Surface gravity waves alter the turbulence of the bottom atmosphere and the upper ocean. Accordingly, they can affect momentum flux, heat fluxes, gas exchange and atmospheric mixing. However, in most state-of-the-art Earth System Models (ESMs), surface wave influences are not fully considered or even included. Here, applying surface wave influences into ESMs is investigated from different aspects. Tuning parameterisations for including instantaneous wave influences has difficulties to capture wave influences. Increasing the horizontal resolution of models intensifies storm simulations for both atmosphere-wave coupled (considering the influence of instantaneous wave-induced stress) and stand-alone atmospheric models. However, coupled models are more sensitive to the horizontal resolution than stand-alone atmospheric models. Under high winds, wave states have a big impact on the sea spray generation. Introducing a wave-state-dependent sea spray generation function and Charnock coefficient into a wind stress parameterisation improves the model performance concerning wind speed (intensifies storms). Adding sea spray impact on heat fluxes improves the simulation results of air temperature. Adding sea spray impact both on the wind stress and heat fluxes results in better model performance on wind speed and air temperature while compared to adding only one wave influence. Swell impact on atmospheric turbulence closure schemes should be taken into account through three terms: the atmospheric mixing length scale, the swell-induced momentum flux at the surface, and the profile of swell-induced momentum flux. Introducing the swell impact on the three terms into turbulence closure schemes shows a better performance than introducing only one of the influences. Considering all surface wave impacts on the upper-ocean turbulence (wave breaking, Stokes drift interaction with the Coriolis force, Langmuir circulation, and stirring by non-breaking waves), rather than just one effect, significantly improves model performance. The non-breaking-wave-induced mixing and Langmuir circulation are the most important terms when considering the impact of waves on upper-ocean mixing. Accurate climate simulations from ESMs are very important references for social and biological systems to adapt the climate change. Comparing simulation results with measurements shows that adding surface wave influences improves model performance. Thus, an accurate description of all important wave impact processes should be correctly represented in ESMs, which are important tools to describe climate and weather. Reducing the uncertainties of simulation results from ESMs through introducing surface gravity wave influences is necessary.

abstract: Earth-system models describe the interacting components of the climate system and technological systems that affect society, such as communication infrastructures. Data assimilation addresses the challenge of state specification by incorporating system observations into the model estimates. In this research, a particular data assimilation technique called the Local Ensemble Transform Kalman Filter (LETKF) is applied to the ionosphere, which is a domain of practical interest due to its effects on infrastructures that depend on satellite communication and remote sensing. This dissertation consists of three main studies that propose strategies to improve space- weather specification during ionospheric extreme events, but are generally applicable to Earth-system models: Topic I applies the LETKF to estimate ion density with an idealized model of the ionosphere, given noisy synthetic observations of varying sparsity. Results show that the LETKF yields accurate estimates of the ion density field and unobserved components of neutral winds even when the observation density is spatially sparse (2% of grid points) and there is large levels (40%) of Gaussian observation noise. Topic II proposes a targeted observing strategy for data assimilation, which uses the influence matrix diagnostic to target errors in chosen state variables. This strategy is applied in observing system experiments, in which synthetic electron density observations are assimilated with the LETKF into the Thermosphere-Ionosphere- Electrodynamics Global Circulation Model (TIEGCM) during a geomagnetic storm. Results show that assimilating targeted electron density observations yields on average about 60%–80% reduction in electron density error within a 600 km radius of the observed location, compared to 15% reduction obtained with randomly placed vertical profiles. Topic III proposes a methodology to account for systematic model bias arising ifrom errors in parametrized solar and magnetospheric inputs. This strategy is ap- plied with the TIEGCM during a geomagnetic storm, and is used to estimate the spatiotemporal variations of bias in electron density predictions during the transitionary phases of the geomagnetic storm. Results show that this strategy reduces error in 1-hour predictions of electron density by about 35% and 30% in polar regions during the main and relaxation phases of the geomagnetic storm, respectively. / Dissertation/Thesis / Doctoral Dissertation Applied Mathematics 2018

