididas, com quatro repetições. Os tratamentos foram compostos nas parcelas pelos sistemas de cultivo: Milho + Feijão caupi (M + FC); Milho + Guandu anão (M + GA); Milho + Mucuna preta (M + MP) e Milho em cultivo solteiro (MS). Nas sub-parcelas pelas formas de adubação: Fonte orgânica cama de peru (AO); Sem adição de nutrientes (SA) e Fonte mineral NPK (AM). Foram avaliados aspectos relacionados ao rendimento de grãos da cultura do milho, atributos físicos e químicos do solo, em duas camadas (0-5 e 5-10 cm de profundidade) e aspectos socioeconômicos dos manejos. O estresse hídrico conduziu a um efeito negativo do M+ FC no rendimento de grãos de milho, que por sua vez não foi afetado por M + MP, e foram superiores nos tratamentos com AM (P<0,05). As culturas GA e MP apresentaram os maiores aportes de nitrogênio (N) via fitomassa aérea. Os sistemas de cultivos apresentaram resultados positivos em relação à densidade volumétrica do solo e porosidade. Observou-se a tendência a diminuição da estabilidade dos agregados para todos os sistemas estudados, inclusive no tratamento em pousio. Não houve incremento (P<0,05) de Carbono orgânico no solo (COT) dos sistemas estudados, apenas atenuaram a diminuição natural deste elemento. Observou-se incremento (P>0,05) em relação aos teores iniciais de N no solo, sendo o consórcio M + MP o que apresentou os maiores teores em ambas camadas estudadas. Também foi constatado diminuição (P<0,05) nos atributos pH SMP, saturação por bases, teor de potássio trocável, com reflexos no acréscimo (P<0,05) da saturação por alumínio. Outro aspecto observado foi o aumento (P<0,05) da CTCpH7.em ambas camadas. Os sistemas estudados apresentaram receita líquida negativa, reflexos do alto custo de alguns insumos e baixas produtividades obtidas. A demanda de mão de obra por parte dos manejos dos sistemas foi impactada pela semeadura das plantas de cobertura de solo, e pelo manejo dessas, seja pela contenção do crescimento vegetativo ou pela colheita das sementes. Embora tenha sido curto espaço de tempo para avaliações consistentes, os resultados obtidos pelos sistemas de cultivo indicam haver ganhos, em aspectos produtivos, aporte de COT e N, sobretudo, em atributos físicos do solo. Esta condição reflete na possibilidade de substituir o sistema convencional de cultivo do milho pelos sistemas estudados, com ganhos em sustentabilidade, sob vários aspectos.
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Adaptation au changement climatique sur les alpages. Modéliser le système alpage-exploitations pour renouveler les cadres d'analyse de la gestion des alpages par les sytèmes pastoraux / Adaptation to climate change on alpine pastures. Modelling the alpine pasture - farms systems to renew the analytical framework of alpine pastures management by pastoral farming systemsNettier, Baptiste 23 June 2016 (has links)
Les alpages sont des espaces utilisés par la majorité des exploitations d’élevage de montagne et de Provence, qui y envoient tout ou partie de leurs troupeaux durant la saison estivale. Ce sont des milieux très riches sur le plan environnemental, mais aussi très fragiles et gérés exclusivement par le pâturage des troupeaux, constituant de ce fait des espaces particuliers dans la problématique de l’adaptation au changement climatique pour les systèmes d’élevage provençaux et de montagne. Or le constat est fait que les approches de diagnostic d’alpage et les références utilisées au plan pastoral présentent des lacunes pour appréhender la gestion dynamique des alpages : vision statique des végétations d’alpage et des pratiques, prise en compte des aléas et de la variabilité interannuelle souvent réduite à un coefficient forfaitaire de sécurité... et pas de prise en considération des interactions entre alpage et exploitations utilisatrices. Afin de renouveler ces cadres d’analyse, notre travail de thèse propose une modélisation conceptuelle du fonctionnement du système « alpage-exploitations », intégrant les plans biophysique et de la gestion. La construction du modèle s’appuie sur la combinaison de travaux en écologie et en agronomie « système », et de dires d’expert (modélisation participative). Le modèle est mis à l’épreuve sur une diversité de cas, issus du réseau Alpages Sentinelles dans le massif Alpin. Une analyse de la vulnérabilité des systèmes à la recrudescence des aléas climatiques est effectuée en étudiant leur exposition aux aléas puis leur sensibilité ; afin d’intégrer la dynamique de long terme du changement climatique dans la gestion des alpages, une analyse mobilisant les théories de la résilience socio-écologique est proposée en complément. / Alpine pastures, or mountain summer pastures can be defined as permanent grasslands used in summer by mountain and surrounding plains farmers (especially Provence in the French Alps). They are rich but fragile ecosystems, managed exclusively through the grazing of herds. Therefore adaptation to climate change is very specific on these spaces. Pastoral diagnosis methods and technical references are insufficient to analyse dynamic management of summer mountain pastures: static vision of vegetation and practices, climatic hazards considered only through a security coefficient, and no consideration for interactions between summer pastures and farms. In order to renew these analytical frameworks, our PhD thesis proposes a conceptual model of how the system “mountain summer pastures-farm” works, both in biophysical terms and in terms of management. The building of this model relies both on researches in ecology and agronomy, and on participatory modelling. We evaluate the model through an analysis of the vulnerability to climatic hazards of a diversified sample of systems. In order to take into account long term dynamics of climate change, we also mobilise the theories of social-ecological resilience.
