A5006385517- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Earthquake Detection and Analysis
- GNSS positioning and interference
- Meteorological Phenomena and Simulations
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Photovoltaic System Optimization Techniques
- Tropical and Extratropical Cyclones Research
- Solar Thermal and Photovoltaic Systems
- Gas Dynamics and Kinetic Theory
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Heat Transfer and Boiling Studies
- Planetary Science and Exploration
- solar cell performance optimization
- Wind and Air Flow Studies
- Fluid Dynamics and Turbulent Flows
- earthquake and tectonic studies
- Lattice Boltzmann Simulation Studies
- Oceanographic and Atmospheric Processes
Dartmouth College
2010-2021
Preston's College
2020
Dartmouth Hospital
2014
The sawtooth mode of convection Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations geospace, we have shown that ionospheric O(+) outflows can generate oscillations. As outflowing ions fill inner magnetosphere, their pressure distends nightside magnetic field. When outflow fluence exceeds threshold, field tension cannot confine accumulating fluid; an O(+)-rich plasmoid ejected,...
Observed distributions of high-speed plasma flows at distances 10 to 30 Earth radii (R(E)) in Earth's magnetotail neutral sheet are highly skewed toward the premidnight sector. The a product magnetic reconnection process that converts energy stored into kinetic and thermal energy. We show, using global numerical simulations, electrodynamic interaction between magnetosphere ionosphere produces an asymmetry consistent with observed nightside plasmasheet accompanying ionospheric convection....
Abstract General methods for improving the specification of electron precipitation in global simulations are described and implemented Lyon‐Fedder‐Mobarry (LFM) simulation model, quality its predictions is assessed. LFM's existing diffuse monoenergetic models improved, new developed lower energy, broadband, direct‐entry cusp precipitation. The LFM results combined plus exhibit a quadratic increase hemispheric power as intensity solar wind driving increases, contrast with prediction from...
Jupiter’s slow dayside magnetic merging and fast rotation produce an unusual topology that can explain its polar aurora.
It is widely accepted that the ionosphere an important source of ions in magnetosphere and until recently this population has largely been neglected from many global simulations. In study, a causally regulated cusp O + outflow added to multifluid version Lyon‐Fedder‐Mobarry (LFM) simulation. The algorithm uses empirical relationships regulate flux with further conditioning isolate spatially dynamic cusp. impact on magnetosphere‐ionosphere (MI) system investigated for moderate storm 31 August...
The mechanisms by which ionospheric O + stretches the plasma sheet causing variations in polar cap flux during magnetospheric sawtooth substorms are investigated using multi‐fluid Lyon‐Fedder‐Mobarry simulation code. outflow is induced Alfvénic Poynting flowing to low altitude expansion and growth phases. fluid populates causes it stretch tailward response increased mass density. thus functions as a feedback loop magnetosphere‐ionosphere system wherein ions released phase alter configuration...
The generation of Alfvénic Poynting flux in the central plasma sheet and its polar distribution at low altitude are studied using three dimensional global simulations solar wind‐magnetosphere‐ionosphere interaction. A 24‐hour event simulation (4–5 Feb 2004) driven by wind interplanetary magnetic field data reproduces morphology measured Polar satellite, including dawn‐dusk asymmetry. Controlled show that asymmetry is regulated spatial variation ionospheric conductance. disappears when...
Magnetosphere sawtooth oscillations have been observed during interplanetary coronal mass ejection (ICME) events, when the solar wind conditions are relatively steady, and periods magnetic field (IMF) fluctuates between northward southward, as stream interaction regions (SIR). The impact of ionospheric outflow on ICME‐driven 18 April 2002 SIR‐driven 24 October events is investigated using a multifluid adaptation Lyon‐Fedder‐Mobarry global simulation. mechanisms that generate by comparing...
Abstract Ability to quantify variations in magnetic field topology and density within Jupiter's magnetosphere is an important step understanding the overall structure dynamics. The Juno spacecraft has provided a rich data set dawnside magnetosphere. recent Grid Agnostic MHD for Extended Research Applications (GAMERA) global simulation study by Zhang et al. (2021, https://doi.org/10.1126/sciadv.abd1204 ) showed highly structured plasmadisc with closed lines mapped between outer dawn‐tail...
Enhancements in F ‐region electron density and temperature bottomside Pedersen conductivity caused by soft precipitation are shown to enhance the Joule heating per unit mass of thermosphere at altitudes. The results derived from coupled magnetosphere‐ionosphere‐thermosphere model (CMIT) including two types causally specified precipitation—direct‐entry cusp Alfvén‐wave induced, broadband precipitation—the effects which self‐consistently included for first time a global simulation model....
Abstract This paper investigates the effects of magnetospheric mass loading on control dayside magnetic reconnection using global simulations. The study iys motivated by a recent debate whether integrated rate is solely controlled local processes (local‐control theory) or merging (global‐control theory). local‐control theory suggests that plasma parameters. global‐control argues determined net force acting flow in magnetosheath rather than microphysics. Controlled numerical simulations...