<div>Over the past twenty years, ridesharing opportunities for smallsats, i.e., secondary payloads, has increased with the introduction of Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) rings. However, the orbits available for these secondary payloads is limited to Low Earth Orbits (LEO) or Geostationary Orbits (GEO). By incorporating a propulsion system, propulsive ESPA rings offer the capability to transport a secondary payload, or a collection of payloads, to regions beyond GEO. In this investigation, the ridesharing scenario includes a secondary payload in a dropped-off Geosynchronous Transfer Orbit (GTO) and the region of interest is the vicinity near the Sun-Earth Lagrange points. However, mission design for secondary payloads faces certain challenges. A significant mission constraint for a secondary payload is the drop-off orbit orientation, as it is dependent on the primary mission. To address this mission constraint, strategies leveraging dynamical structures within the Circular Restricted Three-Body Problem (CRTBP) are implemented to construct efficient and flexible transfers from GTO to orbits near Sun-Earth Lagrange points. First, single-maneuver ballistic transfers are constructed from a range of GTO departure orientations. The ballistic transfer utilize trajectories within the stable manifold structure associated with periodic and quasi-periodic orbits near the Sun-Earth L1 and L2 points. Numerical differential corrections and continuation methods are leveraged to create families of ballistic transfers. A collection of direct ballistic transfers are generated that correspond to a region of GTO departure locations. Additional communications constraints, based on the Solar Exclusion Zone and the Earth’s penumbra shadow region, are included in the catalog of ballistic transfers. An integral-type path condition is derived and included throughout the differential corrections process to maintain transfers outside the required communications restrictions. The ballistic transfers computed in the CRTBP are easily transitioned to the higher-fidelity ephemeris model and validated, i.e., their geometries persist in the ephemeris model. To construct transfers to specific orbits near Sun-Earth L1 or L2, families of two-maneuver transfers are generated over a range of GTO departure locations. The two-maneuver transfers consist of a maneuver at the GTO departure location and a Deep Space Maneuver (DSM) along the trajectory. Families of two-maneuver transfers are created via a multiple- shooting differential corrections method and a continuation process. The generated families of transfers aid in the rapid generation of initial guesses for optimized transfer solutions over a range of GTO departure locations. Optimized multiple-maneuver transfers into halo and Lissajous orbits near Sun-Earth L1 and L2 are included in this analysis in both the CRTBP model and the higher-fidelity ephemeris model. Furthermore, the two-maneuver transfer strategy employed in this analysis are easily extended to other Three-Body systems. </div>

The Earth's climate system is driven by varying insolation from the Sun. The dominant variations in insolation are at 23 and 40 thousand year periods, yet for the past million years the Earth's climate has glacial cycles at approximately 100 kyr periodicity. These cycles are a coupled variation in temperature, ice volume, and atmospheric CO₂. Somehow the Earth system's collective response to 23 and 40 kyr insolation forcing produces 100 kyr glacial-interglacial cycles. Generally it has been assumed that the causative mechanisms are a combination of ice dynamics (high ice reflectivity controlling temperature) and ocean circulation (changing carbon partitioning between the deep ocean and the atmosphere, and heat transport to the poles). However, these proposed mechanisms have not yet resulted in a compelling theory for all three variations, particularly CO₂. This thesis explores the role of volcanic CO₂ emissions in glacial cycles. I calculate that glacial-driven sea level change alters the pressure on mid-ocean ridges (MORs), changing their CO₂ emissions by approximately 10%. This occurs because pressure affects the thermodynamics of melt generation. The delay between sea level change and the consequent change in MOR CO₂ emissions is several tens-of-thousands-of-years, conceptually consistent with a coupled non-linear oscillation that could disrupt glacial cycles from a 40 kyr mode to a multiple of that period. I develop an Earth system model to investigate this possibility, running for approximately one million years and explicitly calculating global temperatures, ice sheet configuration, and CO₂ concentration in the atmosphere. The model is driven by insolation, with all other components varying in response (and according to their own interactions). This model calculates that volcanism is capable of causing a transition to ̃100 kyr glacial cycles, however the required average volcanic CO₂ emissions are barely within the 95% confidence interval. Therefore it is possible for volcanic systems and glacial cycles to form a 100 kyr coupled oscillation.

