This thesis presents new observations of noctilucent clouds (NLCs), and their environment made with collocated Rayleigh and resonance lidars at Poker Flat Research Range (PFRR), Chatanika, Alaska (65°N, 147° W). In 2019, the Rayleigh Density Temperature Lidar (RDTL) at PFRR was extended to a three-channel system and employed for NLC measurements. RDTL yields measurements with signals a factor of 3-4 times higher than previous studies allowing measurements at higher resolution and to higher altitudes. This study is based on 14 observations in late July and early August between August 8, 2019, and August 11, 2022. NLCs were detected in 10 of the 14 observations, or 70% of the time. The lidar density profiles derived above and below the clouds are used to interpolate the density profiles through the clouds and provide a more accurate estimate of the cloud properties. The clouds are characterized in terms of brightness, duration, and altitude. The NLC peaks are found to be between 80.5 and 84.8 km with backscatter ratios between 7 and 216, and backscatter coefficients between 1.2x10⁻¹⁰ m⁻¹sr⁻¹ and 5.7x10⁻⁹ m⁻¹sr⁻¹. The cloud characteristics are compared with previous lidar observations at PFRR, and their occurrence is compared with observations from the CIPS instrument on the AIM satellite. The continuous lidar density profiles are used to determine the temperatures through the cloud layers, with an initial measurement of temperature above the NLCs at 90 km. Using the collocated Sodium Resonance Wind Temperature Lidar (SRWTL) at PFRR, cloud temperatures are found to be between 141 K and 161 K at 82 km. The temperatures are analyzed in terms of signal quality and other model and satellite sources of temperature. The temperature measurements are discussed in terms of the 'Thermostat Mechanism' where NLCs actively regulate their thermal environment to produce an 'equithermal submesopause'.

This dissertation presents an investigation of aspects of the dynamics of Earth's thermosphere that do not harmonize with the current understanding. Three distinct thermospheric phenomena that correspond to different spatial and temporal scales were examined using Fabry-Perot interferometer measurements of wind and temperature to investigate aspects of thermospheric dynamics. Earth's thermosphere has very high kinematic viscosity and is highly convectively stable. Theory and physics-based models suggest that structures in the horizontal wind on small spatial scales (∼500 km or less) are unlikely to occur in the upper thermosphere. By contrast, a large-scale, persistent, strong wind flow that transports air parcels from the dayside of the polar cap to the nightside, known as cross-polar jet, was found to stall abruptly upon exiting the polar cap above Alaska. Stalling was observed most frequently around mid-winter during periods of low solar activity. The stalling of the crosspolar jet is considerably more abrupt than the first principle models would predict. This phenomenon was investigated as an example of dynamics occurring at intermediate spatial and temporal scales. Along with this meso-scale phenomena, oscillatory perturbations in observed winds and temperatures were examined to test whether these could be the signatures of gravity wave activity. These waves represent a local to synoptic scale behavior. Wave periods ranging from ∼30 min to ∼3 hr were observed. Our data show that gravity wave activity was a nearly ubiquitous feature of winds observed at ∼240 km altitude at auroral latitudes. The actual wave field appears to be complicated, presumably resembling ocean surface waves if they could be visualized. Oscillation amplitudes were typically found to increase with increasing geomagnetic activity and the wave response to geomagnetic activity was similar in both hemispheres. Periods and horizontal wavelengths of the observed oscillations fall within the previously reported range for thermospheric gravity waves. In addition, we examined the thermospheric neutral temperature data to see whether there is any temporal trend in measured temperatures on a time scale of decades. Studies suggest that the Earth's troposphere is warming globally because of anthropogenic emission of greenhouse gases. First principle models suggest that, unlike in the troposphere, greenhouse gases are expected to cool the thermosphere. Consistent with model expectations our data also show a thermospheric cooling trend and the rate of cooling is -27.4 ± 6.2 K/decade. The estimated rate of cooling is more than four times the corresponding uncertainty, indicating that the cooling is statistically significant. However, the observed cooling rate is up to an order of magnitude higher than suggested by simulation studies considering only the effect of CO₂. Nevertheless, the observed trend agrees well with observations of ionospheric temperature at these altitudes using incoherent scatter radar. This long-term temperature trend is an indicator of behavior at the largest spatial and temporal scales. Overall, these three studies together suggest significant shortcomings in our current paradigm for understanding the behavior of the thermosphere. Specifically, stalling of the cross-polar jet shows that spatial structures can arise on much more localized scales than currently appreciated. The ubiquitousness of gravity waves suggests that their role in thermospheric dynamics is probably much more significant than currently appreciated. The effect of anthropogenic changes in atmospheric chemistry appear to be much more substantial than expected. The lowest altitudes at which spacecraft can orbit for an operational useful length of time occur in the Earth's thermosphere. Conditions in the thermosphere impact spacecraft orbits. It is thus necessary to account for the thermospheric dynamics in order to predict the orbit with lowest possible uncertainty and for collision avoidance.

