Yet another caveat to using the Dessler‐Parker‐Sckopke relation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95475/1/jgra16950.pd

Outflow in global magnetohydrodynamics as a function of a passive inner boundary source

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106972/1/jgra50946.pd

The ionospheric source of magnetospheric plasma is not a black box input for global models

Including ionospheric outflow in global magnetohydrodynamic models of near‐Earth outer space has become an important step toward understanding the role of this plasma source in the magnetosphere. Of the existing approaches, however, few tie the outflowing particle fluxes to magnetospheric conditions in a self‐consistent manner. Doing so opens the magnetosphere‐ionosphere system to nonlinear mass‐energy feedback loops, profoundly changing the behavior of the magnetosphere‐ionosphere system. Based on these new results, it is time for the community eschew treating ionospheric outflow as a simple black box source of magnetospheric plasma.Key PointsIonospheric outflow plays a critical role in the magnetosphereThe magnetosphere affects outflowModelers must account for this two‐way relationshipPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133592/1/jgra52677_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133592/2/jgra52677.pd

Statistical analysis of storm-time near-Earth current systems

Currents from the Hot Electron and Ion Drift Integrator (HEIDI) inner magnetospheric model results for all of the 90 intense storms (disturbance storm-time (Dst) minimum \u3c −100 nT) from solar cycle 23 (1996–2005) are calculated, presented, and analyzed. We have categorized these currents into the various systems that exist in near-Earth space, specifically the eastward and westward symmetric ring current, the partial ring current, the banana current, and the tail current. The current results from each run set are combined by a normalized superposed epoch analysis technique that scales the timeline of each phase of each storm before summing the results. It is found that there is a systematic ordering to the current systems, with the asymmetric current systems peaking during storm main phase (tail current rising first, then the banana current, followed by the partial ring current) and the symmetric current systems peaking during the early recovery phase (westward and eastward symmetric ring current having simultaneous maxima). The median and mean peak amplitudes for the current systems ranged from 1 to 3 MA, depending on the setup configuration used in HEIDI, except for the eastward symmetric ring current, for which the mean never exceeded 0.3 MA for any HEIDI setup. The self-consistent electric field description in HEIDI yielded larger tail and banana currents than the Volland–Stern electric field, while the partial and symmetric ring currents had similar peak values between the two applied electric field models

Continued convection and the initial recovery of Dst

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94856/1/grl16086.pd

Exploring the efficacy of different electric field models in driving a model of the plasmasphere

The dynamics of the plasmasphere are strongly controlled by the inner magnetospheric electric field. In order to capture realistically the erosion of the nightside plasmapause and the formation of the drainage plume in a model of the plasmasphere, the electric field must be accurate. This study investigates how well five different electric field models drive the Dynamic Global Core Plasma Model during eight storm periods. The five electric field models are the Volland‐Stern analytic formula with Maynard‐Chen Kp dependence, two versions of the Weimer statistical models (96 and 05), and two versions of the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique using magnetometer and DMSP satellite data. Manually extracted plasmapause locations from images taken by the EUV instrument on the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) satellite, as described by Goldstein et al. (2005), were compared to the simulation results throughout the main phase of the eight events. Three methods of calculating the plasmapause were employed to determine the best fit to EUV data, using the maximum gradient, a constant density contour (fit method), and the location in which the modeled density fell significantly below the specified saturation density for the given radial position (saturation method). It was found that the simulations driven by the Weimer (1996) model produced the best fit overall and that the fit and saturation methods worked best for matching the model results to the observations. Key Points The Weimer [1996] model works quite well for driving the plasmasphere A saturation technique for determining the plasmapause location in introduced Plasmapause determined by IMAGE may not be the steepest gradient in densityPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108010/1/jgra51094.pd

Comment on “Nonlinear response of the polar ionosphere to large values of the interplanetary electric field” by C. T. Russell et al.

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95504/1/jgra16638.pd

Storm-time ring current: model-dependent results

The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT) on 6–7 November 1997 and one intense (SymH minimum of −230 nT) on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM), in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines) forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS) relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.Peer reviewe

On the application of simple rift basin models to the south polar region of Enceladus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94698/1/jgre3058.pd

Storm time equatorial magnetospheric ion temperature derived from TWINS ENA flux

The plasma sheet plays an integral role in the transport of energy from the magnetotail to the ring current. We present a comprehensive study of the equatorial magnetospheric ion temperatures derived from Two Wide‐angle Imaging Neutral‐atom Spectrometers (TWINS) energetic neutral atom (ENA) measurements during moderate to intense (Dstpeak < −60 nT) storm times between 2009 and 2015. The results are validated using ion temperature data derived from the Geotail low‐energy particle energy analyzer and the Los Alamos National Laboratory magnetospheric plasma analyzer. The ion temperatures are analyzed as a function of storm time, local time, and L shell. We perform a normalized superposed epoch analysis of 48 geomagnetic storms and examine the spatial and temporal evolution of the plasma as a function of storm phase. This analysis illustrates the spatial and temporal variation of the ions from the plasma sheet into the inner magnetosphere. We find that the ion temperature increases approaching the storm peak. This enhancement has the largest magnetic local time extent near 12 RE distance downtail.Key PointsWe derive and statistically examine storm time equatorial magnetospheric ion temperatures from TWINS ENA fluxThe TWINS ion temperature data are validated using Geotail and LANL ion temperature dataFor moderate to intense storms the widest (in MLT) peak in nightside ion temperature is found to exist near 12 REPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137478/1/jgra53387.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137478/2/jgra53387_am.pd