Symphony of the spheres in change? Learning in environment for sustainable development in primary school with a scientific and longitudinal approach. This research deals with learning in science, including learning in environment for sustainable development. Learning in environment and sustainable development are obligatory perspectives in science as well as in other school subjects. The longitudinal study started in 2003, concerning 28 pupils nine years of age in a city in southern Sweden. Data collection has been caught in the pupils’ science lessons from year 2003 to 2006. In order to analyse the pupils’ development of concepts in science and in environment for sustainable development, I have videotaped a lot of sequences from the science lessons and followed up with questionnaires and questions in interviews. Stimulated recall is used to find the teacher’s intentions and reactions on the outcome of the lessons. The results are analysed according to the Earth System Science (ESS) model. It is a model, which describes the relations and interactions between the natural spheres: the atmosphere, hydrosphere, lithosphere as well as the biosphere, including man, and the technosphere/anthroposphere. The longitudinal approach resulted in important findings regarding the changes in the pupils’ answers over time. They develop complicated 'concept webs'. The concepts found among the pupils in this study are e.g. the hydrological cycle; life; soil; water in every day life; pollution; non-polluting busses as well as waste; collecting batteries; corrosion; greenhouse and the increasing greenhouse effect. Some concepts e.g. the hydrological cycle, life and soil can from the beginning be classified as concepts used in science, but also to describe what happens in the environment. Concepts as pollution; non-polluting busses; collecting batteries; corrosion; greenhouse and increasing greenhouse effect are used by the pupils to express relations and interactions in and between the natural spheres including man. The relation between man and nature is for the pupils an area of conflicts through the entire study when the pupils from a scientific approach will be aware of the impact on living ecosystems including themselves, today and in the future. The concepts are often connected to each other in a more or less complicated network, 'concepts webs'. The obtained results indicate that the Socratic dialogue is a possible and successful method to use for the development of pupils’ concepts in environmental questions and issues. Another finding in the study is how different methods, e.g. Play and learning, support environmental learning and learning for sustainable development during the science lessons. Play is important in integrated learning and gives opportunity to understand others’ perspectives, Theory of mind. The results indicate an integrated learning process by the pupils, implying in what way they express human impact on nature.

This research deals with learning in science, including learning in environment for sustainable development. Learning in environment and sustainable development are obligatory perspectives in science as well as in other school subjects. The longitudinal study started in 2003, concerning 28 pupils nine years of age in a city in southern Sweden. Data collection has been caught in the pupils’ science lessons from year 2003 to 2006. In order to analyse the pupils’ development of concepts in science and in environment for sustainable development, I have videotaped a lot of sequences from the science lessons and followed up with questionnaires and questions in interviews. Stimulated recall is used to find the teacher’s intentions and reactions on the outcome of the lessons. The results are analysed according to the Earth System Science (ESS) model. It is a model, which describes the relations and interactions between the natural spheres: the atmosphere, hydrosphere, lithosphere as well as the biosphere, including man, and the technosphere/anthroposphere. The longitudinal approach resulted in important findings regarding the changes in the pupils’ answers over time. They develop complicated 'concept webs'. The concepts found among the pupils in this study are e.g. the hydrological cycle; life; soil; water in every day life; pollution; non-polluting busses as well as waste; collecting batteries; corrosion; greenhouse and the increasing greenhouse effect. Some concepts e.g. the hydrological cycle, life and soil can from the beginning be classified as concepts used in science, but also to describe what happens in the environment. Concepts as pollution; non-polluting busses; collecting batteries; corrosion; greenhouse and increasing greenhouse effect are used by the pupils to express relations and interactions in and between the natural spheres including man. The relation between man and nature is for the pupils an area of conflicts through the entire study when the pupils from a scientific approach will be aware of the impact on living ecosystems including themselves, today and in the future. The concepts are often connected to each other in a more or less complicated network, 'concepts webs'. The obtained results indicate that the Socratic dialogue is a possible and successful method to use for the development of pupils’ concepts in environmental questions and issues. Another finding in the study is how different methods, e.g. Play and learning, support environmental learning and learning for sustainable development during the science lessons. Play is important in integrated learning and gives opportunity to understand others’ perspectives, Theory of mind. The results indicate an integrated learning process by the pupils, implying in what way they express human impact on nature.

[pt] O objetivo da dissertação é analisar criticamente o uso do conceito do Antropoceno pela linha crítica de teoria das Relações Internacionais. Isso se faz com um foco específico na origem do conceito em Ciência do Sistema Terrestre (CST), e através de uma discussão geral sobre autoridade científica atribuída à ciência moderna e suas conexões com práticas de world-making, entendidas especificamente como cosmologias científicas, e em relação com mobilização de propostas na política internacional. Nesse sentido, a discussão explora a construção de CST e propõe a formulação do Antropoceno como relacionada com os comprometimentos políticos dessa disciplina – a partir daí, sugere-se o uso da problematização Foucaultiana como forma de análise das soluções políticas ao Antropoceno propostas pela disciplina. A seguir, a dissertação conecta as Ciências do Sistema Terrestre com outros momentos de desenvolvimento da ciência moderna com o âmbito de mover uma discussão geral sobre o poder de uma autoridade científica legitimar formas de política internacional através de práticas de world-making. Com isso, a discussão expande em dois mundos e formulações de política internacional possíveis advindos de distintas interpretações do Antropoceno. Finalmente, no que se refere à literatura de Relações Internacionais, a dissertação avalia como a apropriação do conceito de Antropoceno a partir de CST é realizada, prestando atenção especificamente na chamada por uma mudança na ontologia da disciplina e na relação entendida como desejável entre teoria e prática política presente na literatura, ambos elementos associados à CST. Por último, a noção de problematização é retomada para se analisar as soluções políticas e intelectuais propostas pela literatura Crítica de Relações Internacionais em sua mobilização do Antropoceno. / [en] This dissertation attempts to critically analyze the mobilization of the concept of the Anthropocene by Critical International Relations literature. It does so with a particular focus on the origins of the concept within Earth System Sciences (ESS), and within a more general discussion over the scientific authority of modern science and its connections to practices of world-making - discussed specifically in terms of scientific cosmologies - and propositions over international politics. As such, the discussion explores the construction of ESS and the formulation of the Anthropocene as related to the political commitments of the discipline and proposes the use of the Foucauldian problematization to analyze the political solutions stemming from the discipline. Then, the dissertation connects Earth System Sciences to other scientific endeavors, in a different historical context in order to move a more generalized discussion on the power of scientific authority to inform international politics through world-making practices. With that, the discussion lays out two possible worlds and political implications stemming from interpretations of the Anthropocene. Finally, within IR literature the dissertation assesses how the appropriation of the Anthropocene is conducted, paying particular attention to the call for an ontological shift within the discipline and to the specific relationship between theory and political action present in the literature, both elements connected to ESS. At last, the notion of problematization is brought back in order to analyze the intellectual and political solutions brought forth by Critical IR in their mobilization of the Anthropocene.

Tropische Regenwälder sind durch anthropogene Aktivitäten gefährdet und wurden als Kippelement identifiziert. Ein Kippen in einen neuen Zustand könnte tiefgreifende Auswirkungen auf das globale Klima haben, sobald die Vegetation von einem bewaldeten in einen Savannen- oder Graslandzustand übergegangen ist. Waldbrände können die Grenze zwischen Savanne und Wald verschieben und somit das dynamische Gleichgewicht zwischen diesen beiden möglichen Vegetationszuständen unter sich änderndem Klima beeinträchtigen. In der vorliegenden Doktorarbeit wurde ein neues Erdsystemmodell entwickelt und angewendet, um explizit die Auswirkungen von Feuer, Klimawandel und Landnutzung auf eine potenzielle tropische Hysterese abzuschätzen. In den ersten beiden Teilen der Arbeit wurde das Vegetationsmodell LPJmL vor allem in Hinblick auf Feuersimulation verbessert und anschließend biophysikalisch an das Erdystemmodell CM2Mc gekoppelt. Im dritten Teil dieser Arbeit wurde das resultierende Modell CM2Mc-LPJmL schließlich angewendet, um wichtige biophysikalische Feuer-Vegetations-Klima-Rückkopplungen und einen potentiellen Kipppunkt bzw. eine Hysterese der tropischen Wälder zu untersuchen. Die Ergebnisse der Experimente zeigten, dass eine alleinige Klima Störung nicht zu einem großflächigen Kipppunkt tropischer Wälder führt. Andererseits führte die vollständige Entwaldung bei einer erhöhten CO2-Konzentration von über 450 ppm und die Wirkung von Waldbränden zu einer Verschiebung großer Teile des Amazonas Regenwaldes in einen stabilen Graslandzustand. Die Leistung dieser Arbeit ist die Entwicklung eines neuen Erdsystemmodells, das die Vorteile des umfassenden dynamischen Vegetationsmodells LPJmL und eines prozessbasierten Feuermodells mit dem geringen Rechenaufwand von CM2Mc verbindet. Diese Doktorarbeit untersuchte zum ersten Mal den expliziten Einfluss von Feuer auf tropische Kipppunkte und auf eine mögliche vegetative Erholung in einem umfassenden feuerfähigen Erdsystemmodell. / Tropical rain forests are endangered by anthropogenic activities and are recognized as one of the terrestrial tipping elements. An ecosystem regime change to a new state could have profound impacts on the global climate, once the biome has transitioned from a forest into a savanna or grassland state. Fire could potentially shift the savanna-forest boundary and hence impact the dynamical equilibrium between these two possible vegetation states under a changing climate. In this thesis, a new Earth system model was developed and applied to explicitly estimate the impact of fire, climate change and land-use on a potential tropical tipping point and hysteresis. The first part of this thesis describes the improvement of simulating fire within the dynamic global vegetation model (DGVM) LPJmL (Lund-Potsdam-Jena-managed-Land). In the second part, the improved LPJmL model was biophysically coupled to the Earth system model CM2Mc, which involved numerous changes in the original LPJmL model. In the third part of this thesis, the resulting model CM2Mc-LPJmL was finally applied to investigate important biophysical fire-vegetation-climate feedbacks and a potential tipping point and hysteresis of tropical forests. The results of the modeling experiments indicated that a sole climate disturbance does not lead to a large-scale tipping of tropical forests into a savanna or grassland state. On the other hand, complete deforestation alongside elevated CO2 above 450 ppm and the impact of fire led to a shift of large parts of the Amazon into a stable grassland state. The contribution of this thesis is the development of a new Earth system model, including the advantages of the comprehensive dynamic vegetation model LPJmL, a process-based fire model and the low computation cost of CM2Mc. This thesis studied for the first time the explicit impact of fire on tropical tipping points and a possible vegetation recovery in a comprehensive fire-enabled Earth system model.

No description available.

Do changes in how cross-equatorial energy transport is partitioned between the ocean and atmosphere impact the hemispheric climate response to forcing? To find out, we alter the cross-equatorial ocean heat transport in a state-of-the-art GCM and ascertain how changes in energy transport and its partitioning impact hemispheric climate and precipitation sensitivity following abrupt CO2-doubling. We further evaluate the applicability our results in CMIP6-class ESMs, where AMOC facilitates the northward cross-equatorial ocean heat transport. In our experiments, changes in ocean cross-equatorial energy transport trigger compensating changes in atmospheric energy transport through changes in the Hadley cells and a shift in the Intertropical Convergence Zone. However, the climate sensitivity in each hemisphere is linearly related to the ocean heat transport convergence, not atmospheric energy transport convergence, due to the impact of ocean heating on evaporation and atmospheric specific humidity. Similarly, we also find that ocean heat transport convergence controls the hemispheric precipitation sensitivity through the impact of ocean heating on surface evaporation. This relationship is also evident in CMIP6 models, where we find differences in hemispheric precipitation sensitivity to be related to the Atlantic Meridional Overturning Circulation (AMOC). Changes in the AMOC control hemispheric differences in upper ocean heat content, which then affect how the hydrologic cycle responds to CO2 forcing in each hemisphere. These results suggest that ocean dynamics impact the hemispheric climate response to CO2 forcing, particularly how much regional precipitation changes with warming. / Graduate