Magnetospheres are poorly understood, largely due to lack of significant amounts of in-situ data and the complexity of the systems. Accurate numerical magnetohydrodynamic (MHD) magnetosphere simulation codes can bolster this lack of observational data. In this thesis, we explore applying mutual information theory techniques to a global-scale Jovian-like magnetosphere simulation provided by the Grid Agnostic MHD for Extended Research Applications (GAMERA) code. The mutual information between two variables is a measure of their dependency and is even capable of detecting nonlinear relationships, unlike traditional linear correlation calculations. Time shifted mutual information is a useful metric for identifying possible causal relationships and improving understanding of overall dynamics within the magnetosphere system. Data from the Juno spacecraft exhibits a 2-3 hour periodicity. Corotating density arm structures seen in the GAMERA simulation, if present at Jupiter, could contribute to this periodicity. We investigate how these density structures modulate the internal dynamics of the magnetosphere. Preliminary analysis indicates that the dynamics of the simulation are largely driven by the advection of the corotating density arm structures. A consistent 3-5 hour periodicity is noticeable and likely caused or contributed to by these density structures. Relationships at 10-20 hours are on the subcorotation timescale and are consistently more nonlinear than relationships found at shorter periodicities.

Understanding the stability of food webs is crucial for resource sustainability and conservation of ecosystems, especially in the context of climate change. Specific models describe the biomass flow in food webs by a set of ordinary differential equations that require the explicit reconstruction of a mathematical expression for each of the interactions or processes, like predator-prey interactions, primary production, and mortality. Although specific models are rich with time-evolution information, limited access for empirical observation of these typically immense systems induce uncertainty in the data and approximations in the corresponding models that can threaten robustness or relevance of results. Generalized models can produce the stability of all the equilibria of specific models that have the same vague structure and bypasses the requirement to specify every function by evoking a normalizing transformation. The analysis is subsequently computationally efficient and can be used to study large food webs with a great number of replicates. Often generalized ecological network studies confine the scope to a small subset of the variable dynamical scenarios, but this limits the interpretations that can be inferred. With this in mind, we develop a deterministic food-web generator that can be used to compare large food webs that differ by only a single link and maintain an expansive dynamical scope. We found behavior that indicates the existence of critical links and a grander theory on topological equivalence. We explicitly show how we can create hypothetical paths the system may traverse upon enrichment of lower trophic levels using the expanded dynamical scope. Generalized modeling is unable to produce evolution solutions among other things, but it has an unlimiting access to the stability of equilibria while specific models provide only a subset of stability data. Generalized modeling is a relatively new method and its relation to specific model outcomes/results is not clearly understood. Specific models can inform generalized modeling studies on properties like coexistence of fixed points or actually occurring relative weighting of flows between ecosystem members. We combined the methods and demonstrated the validity of the abstract technique of generalized modeling in emphasis to its usefulness/power for the analysis of network stability. The specific model provided a unifying explanation to a conglomerate of related microcosm experiments that showed conflicting results on enrichment and implied stabilization upon the hampering of predatory efficiency. We identified the conditions by which enrichment is stabilizing to a steady state when basal species are in a resource-deprived environment but destabilizing if resources become more abundant. A prevalent issue in ecology involves discrepancies between simulation and empirical observation about food-web stability such as how intuition says enrichment or complexity in some way are favorable to stability but mathematical models find it predominately the opposite. A common rationalization for these discrepancies includes discourse on reductionistic versus holistic rhetoric. The idea being that as models become better representations of ecosystems that capture more intricacies and detail, they will help to resolve the issue. We constructed over a million food webs that reveal positive effects on fixed-point stability from the incorporation of more realistic ecosystem features that include species specialization, habitat modularity, and predator's prey preferences. Arctic warming is a portent to changes in species composition and ecological theory predicts the existence of key ecosystem members that have extraordinary influence on overall ecosystem function or the state of the system. Motivated by sea-ice loss and northward expansion of species distributions, ice-obligate species are removed from the food webs and southern competitors are introduced. Although it is common understanding that apex predators can enhance biodiversity, we find the presence of "super killers" significantly destabilizes food webs. Ecosystems have immense complexity with thousands of species, but ecosystem models condense and consider only a few species that are of the most interest or abundance, neglecting the many weak interactions comprising the larger ecosystem. Considering this, we suppose a food web is subsumed by a larger phantom ecological network that represents hypothetically rare species or predator-prey relationships. Each link from the phantom network contributes a variably weak perturbation, but collectively, induce a net positive effect on the average stability of the food webs, considerably so near the optimal perturbation strength.

