We develop and use a new version of the Terrestrial Ecosystem Model (TEM) to study how rates of methane (CH4) emissions and consumption in high-latitude soils of the Northern Hemisphere have changed over the past century in response to observed changes in the region’s climate. We estimate that the net emissions of CH4 (emissions minus consumption) from these soils have increased by an average 0.08 Tg CH4 per year during the 20th century. Our estimate of the annual net emission rate at the end of the century for the region is 51 Tg CH4 per year. Russia, Canada, and Alaska are the major CH4 regional sources to the atmosphere; responsible for 64%, 11%, and 7% of these net emissions, respectively. Our simulations indicate that large inter-annual variability in net CH4 emissions occurred over the last century. If CH4 emissions from the soils of the pan-Arctic region respond to future climate changes as our simulations suggest they have responded to observed climate changes over the 20th century, a large increase in high latitude CH4 emissions is likely and could lead to a major positive feedback to the climate system. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/). / This study was supported by a NSF biocomplexity grant (ATM-0120468), the NASA Land Cover and Land Use Change Program (NAG5-6257), and by funding from MIT Joint Program on the Science and Policy of Global Change, which is supported by a consortium of government, industry and foundation sponsors.

There is increasing evidence for high magnitude dust storms in high latitude environments. Yet, Aeolian processes in these areas have been largely understudied and therefore our knowledge of these systems is limited. Understanding dust emission processes from the high latitudes regions is of increasing importance because future climate scenarios indicate a reduction in terrestrial ice masses and an expansion in glacial outwash plains which are the main dust sources in high latitude environments. Of these regions, Iceland is the most researched high latitude dust source region, however our understanding of processes which lead to dust events are still poorly understood. This thesis examines the interlinking relationship between dust source and dust particle sedimentology and the physical and meteorological drivers which promote or inhibit dust emission in Iceland. This is achieved through active aeolian monitoring at source during two monitoring periods at Markarfljot, South Iceland. These measurements are complimented using secondary data sources (e.g. meteorological and satellite data), sedimentological mapping and particle analysis and laboratory abrasion experiments. This thesis is the first high resolution multi event record of dust emissions in the high latitudes and concludes by showing that potential dust concentrations and dust particle size are driven by the interlinking relationship between wind speed, sediment texture and surface moisture. Factors that affect the potential sediment availability for dust events are more important in the high latitudes than in the subtropics in driving spatial and temporal variability in dust emission. Measurements presented in this thesis are required to verify and tune regional and global modelling attempts to quantify the potential contribution of high latitude dust in the Earth system. However, further measurements are required to fully understand seasonal changes in dust emissions, across a variety of dust source units within all high latitude dust source regions.

A dissertação ora apresentada teve como objetivo central identificar e sistematizar as estratégias de transmidiação desenvolvidas no âmbito da produção da obra ficcional Latitudes (2013, 2014), um projeto transmídia veiculado em três plataformas diferentes: YouTube, televisão e cinema e, respectivamente, em três formatos: websérie, série de TV e longa metragem. Trata-se de pesquisa que utiliza a técnica de estudo de caso para analisar o surgimento de obras ficcionais produzidas para distribuição em diversas plataformas O trabalho discute o surgimento de novos gêneros e formatos relacionando-os ao contexto da hipertelevisão (Scolari, 2014) e da distribuição de conteúdos em multiplataformas, que marca a experiência estética audiovisual na contemporaneidade, proporcionando novas formas de produção, consumo e fruição. Também são discutidos modelos de negócio na cultura da convergência (Jenkins, 2008), nomeadamente no YouTube - repositório para a websérie Latitudes -, a partir da distribuição e consumo cada vez mais pautados em plataformas streaming, que ganham espaço frente à grade horária tradicional televisiva, no modelo broadcast. Apoiados nos estudos de linguagem de Bakhtin (2003) e em discussões sobre gêneros feitas por Barthes (2009), Eco (1994) e Mungioli (2012), os resultados das análises sugere uma aproximação entre os gêneros ficcional e documental na versão seriada exibida na televisão. Em termos de estratégias de transmidiação desenvolvidas em Latitudes, a análise revelou que a obra incorpora modelos de distribuição e consumo que se apresentam como tendências atuais na produção audiovisual brasileira. Quanto à construção narrativa, observamos como principais resultados o uso das estratégias de propagação (Fechine, 2013) e de reassistibilidade (Mittel, 2011) para o estabelecimento da transmidiação em Latitudes. Também incorporamos às discussões a análíse de estratégias de product placement, a partir de inserções roteirizadas, como modelo de capitalização eficaz em produtos audiovisuais que contam com a internet como principal veículo de distribuição. / The present study aims to identify and systematize transmediation strategies developed by the producers of the series Latitudes (2013, 2014), a project distributed in three different platforms: internet (YouTube), television and cinema (so, in three formats: webseries, TV series and film). The work discusses the emergence of new genres and formats relating them to the context of hipertelevision (Scolari, 2014) and the multi-platform content distribution, which marks the audiovisual experience in contemporary culture and ensures more autonomy and agency to the audiences (Castells, 2009). We also discuss the new business opportunities in the convergence culture (Jenkins, 2008), particularly on YouTube, which works as a repository for the webseries Latitudes, with the distribution and consumption increasingly guided by streaming platforms, that are gaining ground against the traditional television broadcast model. It was also possible to see that these new dynamics, supported by the Internet, create new production processes. Based on the Language theory of Bakhtin (2003) and reflections on genres using Barthes (2009), Eco (1994) and Mungioli (2012). Through these analyzes, we see a connection between the fictional and documentary genres in the television version of our empirical object. After these advances, we reach the stage of systematization of transmediation strategies developed in Latitudes, realizing that it incorporates different kinds of distribution and consumption that are presented as trends in the Brazilian audiovisual production. As main results, we identified propagation strategies (Fechine, 2013), and the use of rewatchability (Mittel, 2011) for the establishment of transmidiation in Latitudes. We also add to the discussion the strategy of product placement (Miller, 2014), through scripted insertions, as an effectively capitalization model for audiovisual products that rely on the internet as a primary vehicle of distribution.

