Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Temporal variations of the ion convection boundary

Inter-Hemispheric Asymmetries in the High-Latitude Electrodynamic Forcing and the Thermosphere During the October 8-9, 2012 Geomagnetic Storm: An Integrated Data-Model Investigation

Y. Hong, Y. Deng, Q. Zhu, A. Maute, M. Hairston, C. Sheng, D. Welling, R. Lopez utilize field-aligned currents (FACs) obtained from the Active Magnetosphere and Planetary Electrodynamics Response Experiment data set to specify the high-latitude electric potential in the Global Ionosphere and Thermosphere Model (GITM) to examine the IHAs in the IT system during the 8-9 October 2012 storm.

Global RMSE between truth and experiment results

Specifying Satellite Drag Through Coupled Thermosphere-Ionosphere Data Assimilation of Radio Occultation Electron Density Profiles Publication: Space Weather

Nicholas Dietrich,  Tomoko Matsuo, Chih-Ting Hsu for the first time, successfully estimate helium compositions with plasma observations, where helium has virtually no observations and becomes dominant at high altitudes. Their study further develops the potential use of a large and growing source of plasma data to predict the Earth orbital environment. 

summation of growth rates of the upper hybrid instability for a variety of wavelengths

The photoelectron driven upper hybrid instability as the cause of 150 km echoes

Nicholas Pedatella discusses strong, unexplained echoes returning from altitudes of 130–170 km in the atmosphere; how all radars work by reflecting radio waves off a target and measuring the returned signal. This region (130–170 km) in the upper atmosphere is likely to create and maintain a specific set of plasma waves that act as a coherent structure for radar measurements. 

Near Earth interplanetary electric field, IMF Bz from ACE, GUVI dayside, GUVI O/N2 column density

FUV Observations of Variations in Thermospheric Composition and Topside Ionospheric Density During the November 2004 Magnetic Superstorm

Y. Zhang, L. Paxton, C. Huang, and WWang, observe that the 135.6 nm radiances clearly showed a signature of ionospheric equatorial arcs and their variations during the November 2004 magnetic superstorm. When an intense eastward Interplanetary Electric Field (IEF) occurred, the dayside equatorial arcs were enhanced and their latitude separation increased.

Altitudinal and Latitudinal Images

Neutral composition and temperature responses to the 20-21 November 2003 Superstorm from GUVI dayside limb measurements

Tingting Yu, Wenbin Wang, Zhipeng Ren, and Jia Yue use TIMED/GUVI limb measurements of FUV airglow emission to investigate thermospheric composition and temperature responses to the 20-21 November 2003 (day of year (DOY) 324 and 325) superstorm. The storm-time composition and temperature responses were global and evolved continuously as the storm progressed.

Simulations of hemispherically integrated Joule heating [GW] polewardd

Magnetosphere-ionosphere coupling via prescribed field-aligned current simulated by the TIEGCM

A. Maute, A.D. Richmond, G. Lu, D. Knipp, Y. Shi, B. Anderson assert that the magnetosphere-ionosphere (MI) coupling is crucial in modeling the thermosphere-ionosphere (TI) response to geomagnetic activity. They introduce a new method  using observed FAC and solve for the interhemispherically asymmetric electric potential distribution. 

3D MHD simulation of the emergence of a twisted magnetic flux tube

Validation of the PDFI SS method for electric field inversions using magnetic flux emergence simulations

A.N. Afanasyev, M.D. Kazachenko, Y. Fan, G.H. Fisher, and B. Tremblay further validate the PDFI SS method, using approximately one–hour long MHD simulation data of magnetic flux emergence from the upper convection zone into the solar atmosphere. They reconstruct photo- spheric electric fields and calculate the Poynting flux, and compare those to the actual values from the simulations.

Coupled model of thermosphere-ionosphere-magnetosphere system

Thermospheric Impact on the Magnetosphere through Ionospheric Outflow

Kevin Pham, William Lotko, Roger Varney, Binzheng Zhang, Jing Liu have taken a key step in evaluating the importance of ionospheric outflows relative to electrodynamic coupling in the thermosphere’s impact on geospace dynamics.  Their simulation results identify a variety of observed magnetospheric features that are attributable directly to the thermosphere’s material influence.

Two flux surfaces pressed into contact

The topological nature of the Parker Magnetostatic Theorem

B. C. Low reviews the two-plate initial boundary-value problem of Parker, treating the relaxation of a 3D magnetic field prescribed with an arbitrary topology to a terminal force-free field in a cold, viscous, electrically perfect fluid-conductor. Anchored by their foot-points at the perfectly conducting rigid plates, the relaxing field preserves its topology.