In this paper we compare observations of the high‐latitude cusp from DMSP data to simulations conducted using Lyon‐Fedder‐Mobarry (LFM) global magnetosphere simulation. The LFM simulation is run for 31 August 2005 02 September moderate storm, which solar wind exhibits a wide range conditions that enable statistical representation be obtained. location identified traditional magnetic depression and plasma density enhancement at high altitude. A new diagnostic parallel ion number flux also...
Abstract We have conducted a series of controlled numerical simulations to investigate the response dayside reconnection idealized, ionosphere‐sourced mass loading processes determine whether they affect integrated rate. Our simulation results show that coupled solar wind‐magnetosphere system may exhibit both local and global control behaviors depending on amount loading. With small loading, changes in rate affects magnetosheath properties only weakly geoeffective length upstream wind is...
Abstract The efficiencies of pathways thermospheric heating via soft electron precipitation in the dayside cusp region are investigated using coupled magnetosphere‐ionosphere‐thermosphere model (CMIT). Event‐based data‐model comparisons show that CMIT is capable reproducing mass density variations measured by CHAMP satellite during both quite and active periods. During 24 August 2005 storm event ( K p = 6−) while intense Joule rate occurs polar region, including important for accurately...
Abstract We summarize the results of a study on impact plasmaspheric plumes dayside reconnection using three‐dimensional magnetospheric simulation code. find that mass loading flux tubes slows local rates, though not as much predicted by Borovsky et al. (2013) due to differences in how well Cassak‐Shay theory matches configurations with and without plumes. Additionally, we some circumstances activity is enhanced either side plumes, which moderates its total rate. These provide evidence have...
The effects of solar wind driving conditions on the polar distribution large‐scale, nondispersive Alfvénic Poynting flux at low altitude during steady magnetosphere convections are studied using three‐dimensional global simulations wind‐magnetosphere‐ionosphere interaction. Results from 18 test driven by upstream (SW) and interplanetary magnetic field (IMF) used to investigate relationship between SW/IMF low‐altitude signatures large‐scale flux. When IMF is southward, intensity increases,...
Abstract How oxygens escape from Venus has long been a fundamental but controversial topic in the planetary research. Among various key mechanisms, Kelvin‐Helmholtz instability (KHI) suggested to play an important role oxygen ion Venus. Limited by either scarce in‐situ observations or simplified theoretical estimations, mystery of process associated with KHI is still unsettled. Here we present first three‐dimensional configuration at global multifluid magnetohydrodynamics model, showing...
The Multifluid‐Lyon‐Fedder‐Mobarry (MFLFM) global simulation model incorporating an ionospheric cusp O + outflow based on empirical relation between downward DC Poynting flux and regulated by the precipitating electron number ( F en ) is used to simulate 31 August 2005 storm. A baseline run original solar wind data contrasted against a case where dynamic pressure P dyn artificially adjusted see what effects this variable has fluence generated in model. Consistent with data, it found that...
Abstract This paper investigates a possible physical mechanism of the observed dayside high‐latitude upper thermospheric wind using numerical simulations from coupled magnetosphere‐ionosphere‐thermosphere (CMIT) model. Results show that CMIT model is capable reproducing unexpected afternoon equatorward winds in thermosphere by High altitude Interferometer WIND observation (HIWIND) balloon. Models lack adequate coupling produce poleward winds. The modeling study suggests ion drag driven...
Abstract Jupiter's magnetosphere exhibits notable distinctions from the terrestrial magnetosphere. The structure and dynamics of dawnside can be characterized as a competition between internally driven sunward flow solar wind‐driven tailward flow. During prime mission, Juno acquired extensive data dawn to midnight, sampling magnetodisc higher latitude regions. Numerical moments Jovian Auroral Distributions Experiment (JADE‐I) plasma (ion) instrument revealed mid‐latitude region...
Abstract Earthward propagating plasmoids in the Earth's magnetotail have been observed by satellites. Using a multifluid global magnetosphere simulation, earthward are reproduced when ionospheric O + outflow is included simulation. Controlled simulations show that without outflow, generated during substorm‐steady magnetospheric convection cycle only propagate tailward. With can be induced through modification of reconnection at multiple X lines. When lines form magnetotail, may trapped...
Abstract Ionospheric outflow plays an important role in the mass coupling between ionosphere and coupled solar wind‐magnetosphere system. Previous modeling studies have shown that outflowing ionospheric ions may induce magnetospheric sawtooth oscillations through loading of magnetotail, stretching magnetic field lines, reducing nightside reconnection. The spatial distribution polar cap these simulation produces significant auroral oval lacks a distinct cusp source. Thus, question arises...
Abstract A method for specifying low‐altitude or inner boundary conditions that conserve low‐frequency, magnetic field‐aligned, electromagnetic energy flux across the in global magnetospheric magnetohydrodynamics (MHD) models is presented. The single‐fluid Lyon‐Fedder‐Mobarry (LFM) model used to verify this method, with comparisons between simulations using LFM's standard hardwall and new flux‐conserving conditions. Identical idealized upstream solar wind interplanetary field same constant...