A dissertação ora apresentada teve como objetivo central identificar e sistematizar as estratégias de transmidiação desenvolvidas no âmbito da produção da obra ficcional Latitudes (2013, 2014), um projeto transmídia veiculado em três plataformas diferentes: YouTube, televisão e cinema e, respectivamente, em três formatos: websérie, série de TV e longa metragem. Trata-se de pesquisa que utiliza a técnica de estudo de caso para analisar o surgimento de obras ficcionais produzidas para distribuição em diversas plataformas O trabalho discute o surgimento de novos gêneros e formatos relacionando-os ao contexto da hipertelevisão (Scolari, 2014) e da distribuição de conteúdos em multiplataformas, que marca a experiência estética audiovisual na contemporaneidade, proporcionando novas formas de produção, consumo e fruição. Também são discutidos modelos de negócio na cultura da convergência (Jenkins, 2008), nomeadamente no YouTube - repositório para a websérie Latitudes -, a partir da distribuição e consumo cada vez mais pautados em plataformas streaming, que ganham espaço frente à grade horária tradicional televisiva, no modelo broadcast. Apoiados nos estudos de linguagem de Bakhtin (2003) e em discussões sobre gêneros feitas por Barthes (2009), Eco (1994) e Mungioli (2012), os resultados das análises sugere uma aproximação entre os gêneros ficcional e documental na versão seriada exibida na televisão. Em termos de estratégias de transmidiação desenvolvidas em Latitudes, a análise revelou que a obra incorpora modelos de distribuição e consumo que se apresentam como tendências atuais na produção audiovisual brasileira. Quanto à construção narrativa, observamos como principais resultados o uso das estratégias de propagação (Fechine, 2013) e de reassistibilidade (Mittel, 2011) para o estabelecimento da transmidiação em Latitudes. Também incorporamos às discussões a análíse de estratégias de product placement, a partir de inserções roteirizadas, como modelo de capitalização eficaz em produtos audiovisuais que contam com a internet como principal veículo de distribuição. / The present study aims to identify and systematize transmediation strategies developed by the producers of the series Latitudes (2013, 2014), a project distributed in three different platforms: internet (YouTube), television and cinema (so, in three formats: webseries, TV series and film). The work discusses the emergence of new genres and formats relating them to the context of hipertelevision (Scolari, 2014) and the multi-platform content distribution, which marks the audiovisual experience in contemporary culture and ensures more autonomy and agency to the audiences (Castells, 2009). We also discuss the new business opportunities in the convergence culture (Jenkins, 2008), particularly on YouTube, which works as a repository for the webseries Latitudes, with the distribution and consumption increasingly guided by streaming platforms, that are gaining ground against the traditional television broadcast model. It was also possible to see that these new dynamics, supported by the Internet, create new production processes. Based on the Language theory of Bakhtin (2003) and reflections on genres using Barthes (2009), Eco (1994) and Mungioli (2012). Through these analyzes, we see a connection between the fictional and documentary genres in the television version of our empirical object. After these advances, we reach the stage of systematization of transmediation strategies developed in Latitudes, realizing that it incorporates different kinds of distribution and consumption that are presented as trends in the Brazilian audiovisual production. As main results, we identified propagation strategies (Fechine, 2013), and the use of rewatchability (Mittel, 2011) for the establishment of transmidiation in Latitudes. We also add to the discussion the strategy of product placement (Miller, 2014), through scripted insertions, as an effectively capitalization model for audiovisual products that rely on the internet as a primary vehicle of distribution.

No description available.