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Ferdinand Schlögel-Merzin a jeho fond / Ferdinand Schlögel-Merzin and His FondsSudzinová, Tereza January 2017 (has links)
This thesis deals with Ferdinand Schlögel-Merzin's (1899-1983) early works related to the 1913 Scout summer camp led by Josef Hendrych. It was set up at the Bohemian Paradise near the site of Kumburk castle ruins. In addition to the analysis of Schlögel-Merzin's diary and memoirs, the thesis also aims to provide information on the origination of Czech Scouting with respect to Schlögel-Merzin and his influence. The thesis also contains the inventory of Schlögel-Merzin's personal fonds, stored in the Literary archive of the Museum of Czech Literature. The collection includes material from the entire Schlögel-Merzin's creative period, mainly unpublished manuscripts - poems, poetry collections, prose, plays or travelogue lectures - and archive documents connected to his writing or travels to foreign countries in the 1920s and 1930s.
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Role of Aerosols in Modulating the Intraseasonal Oscillations of Indian Summer MonsoonBhattacharya, Anwesa January 2016 (has links) (PDF)
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.
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Kúpny rozhodovací proces spotrebiteľa na trhu letných dovoleniek / Purchase decision-making process of consumers in the market of summer vacationSoroková, Lenka January 2011 (has links)
The aim of this thesis is to analyse the consumer's purchase decision-making process at the market of the summer vacations and capture current trends of buying summer vacation in the Czech market. The first two chapters are devoted to basic definitions and approaches, serving to understanding consumer behaviour, description of the marketing mix of tourism and the factors affecting the buying decision of the individual. Next part of the thesis examines different phases of the purchase decision-making process by using secondary data. The fourth chapter briefly describes the tourism market in the Czech Republic, its entities and services overview of tourism. The final part is devoted to the analysis of a questionnaire survey carried out by me and the acquired results. My own research is supported by data from Market -- Media -- Lifestyle (MML). The end of the work is composed of the result summary and conclusion of the investigation and it shows clear process of buying summer vacation on the basis of available data.
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Analyse de contaminants d’intérêt émergent dans l’Estuaire et le Golfe du Saint-Laurent par chromatographie liquide couplée à la spectrométrie de masse haute résolutionPicard, Jean-Christophe 12 1900 (has links)
Les contaminants d’intérêt émergent (CIEs) ont fait l’objet d’un nombre croissant d’études ces dernières années, notamment dans les milieux aquatiques. Il existe cependant certains manques de connaissances concernant leur occurrence et leur distribution dans les systèmes hydrologiques complexes, notamment la distribution verticale à travers différentes masses d’eau. Les variations saisonnières entre conditions estivales et hivernales restent difficiles à établir en raison des conditions météorologiques hivernales rigoureuses au Canada, limitant l’accessibilité des échantillons. Ainsi, ce projet de maîtrise a porté sur l’étude de 90 CIEs, comprenant des pesticides, des produits pharmaceutiques et marqueurs anthropiques, des hormones et des substances perfluorées dans un environnement océanographique, soit l’Estuaire et le Golfe du Saint-Laurent (EGSL). Deux expéditions ont été menées en conditions hivernales (hivers 2019 et 2020) et une en conditions estivales (été 2019). Ces missions ont permis d’évaluer, dans un premier temps, la distribution spatiale des CIEs dans l’eau de surface le long de l’EGSL, puis, dans un second temps, la variation des concentrations de surface associées aux différentes températures, salinités, couvertures de glace, processus de dégradation ou débit du fleuve des saisons. Par ailleurs, un échantillonnage à plusieurs profondeurs durant l’hiver 2020 a permis de dresser un profil vertical des concentrations le long de l’Estuaire et du Golfe du Saint-Laurent. Finalement, la filtration de larges volumes d’eau de surface durant l’hiver 2020 a permis d’évaluer la concentration des CIEs adsorbés sur la matière en suspension (phase particulaire) et conséquemment, le partitionnement entre la phase dissoute et particulaire, influencé par la variation de la salinité et de la quantité de matière en suspension. Les analyses ont été effectuées grâce au développement et à la validation d’une nouvelle méthode multi-résidus impliquant la chromatographie liquide à ultra-haute performance (UHPLC) couplée à la spectrométrie de masse à haute résolution (HRMS). À notre connaissance, il s’agit de la première étude à caractériser divers contaminants émergents dans les eaux de l’Estuaire et du Golfe du Saint-Laurent, particulièrement pendant la période hivernale et à travers la colonne d’eau. / Contaminants of Emerging Concern (CECs) have been increasingly studied since recent years, for instance in aquatic ecosystems. However, there exist significant knowledge gaps regarding their occurrence and distribution in complex hydrological systems, including their