Interactions between bow shock-reflected (foreshock) ions with solar wind particles can lead to the formation of foreshock transients, frequently observed upstream of the bow shock. Foreshock transients, such as foreshock bubbles, hot flow anomalies, and spontaneous hot flow anomalies, display heated, tenuous cores with large flow deflections bounded by compressional boundaries or shocks. They aid in particle acceleration at the bow shock and their significant dynamic pressure depletions can disturb the magnetosphere-ionosphere system. Thus, studying foreshock transients will expand our understanding of shocks and of the solar wind-planetary magnetosphere coupling throughout the universe. The dissertation presents an observational statistical study and numerical simulations of foreshock transients to investigate their solar wind conditions, properties, and formation mechanisms. The statistical study shows that occurrences of foreshock transients are higher for lower magnetic field strengths and higher solar wind speeds and Alfvén Mach numbers. A geometrical approach with a model bow shock reveals that they typically span up to 3 Earth radii along and extend up to 6 Earth radii from the bow shock. The study also finds that foreshock transients with local density enhancements (substructures), in otherwise density-depleted cores, are often larger in size than those without substructures, and provide variances to the dynamic pressure profiles that could further deform the bow shock surface and lead to more complicated geoeffects. In addition, foreshock transients with and without substructures occur in the same solar wind conditions, thereby implying that substructures are an inherent property of foreshock transients during their evolution. In numerical simulations where injected foreshock ions perform partial gyrations around a discontinuity to generate Hall currents that change the magnetic field topology, foreshock bubbles form from thin discontinuities, and hot flow anomalies form from thick discontinuities. The simulations prove that the foreshock ion current configuration, controlled by the magnetic field change the foreshock ions experience within their gyromotions, determines the magnetic field profile of the structure. Furthermore, the parameter scan results show that the initial foreshock ion distribution types determine how easily foreshock ions can cross the discontinuity and thus how strong the structure forms; parameters that increase their densities or speeds perpendicular to the magnetic field across the discontinuity leads to stronger Hall currents and more significant magnetic field variations. We also find that the initial foreshock ion densities, thermal speeds, and beam speeds all positively and linearly correlate with the expansion speeds and the density compression ratios of the formed structures. This, thereby, provides a possibility to quantify the role of these parameters in the formation and expansion model of foreshock transients and to forecast their aforementioned particle acceleration and geoeffects.

With climate change effects on the rise, the global energy infrastructure requires revision. We first provide a brief review of common energy resources as well as their safety and climate effects. We then compare and contrast nuclear fission and fusion based energy schemes. Difficulties based on the requirements of the fusion triple product, as well as the fast neutrons from the deuterium and tritium reaction are also discussed. The lack of sufficient experimental controls in enhanced confinement modes like the I-mode and the H-mode, lead to difficulties satisfying the restrictions imposed by the Greenwald density limit. These combined with several operational needs like ash and impurity removal, enhanced density control, the ability to access other confinement modes at reduced energy thresholds, motivates the search for a barrier capable of variable energy and density confinement. Self consistent models suggest that unique phase relationships exist between different turbulent instabilities and plasma profiles like temperature and density, that determine the turbulent transport of the quantity. Two common instabilities, driven by the electron and ion temperature gradient, and their unique phase relations are used to arrive at a net phase relation for temperature and for density. Then, using electron and ion radio frequency heating, the difference in phase of the turbulent transport may be locally changed, altering transport dynamics. Methods to increase core temperature while simultaneously increasing density transport, thereby avoiding the Greenwald limit, are discussed. The proposed transport controls are based upon characteristics of the localized radio frequency heating including amplitude, location, and duration. These parameters determine the power deposited in the plasma, and therefore the local ratios of the electron and ion temperature driven instabilities. Aspects of each parameter's effect on radial transport are summarized, with the strongest phase barrier allowing for a ∼ 15% increase of core ion temperature and ∼ 30% decrease of core density.

"The object of this work is to determine the diffusion coefficient (D) of trimethylaluminum (TMA) in the lower thermosphere as a function of altitude (h). This is done by measuring the dispersion of chemiluminescent TMA that is released in discrete quantities, or puffs, from sounding rockets at altitudes 120 to 180 km. Diffusing TMA, which glows in contact with atmospheric oxygen, is observed with stereoscopic ground-based imaging. Brightness profiles across a puff are found to be Gaussian in shape, with width parameter [sigma](t, h) that increases with age (t) of the puff leading to D = [sigma]² (t, h)/2t, independent of time, which is in good agreement with some past results. For example D = (2.5 ± 0.2) x 10³m²s⁻¹ at an altitude of 128 km for the state of the thermosphere at that time. A constant A links three altitude-dependent terms, the diffusion coefficient, temperature and density, at a particular location of the atmosphere, via D(h) = ATS (h)/n(h). It is determined from this study to be A=(4.42±0.05)x10¹⁸(m·s)⁻¹ for s = 0.75. Using these values for A and s, and temperatures and the densities determined from the MSIS-90 thermospheric model, diffusion coefficients for TMA can be determined at other locations and under different geomagnetic conditions"--Leaf iii

This work aims to gain a better understanding of the relationship between glacier motion and water distributed through subglacial drainage systems. A numerical scheme (GlaDS) is used to model both inefficient and efficient drainage systems to see which dominates after the draining of a supraglacial lake on a synthetic glacier that is made up of an outline that features a main branch and a tributary. The geometry is based on the surgetype Black Rapids Glacier (Ahtna Athabascan name: Da lu'itsaa'den) in Alaska, where a lake develops in the higher ablation zone, and drains rapidly early in the melt season. It has also been observed that this lake drainage causes a twofold or threefold speed-up of the main branch, with some acceleration of the lower-lying Loket tributary. This speed-up can be considered a surrogate for a surge, which also initiates in the main branch, while, during times of quiescence, the ice flow on the tributary is dominant. We investigate the effects of varying timing and volume inputs of lake drainage with a focus on its effects beneath the tributary. We find that the response of the glacier depends on the seasonal timing, the amount of water from the draining lake, and its location on or near the margins of the glacier. Results show that an inefficient drainage system is the cause of the glacier speed-up, both when the lake drains rapidly or when there is an extended time in drainage, at any time of the season. The speed signals vary throughout the glacier depending on the location of the lake relative to that of an evolved efficient drainage system.

The most recent report from the Intergovernmental Panel on Climate Change cites ice sheet dynamics as the greatest source of uncertainty for predicting current and future rates of sea level rise. This has prompted the development and use of ice sheet models that are capable of simulating the flow and evolution of ice sheets and their corresponding sea level contribution. In the Arctic, the Greenland ice sheet appears to be responding to a warming climate more quickly than expected. In order to determine sea level contribution from Greenland, it is necessary to capture the regional dynamics of the fast flowing outlet glaciers that drain the ice sheet. This work has developed a novel regional model capable of simulating an outlet glacier, and its associated drainage basin, as a mode of using the Parallel Ice Sheet Model. Specifically, it focuses on modeling the Jakobshavn Isbrae as a demonstration. The Jakobshavn Isbrae is one of the world's fastest flowing outlet glaciers, and accounts for nearly 5% of ice loss from the Greenland Ice Sheet. Additionally, the Jakobshavn Isbrae has been widely studied for several decades, and a wealth of remotely sensed and in situ data is available in this region. These data are used as model input and for model validation. We have completed a parameter study in this work to examine the behavior of the regional model. The purpose of this study was not to tune the model to match observations, but rather to look at the influence of parameter choices on the ice dynamics. Model results indicate that we have identified the subset of the model parameter space that is appropriate for modeling this outlet glacier. Additionally, we are able to produce some of this more interesting features that have been observed at Jakobshavn, such as the development and disintegration of a floating ice tongue and the distribution of observed surface velocities. We validate these model results by comparison with recent spatially rich measurements of ice surface speeds, as well as ice geometry.

Electrostatic structures are observed in various of space environments including the auroral acceleration region, the solar wind region and the magnetosphere. The Bernstein-Greene-Kruskal (BGK) mode, one of the non-linear solutions to the Vlasov-Poisson system, is a potential explanation to these phenomena. Specifically, two dimensional (2D) BGK modes can be constructed through solving the Vlasov-Poisson-Ampère system with the assumption of a uniform ion background. This thesis discusses the existence and features of the 2D BGK modes with kinetic effects from both electrons and ions. Specifically, we construct electron or ion BGK modes with finite temperature ratio between ions and electrons. More general cases, the electron-ion 2D BGK mode with the participation of both non-Boltzmann electron and ion distributions are constructed and analyzed as well.