The following report documents the inspiration, themes, preparation, and challenges faced in writing the feature length screenplay Horse Latitudes. This is the story of a young woman who works as a spam writer for an advertising agency. In hopes of moving up in the company, Cairo begins working undercover for her boss, writing erotica blog entries for his personal website. She begins using the people closest to her for material, thus betraying her own morals. As she descends deeper into debt to her boss, she becomes physically ill until she can no longer survive in the world she has created. This is a story based on the author’s own experiences of working for a spam company and being committed to a hospital. This report also includes supplemental planning documents used in the final draft. / text

No description available.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24422号 / 理博第4921号 / 新制||理||1703(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 齊藤 昭則, 教授 石岡 圭一, 教授 田口 聡 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

The plasma drifts or electric fields and their structures in the ionosphere affect the accuracy of the present-day space-based systems. For the first time, we have used ionospheric plasma drift data from Jicamarca radar measurements to study the climatology of altitudinal variations of vertical and zonal plasma drifts in low latitudes during daytime. We used data from 1998 to 2014 to derive these climatological values in bimonthly bins from 150 km to 600 km. For the vertical plasma drifts, we observed the drifts increasing with altitudes in the morning and slowly changing to drifts decreasing with altitude in the afternoon hours. The drifts change mostly linearly from E- to F-region altitudes except in the morning hours of May-June when the gradients are very small. The zonal drifts show a highly nonlinear increase in the westward drifts at the lower altitudes and then increase slowly at the higher altitudes. We see a break in the slopes at lower altitudes during the morning hours of March-April and May-June. The E-region zonal drifts, unlike vertical drifts, show a very large variability compared to F-region drifts. We also explored the altitudinal profiles of vertical drifts during late afternoon and evening hours when the electrodynamic properties in the ionosphere change rapidly. For the first time using drifts up to 2000 km, we have shown the drifts increase and decrease below and above the F-region peak before becoming height independent. These structures arise to satisfy the curl-free condition of electric fields in low latitudes. The altitudinal gradients of vertical drifts are balanced by a time derivative of the zonal drifts to satisfy the curl-free condition of electric fields. We have shown how these structures evolve with local time around the dusk sector and change with solar flux. During solar minimum, the peak region can go well below 200 km. The present-day electric field models do not incorporate these gradients, particularly in the evening sectors when they change very rapidly. Very often their results do not match with the observations. Including these gradients along with proper magnetic field models will improve the model results and accuracy of our navigation, communication, and positioning systems.

Cette étude a pour objectif d'analyser le rôle des ondes de Rossby dans la variabilité des courants-jets troposphériques des moyennes latitudes à l'aide d'un modèle numérique idéalisé. Elle s'intéresse aux mécanismes dynamiques responsables de la persistance des principaux modes de variabilité : celui de déplacement méridien et celui de pulsation d'amplitude. Le premier est souvent le principal mode de variabilité du fait de sa grande persistance causée par une rétroaction positive des ondes de Rossby.Deux nouveaux types de rétroactions négatives ont été mis en évidence à une échelle de temps plus courte que cette rétroaction classique et dont le mécanisme dépend de la nature des ondes impliquées. Ces différents mécanismes sont aussi retrouvés et ainsi validés dans le contexte plus réaliste des données de réanalyse.Une réflexion sur les conséquences du changement climatique est aussi proposée via l'étude de sensibilité menée sur trois paramètres clés du modèle : le gradient méridien de température, conduisant à un mode de déplacement plus persistant dans le futur, la position moyenne du jet, conduisant à un mode moins persistant pour des jets plus proches du pôle, et enfin la friction dans les basses couches de l'atmosphère, aussi étudiée car étant un paramètre plutôt difficile à évaluer et présentant une forte disparité entre les modèles.Cette thèse a donc permis de mettre en évidence deux nouveaux mécanismes de rétroaction des ondes sur les courants-jets et de développer des diagnostics théoriques qui pourront être plus amplement testés et appliqués dans d'autres contextes, particulièrement des réanalyses et des simulations de climat réalistes. / This study investigate the impact of Rossby waves on the tropospheric midlatitude eddy-driven jets using an idealized numerical model. It focuses on the dynamical mechanisms driving the persistence of the main modes of variability: a shifting mode and a pulsing mode. The shifting mode is often found to be the leading mode of variability due to an enhanced persistence caused by a positive feedback of Rossby waves. Two new kinds of negative feedbacks have been found for a shorter time-scale than the more classical feedback which mechanism depends on wave properties. These new mechanisms have also been found in the more realistic set up of reanalysis. The impact of climate change is also investigated using the sensitivity analysis of the model to three key parameters : the meridional gradient of temperature, which leads to longer lasting phases of the shifting mode in the future, the jet mean position, which leads to less persistent shifting mode for poleward shifted jets, and frictional damping, because it is a parameter difficult to tune and which varies between numerical models. In conclusion, two new feedback mechanisms acting on eddy-driven jets variability have been found and theoretical diagnostics have been developed and could be used to probe more realistic data such as future climate simulations and reanalysis.