Bibliography

Hemispheric differences in the response of the upper atmosphere to the August 2011 geomagnetic storm: A simulation study

Using a three-dimensional nonhydrostatic general circulation model, we investigate the response of the thermosphere–ionosphere system to the 5–6 August 2011 major geomagnetic

Yi\ugit, Erdal; Frey, Harald; Moldwin, Mark; Immel, Thomas; Ridley, Aaron;

Published by: Journal of Atmospheric and Solar-Terrestrial Physics      Published on:

YEAR: 2016     DOI: 10.1016/j.jastp.2015.10.002

Importance of capturing heliospheric variability for studies of thermospheric vertical winds

Using the Global Ionosphere Thermosphere Model with observed real-time heliospheric input data, the magnitude and variability of thermospheric neutral vertical winds are investigated. In order to determine the role of variability in the Interplanetary Magnetic Field (IMF) and solar wind density on the neutral wind variability, the heliospheric input data are smoothed. The effects of smoothing the IMF and solar wind and density on the vertical winds are simulated for the cases of no smoothing, 5-minute, and 12-minute smoothing. Various vertical wind acceleration terms, such as the nonhydrostatic acceleration, are quantified. Polar stereographic projections of the variabilities of vertical wind and ion flows are compared to highlight existing correlations. Overall, the smoother, that is, the less variable the IMF and solar wind parameters are, the weaker are the magnitude and the variability of the thermospheric vertical winds. Weaker IMF variability leads to smaller variability in ion flows, which in turn negatively impacts the variability and the magnitude of Joule heating. Small-scale temporal variation of the vertical wind acceleration, and thus the variability of the vertical wind, is dominated by the nonhydrostatic term that is controlled primarily by the temporal variation of the Joule heating, which in turn is related to ion flow variations that are shaped by the IMF in the high-latitude thermosphere. Wavelet analysis of the vertical wind data shows that gravity waves of \~5 and \~10-minute periods are more prominent when the model is run with high-resolution real-time IMF and solar wind data. Better capturing of the temporal variation of the IMF and solar wind parameters is crucial for modeling the variability and magnitude of thermospheric vertical winds.

Erdal, Yi\u; Ridley, Aaron; Moldwin, Mark;

Published by: Journal of Geophysical Research      Published on: 07/2012

YEAR: 2012     DOI: 10.1029/2012JA017596

gravity waves; interplanetary magnetic field; Joule heating; magnetosphere-ionosphere-thermosphere coupling; nonhydrostatic general circulation model; vertical wind variability

Longitudinal differences of ionospheric vertical density distribution and equatorial electrodynamics

Accurate estimation of global vertical distribution of ionospheric and plasmaspheric density as a function of local time, season, and magnetic activity is required to improve the operation of space-based navigation and communication systems. The vertical density distribution, especially at low and equatorial latitudes, is governed by the equatorial electrodynamics that produces a vertical driving force. The vertical structure of the equatorial density distribution can be observed by using tomographic reconstruction techniques on ground-based global positioning system (GPS) total electron content (TEC). Similarly, the vertical drift, which is one of the driving mechanisms that govern equatorial electrodynamics and strongly affect the structure and dynamics of the ionosphere in the low/midlatitude region, can be estimated using ground magnetometer observations. We present tomographically reconstructed density distribution and the corresponding vertical drifts at two different longitudes: the East African and west South American sectors. Chains of GPS stations in the east African and west South American longitudinal sectors, covering the equatorial anomaly region of meridian \~37\textdegreeE and 290\textdegreeE, respectively, are used to reconstruct the vertical density distribution. Similarly, magnetometer sites of African Meridian B-field Education and Research (AMBER) and INTERMAGNET for the east African sector and South American Meridional B-field Array (SAMBA) and Low Latitude Ionospheric Sensor Network (LISN) are used to estimate the vertical drift velocity at two distinct longitudes. The comparison between the reconstructed and Jicamarca Incoherent Scatter Radar (ISR) measured density profiles shows excellent agreement, demonstrating the usefulness of tomographic reconstruction technique in providing the vertical density distribution at different longitudes. Similarly, the comparison between magnetometer estimated vertical drift and other independent drift observation, such as from VEFI onboard Communication/Navigation Outage Forecasting System (C/NOFS) satellite and JULIA radar, is equally promising. The observations at different longitudes suggest that the vertical drift velocities and the vertical density distribution have significant longitudinal differences; especially the equatorial anomaly peaks expand to higher latitudes more in American sector than the African sector, indicating that the vertical drift in the American sector is stronger than the African sector.

Yizengaw, E.; Zesta, E.; Moldwin, M.; Damtie, B.; Mebrahtu, A.; Valladares, C.; Pfaff, R.;

Published by: Journal of Geophysical Research      Published on: 07/2012

YEAR: 2012     DOI: 10.1029/2011JA017454

Tomography; vertical drift

On the causes of plasmaspheric rotation variability: IMAGE EUV observations

Galvan, David; Moldwin, Mark; Sandel, Bill; Crowley, Geoff;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2010     DOI:

Multi-instrument observations of the ionospheric and plasmaspheric density structure

Yizengaw, E; Moldwin, MB;

Published by:       Published on:

YEAR: 2008     DOI: