Utilizing ‘Austerity Urbanism’ to Understand Berlin's Response to the 2015-16 Influx of Refugees and Asylum Seekers

In 2015, a wave of forcibly displaced people entered Germany in what became known as the ‘refugee crisis.’ Drawing on the case of Berlin — which absorbed a higher number of refugees than any other European city — my thesis will highlight the obstacles to accepting large influxes of refugees in an urban space, specifically relating to housing provisions. At the core of my analysis, I apply the concept of austerity urbanism as an ideological lens to understand Berlin’s state response. I will explain how decades of privatization and budget cuts to social services caused the state and local authorities to lack the capacity to adequately respond to the newcomers’ needs. I conclude that Berlin’s refugee ‘crisis’ originated less so in the arrival of thousands of migrants than in the failure of state institutions.Master of Art

New Solar Wind Diagnostic Using Both in Situ and Spectroscopic Measurements

We develop a new diagnostic technique that utilizes, at the same time, two completely different types of observations—in situ determinations of solar wind charge states and high-resolution spectroscopy of the inner solar corona—in order to study the temperature, density, and velocity of the solar wind as a function of height in the inner corona below the plasma freeze-in point. This technique relies on the ability to calculate the evolution of the ion charge composition as the solar wind escapes the Sun given the wind temperature, density, and velocity profiles as a function of distance. The resulting charge state composition can be used to predict frozen-in charge states as well as spectral line intensities. The predicted spectra and ion charge compositions can be compared with observations carried out when spectrometers and in situ instruments are in quadrature configuration to quantitatively test a set of assumptions regarding density, temperature, and velocity profiles in the low corona. Such a comparison can be used in two ways. If the input profiles are predicted by a theoretical solar wind model, this technique allows the benchmarking of the model. Otherwise, an empirical determination of the velocity, temperature, and density profiles can be achieved below the plasma freeze-in point applying a trial-and-error procedure to initial, user-specified profiles. To demonstrate this methodology, we have applied this technique to a state-of-the-art coronal hole and equatorial streamer model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98555/1/0004-637X_750_2_159.pd

Carbon Ionization Stages as a Diagnostic of the Solar Wind

Oxygen charge states measured by in situ instrumentation have long been used as a powerful diagnostic of the solar corona and to discriminate between different solar wind regimes, both because they freeze in very close to the Sun, and because the oxygen element abundance is comparatively high, allowing for statistically relevant measures. Like oxygen, carbon is also rather abundant and freezes in very close to the Sun. Here, we show an analysis of carbon and oxygen ionic charge states. First, through auditory and Fourier analysis of in situ measurements of solar wind ion composition by ACE /SWICS we show that some carbon ion ratios are very sensitive to solar wind type, even more sensitive than the commonly used oxygen ion ratios. Then we study the evolution of the ionization states of carbon and oxygen by means of a freeze-in code, and find that carbon ions, commonly found in the solar wind, freeze in at comparable coronal distances, while oxygen ions evolve over a much larger range of coronal distances. Finally, we show that carbon and oxygen ion abundance ratios have similar sensitivity to the electron plasma temperature, but the carbon ratios are more robust against atomic physics uncertainties and a better indicator of the temperature of the solar wind source regions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98573/1/0004-637X_744_2_100.pd

Composition Structure of Interplanetary Coronal Mass Ejections From Multispacecraft Observations, Modeling, and Comparison with Numerical Simulations

We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections observed in May 21-23 2007 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation CME initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientation of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process, which could explain the spatial location of the observed iron enhancements just outside the traditional flux rope magnetic signatures and between the two ICMEs. Detailed comparisons between the simulations and data were more complicated, but a sharp increase in high iron charge states in the ACE and STEREO-A data during the second flux rope corresponds well to similar features in the flux cancellation results. We discuss the prospects of this integrated in-situ data analysis and modeling approach to advancing our understanding of the unified CME-to-ICME evolution.Comment: Accepted for submission to The Astrophysical Journa

First Measurements of the Complete Heavy-ion Charge State Distributions of C, O, and Fe Associated with Interplanetary Coronal Mass Ejections

We present the first analysis of the complete charge state distributions of heavy ions in interplanetary coronal mass ejections (CMEs), from singly charged to fully ionized. We develop a novel analysis technique that requires the combination and cross-calibration of two different data sets from the Solar Wind Ion Composition Spectrometer on the Advanced Composition Explorer . The first contains ions of higher charge states, and includes an identification of their mass, mass-per-charge, and energy-per-charge. The second data set contains singly and low-charge ions, and identifies only their mass-per-charge and energy-per-charge. Focusing on C, O, and Fe, we find ionic charge states representative of temperatures from ≤60,000 K to over 5,000,000 K contained within interplanetary CMEs observed near 1 AU. We interpret these data in the context of near-Sun observations of filament material associated with CMEs. We find that singly charged ions are embedded within selected interplanetary CMEs, and we examine their densities and durations. These data thus provide the most unambiguous in situ diagnostic of solar prominence plasma in the heliosphere.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98556/1/0004-637X_751_1_20.pd

Charge State Evolution in the Solar Wind. II. Plasma Charge State Composition in the Inner Corona and Accelerating Fast Solar Wind

In the present work, we calculate the evolution of the charge state distribution within the fast solar wind. We use the temperature, density, and velocity profiles predicted by Cranmer et al. to calculate the ionization history of the most important heavy elements in the solar corona and solar wind: C, N, O, Ne, Mg, Si, S, and Fe. The evolution of each charge state is calculated from the source region in the lower chromosphere to the final freeze-in point. We show that the solar wind velocity causes the plasma to experience significant departures from equilibrium at very low heights, well inside the field of view (within 0.6 R sun from the solar limb) of nearly all the available remote-sensing instrumentation, significantly affecting observed spectral line intensities. We also study the evolution of charge state ratios with distance from the source region, and the temperature they indicate if ionization equilibrium is assumed. We find that virtually every charge state from every element freezes in at a different height, so that the definition of freeze-in height is ambiguous. We also find that calculated freeze-in temperatures indicated by charge state ratios from in situ measurements have little relation to the local coronal temperature of the wind source region, and stop evolving much earlier than their correspondent charge state ratio. We discuss the implication of our results on plasma diagnostics of coronal holes from spectroscopic measurements as well as on theoretical solar wind models relying on coronal temperatures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98586/1/0004-637X_761_1_48.pd

Transient Foreshock Structures Upstream of Mars: Implications of the Small Martian Bow Shock

We characterize the nature of magnetic structures in the foreshock region of Mars associated with discontinuities in the solar wind. The structures form at the upstream edge of moving foreshocks caused by slow rotations in the interplanetary magnetic field (IMF). The solar wind plasma density and the IMF strength noticeably decrease inside the structures' core, and a compressional shock layer is present at their sunward side, making them consistent with foreshock bubbles (FBs). Ion populations responsible for these structures include backstreaming ions that only appear within the moving foreshock, and accelerated reflected ions from the quasi-perpendicular bow shock. Both ion populations accumulate near the upstream edge of the moving foreshock which facilitates FB formation. Reflected ions with hybrid trajectories that straddle between the quasi-perpendicular and quasi-parallel bow shocks during slow IMF rotations contribute to formation of foreshock transients.Comment: Submitted to Geophysical Research Letter

A Global Two-temperature Corona and Inner Heliosphere Model: A Comprehensive Validation Study

The recent solar minimum with very low activity provides us a unique opportunity for validating solar wind models. During CR2077 (2008 November 20 through December 17), the number of sunspots was near the absolute minimum of solar cycle 23. For this solar rotation, we perform a multi-spacecraft validation study for the recently developed three-dimensional, two-temperature, Alfvén-wave-driven global solar wind model (a component within the Space Weather Modeling Framework). By using in situ observations from the Solar Terrestrial Relations Observatory (STEREO) A and B , Advanced Composition Explorer ( ACE ), and Venus Express , we compare the observed proton state (density, temperature, and velocity) and magnetic field of the heliosphere with that predicted by the model. Near the Sun, we validate the numerical model with the electron density obtained from the solar rotational tomography of Solar and Heliospheric Observatory /Large Angle and Spectrometric Coronagraph C2 data in the range of 2.4 to 6 solar radii. Electron temperature and density are determined from differential emission measure tomography (DEMT) of STEREO A and B Extreme Ultraviolet Imager data in the range of 1.035 to 1.225 solar radii. The electron density and temperature derived from the Hinode /Extreme Ultraviolet Imaging Spectrometer data are also used to compare with the DEMT as well as the model output. Moreover, for the first time, we compare ionic charge states of carbon, oxygen, silicon, and iron observed in situ with the ACE /Solar Wind Ion Composition Spectrometer with those predicted by our model. The validation results suggest that most of the model outputs for CR2077 can fit the observations very well. Based on this encouraging result, we therefore expect great improvement for the future modeling of coronal mass ejections (CMEs) and CME-driven shocks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98628/1/0004-637X_745_1_6.pd

Spatially Dependent Heating and Ionization in an ICME Observed by Both ACE and Ulysses

The 2005 January 21 interplanetary coronal mass ejection (ICME) observed by multiple spacecraft at L1 was also observed from January 21-February 4 at Ulysses (5.3 AU). Previous studies of this ICME have found evidence suggesting that the flanks of a magnetic cloud like structure associated with this ICME were observed at L1 while a more central cut through the associated magnetic cloud was observed at Ulysses . This event allows us to study spatial variation across the ICME and relate it to the eruption at the Sun. In order to examine the spatial dependence of the heating in this ICME, we present an analysis and comparison of the heavy ion composition observed during the passage of the ICME at L1 and at Ulysses . Using SWICS, we compare the heavy ion composition across the two different observation cuts through the ICME and compare it with predictions for heating during the eruption based on models of the time-dependent ionization balance throughout the event.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98582/1/0004-637X_760_2_105.pd

CME Evolution in the Structured Heliosphere and Effects at Earth and Mars During Solar Minimum

The activity of the Sun alternates between a solar minimum and a solar maximum, the former corresponding to a period of "quieter" status of the heliosphere. During solar minimum, it is in principle more straightforward to follow eruptive events and solar wind structures from their birth at the Sun throughout their interplanetary journey. In this paper, we report analysis of the origin, evolution, and heliospheric impact of a series of solar transient events that took place during the second half of August 2018, i.e. in the midst of the late declining phase of Solar Cycle 24. In particular, we focus on two successive coronal mass ejections (CMEs) and a following high-speed stream (HSS) on their way towards Earth and Mars. We find that the first CME impacted both planets, whilst the second caused a strong magnetic storm at Earth and went on to miss Mars, which nevertheless experienced space weather effects from the stream interacting region (SIR) preceding the HSS. Analysis of remote-sensing and in-situ data supported by heliospheric modelling suggests that CME--HSS interaction resulted in the second CME rotating and deflecting in interplanetary space, highlighting that accurately reproducing the ambient solar wind is crucial even during "simpler" solar minimum periods. Lastly, we discuss the upstream solar wind conditions and transient structures responsible for driving space weather effects at Earth and Mars.Comment: 27 pages, 7 figures, 1 table, accepted for publication in Space Weathe