vertical distribution in different water bodies. Seasonal variations between summer and winter conditions are also difficult to establish because of the rigorous winter weather conditions in Canada, restricting the accessibility of samples. Thus, this project focused on the study of 90 CECs, including pesticides, pharmaceuticals and anthropogenic markers, hormones, and perfluorinated substances in an oceanographic environment, namely the St. Lawrence Estuary and Gulf (SLEG). Two expeditions were conducted under winter conditions (winters 2019 and 2020) and one under summer conditions (summer 2019). These expeditions first assessed the spatial distribution of CECs along the SLEG and, secondly, the seasonal and annual variations of the concentrations associated with the different temperatures, salinities, ice cover, degradation processes or seasonal river flow. In addition, sampling at multiple depths during the winter of 2020 allowed for documenting the vertical profiles of CECs throughout the SLEG. Finally, the filtration of large volumes of surface water during the winter of 2020 allowed for the evaluation of the CECs adsorbed onto suspended particle matter (SPM) and consequently, the partitioning between dissolved and particulate phases, influenced by salinity and SPM variations. Analyses were performed following the development and validation of a new multi-residue method involving ultra-high performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS). To the best of our knowledge, this is the first study to report the occurrence of emerging contaminants in the SLEG, especially during the winter season and across the water column.
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Liniová stavba v rámci životního cyklu z pohledu BIM / Line construction within the life cycle from the perspective of BIMVacková, Veronika January 2017 (has links)
The aim of the work was the usage of the Building Information Modelling system to ensure the complete building-up, including the working part of the line constructions. In the first part of my thesis I was dealing with the costs of the total life of the line construction, the line construction life-cycle, with the difference between the Building Information Modelling model and traditional projecting, with the participators participants of the Building Information Modelling model and which levels in the Building Information Modelling exist. In the practical part I was dealing with two levels of the Building Information Modelling designing, in which I set the total price of the building researched and then I was comparing them. In the final chapter of the thesis working expenses were set which are involved in the expenses of the total life.
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Signatures détritiques des changements paléoenvironnementaux du Quaternaire récent dans le bassin nord de la mer de Chine du Sud / Detrital signatures of Late Quaternary paleoenvironmental changes in the northern South China SeaChen, Quan 08 December 2016 (has links)
Le but de cette thèse est de reconstruire l’évolution environnementale de la région nord de la mer de Chine du Sud au cours du Quaternaire récent. L'objectif est d'identifier des traceurs des interactions continent-océan, de la mousson est-asiatique et de la circulation océanique. Pour cela, des analyses des minéralogies argileuse et magnétique, de la composition en éléments majeurs, et la taille des grains ont été effectuées sur les sédiments de carotte MD12-3432 couvrant les derniers 400 ka avec un taux de sédimentation variant entre 4.5 et 24 cm/ka. Nous avons tout d'abord amélioré les calibrations de la composition en éléments majeurs obtenue par XRF core-scanning. En effet, celles-ci ne corrigeaient pas des variations de teneur en eau interstitielle observées la séquence sédimentaire étudiée. Nous avons donc proposé une correction polynomiale quadratique qui convertit maintenant correctement les données XRF core-scanning en concentrations précises d’éléments majeurs. La composition en élément majeurs, les minéralogies argileuse et magnétique, et la granulométrie indiquent que les changements climatiques à basse latitude influencent les diverses fractions terrigènes de différentes manières. Considérant d’abord les éléments majeurs et les argiles, nous observons que les rapports smectite/(illite+chlorite) et K₂O/Al₂O₃ présentent tous deux des cyclicités orbitales. Le rapport K₂O/Al₂O₃ qui reflète la contribution relative des apports de Taiwan par dénudation, augmente pendant les interglaciaires quand la mousson d’été asiatique est forte. Le rapport smectite/(illite+chlorite) présente des cyclicités également liées à l’excentricité et à la précession en phase avec les changements d’insolation de l’hémisphère nord en été. Connaissant les régions sources de ces argiles, nous suggérons que l’apport en smectite est étroitement lié à l'intensité de l’altération chimique et à la dénudation fluvial induite par les fortes précipitations de mousson, tandis que l’apport d’illite/chlorite depuis Taiwan répond principalement à la dénudation. Le rapport smectite/(illite+chlorite) reflète ainsi principalement l'intensité de l’altération chimique contemporaine (rapide) et donc l’intensité de la mousson d'été asiatique. Les résultats obtenus confirment que la mousson d'été asiatique est renforcée pendant les périodes interglaciaires et quand l'insolation d'été boréal est forte. Les propriétés magnétiques sédimentaires offrent des informations complémentaires sur les changements environnementaux passés dans cette région. La fraction magnétique de la carotte MD12-3432 est composée de magnétites, sulfures de fer et hématite. Des augmentations de teneur en hématite et des diminutions de la granulométrie sédimentaire sont observées aux minima de précession. Ces évènements qui ont lieu pendant les périodes arides pourraient illustrer des apports éoliens depuis le nord de la Chine, liés à des changements d'intensité et/ou de route des vents, probablement aussi liés à l’intensification de la mousson d'hiver. Outre les changements climatiques de basse latitude, le climat global et l'activité tectonique influencent aussi les apports terrigènes dans cette région. Les augmentations à long terme de la teneur en pyrrhotite par rapport à la magnétite et à l’hématite, de la teneur de illite/chlorite indiquent une contribution croissante de sédiment fine d'origine Taiwanaise au cours des derniers 400 ka. Ceci est très probablement lié à l’intensification de l'orogenèse taïwanais. A l'échelle glaciaire-interglaciaire, les variations synchrones des compositions argileuse et magnétique, de la taille des grains sédimentaires et magnétiques, et des taux de sédimentation sont attribuées aux changements de niveau marin. En effet, les bas niveaux marins pendant les périodes glaciaires exposent l’immense plateau continental et permettent à la Rivière des Perles de livrer au site du sédiment terrigène en plus grande quantité et plus grossier. / The aim of this study is to reconstruct late Quaternary environmental changes in the northern South China Sea by applying multi-disciplinary proxies of land-sea interaction, East Asian monsoon, and oceanic circulation. Investigations of clay and magnetic mineralogy, major element composition, and grain size were performed on marine sediment Core MD12-3432 retrieved from the continental slope of the northern South China Sea. The core covers the last 400 ka with a sedimentation rate varying between 4.5 and 24 cm/ka. We examined the accuracy of existing calibration methods on major element composition obtained by XRF core-scanning, because downcore variations in interstitial water content should strongly affect scanned element contents. We proposed a quadratic polynomial correction to account for this effect and implemented it in the calibration methods. Data from Core MD12-3432 show that the improved calibration process now correctly converts XRF core-scanning data into major element concentrations. Our results on high-resolution major element composition, clay and magnetic mineralogy, and grain size data indicate that low-latitude climate changes influence various terrigenous fractions in different ways. In bulk sediment, K₂O/Al₂O₃ ratio mainly reflects the relative contribution of detrital supply from Taiwan, and its variation exhibits eccentricity cycles. The ratio increases during interglacials, showing that strong precipitation and denudation are induced by enhanced East Asian summer monsoon. In clay fractions, smectite/(illite+chlorite) ratio presents both eccentricity and precession periodicities, in phase with the northern hemisphere summer insolation changes and therefore with the East Asian summer monsoon evolution. Based on the knowledge of sediment provenances, these results suggest that high smectite/(illite+chlorite) ratios illustrate contemporaneous chemical weathering intensity in Luzon. It supports the understanding that East Asian summer monsoon is enhanced during interglacial periods and when the boreal summer insolation is strong. Therefore, these two ratios are appropriate sedimentary tracers for East Asian summer monsoon evolution in the South China Sea. The magnetic fraction yields complementary information about environmental changes in the South China Sea. The magnetic mineral assemblage of Core MD12-3432 is mainly composed of magnetite, sulphide, and hematite, and the relative contributions of all these magnetic mineral contents change with time. Variations on precessional band related to the low latitude East Asian monsoon are observed in magnetic properties and grain size values. High magnetic inputs with high hematite proportion, which is part of fine-grain sediment, are observed during the precession minima. These events occurring during arid periods may illustrate enhanced eolian inputs caused by changes in intensity and/or winds pathway of winds, probably related to enhanced winter monsoon. Besides the low-latitude climate changes, global climate and tectonic activity also influence the terrigenous composition at the studied site at different timescales. A long-term increase in pyrrhotite content with respect to magnetite and hematite and in illite/chlorite contents indicates an increasing contribution of fine grained sediments from Taiwan. This is most likely related to the intensification of Taiwanese orogeny over the last 400 ka. On glacial-interglacial scale, coeval increases observed in sedimentation rate, magnetite/pyrrhotite content, kaolinite content, and grain size during glacial periods are attributed to sea-level changes. Low sea-level during glacial periods exposes the vast shelf and allows the Pearl River to deliver more and coarser terrigenous sediments to our site.
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Understanding Adaptation and Mitigation Strategies of Andean People: International Network on Climate Change: Project Results & Proceedings of Summer-School 2012Lindner, André January 2013 (has links)
This publication summarizes the main results of the INCAProject during 2011/2012 and the contributions to the according INCA-Summer-School, which took place from September 19th – September 27th 2012 at the Technische Universität Dresden, Faculty of Environmental Sciences, Institute of International Forestry and Forest Products, Professorship of Tropical Forestry in Tharandt, Germany.:AN INTERNATIONAL NETWORK ON CLIMATE CHANGE IMPACTS ON SMALL FARMERS IN THE TROPICAL ANDES – GLOBAL CONVENTIONS FROM A LOCAL PERSPECTIVE S. 1
1. Introduction S. 2
2. The concept of an International Network on Climate Change S. 5
3. The outlook on an endogenous approach S. 9
4. References S. 12
ADAPTATION MEASURES S. 17
Adaptation strategies of Andean campesinos to cope with the climatic variability – Examples from the Mantaro Valley, Peru S. 18
A socio-economic analysis of livelihood strategies in rural forest depending communities in lowland Bolivia under a changing climate S. 20
Who knows what and why? Intra-cultural knowledge variation of agroforestry plants S. 21
Traditional ecological knowledge, resilience and food security: local strategies in three communities in the Yungas ecosystem, La Paz, Bolivia S. 22
Influence of agroforestry systems in risk reduction and climate change adaptation in the Peruvian Andes S. 24
Assessing adaptation to climate change: Environmental and socio-economic changes in the Andes of Bolivia S. 26
Adaptive capacity of rural communities to climate change in the bio-cultural system of the Andes, Bolivia S. 28
Socio-economic analysis of farm-forestry systems: Case studies from Achamayo and Palcazu watersheds, Peruvian Andes S. 29
MONITORING AND MODELING LAND USE CHANGE S.33
Modeling and forecast of changes in land-use and land-cover caused by climate change in the Peruvian Andes S. 34
Land-use and land-cover change in Cotapata National Park – Natural integrated management area, Bolivia S. 37
Monitoring and analyzing land-use / land-cover changes using remote sensing and GIS in the Achamayo and Shullcas region, Peruvian Andes S. 39
Climate change and land-use in the Bolivian Andes S. 41
Modeling the adaptation strategies of farmers of the Andes against climate change and the related development of land-use / land-cover S. 43
MANAGEMENT OF A CHANGING LANDSCAPE S. 45
Evaluating the strategies for the management of biophysical resources in farm communities of the Mantaro Valley, Central Andes of Peru S. 46
Participative planning, monitoring and evaluation system in bio-cultural local communities S. 50
The monitoring program in Apolobamba protected area S. 51
Progress in the diagnosis of biodiversity vulnerability to climate change in Bolivia S. 52
Sectoral program of adaptation to climate change of biodiversity and ecosystems S. 53
DEFORESTATION AND CLIMATE CHANGE S. 55
Possible interactions between climate projections and deforestation scenarios in Bolivia S. 56
Transport and possible climate impacts of aerosols from biomass burning from the Amazon to the Bolivian Andes S. 56
Transboundary air pollution in southern Amazon of Peru S. 57
SUMMARY S. 59
Challenges presented by climate change in the Andean region: Land-use cover change and adaptive response of small farmers S. 60
List of participants and additional information S. 62
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