Bulletin of the American Physical Society
Joint Fall 2017 Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the Society of Physics Students
Volume 62, Number 16
Friday–Saturday, October 20–21, 2017; The University of Texas at Dallas, Richardson, Texas
Session B7: Space Physics |
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Chair: David Lary, University of Texas at Dallas Room: JSOM 1.107 |
Friday, October 20, 2017 2:45PM - 3:09PM |
B7.00001: New two-dimensional radar observations of equatorial spread F at the Jicamarca Radio Observatory Invited Speaker: Fabiano Rodrigues Equatorial spread-F (ESF) is the general name given, for historical reasons, to low-latitude disturbances in the Earth's ionospheric plasma density and their signatures in different types of ionospheric sensors. The study of ESF is motivated by a better understanding of fundamental space plasma dynamics. It is also motivated by the impact of ESF on the propagation of signals used in civil and military applications. Significant contributions to our understanding of ESF dynamics have been made by ground-based radar observations at the Jicamarca Radio Observatory in Peru. The observatory is equipped with radar systems capable of making observations of the quiescent and turbulent states of the ionospheric plasma. Until recently, however, a steerable radar capability was not available to Jicamarca, which limited the observations to a few degrees within zenith. In 2014, a 14-panel version of the advanced modular incoherent scatter radar (AMISR-14) system was deployed at Jicamarca. AMISR is a modular, mobile radar facility with electronic steering capability to be used for studies of the Earth's upper atmosphere and space weather. A full AMISR-14 consisting of 128 building-block like (TX/RX) panels is capable of making measurements of the quiescent plasma and infer ionospheric parameters such as ion and electron temperatures, electron density, ion composition, and ion velocity. While AMISR-14 was not expected to be capable of making such measurements, tests were performed to investigate its ability to detect echoes from ESF irregularities. Two campaigns of AMISR-14 observations of ESF were performed at Jicamarca; one in August 2014 and another in July/August 2016. Analyses of the measurements show that not only ESF echoes can be detected by AMISR, but the dynamics of the ESF events in the magnetic equatorial plane can be inferred from a mode that takes advantage of the beam steering capability. In this talk, we will provide a brief introduction to ESF, followed by a description of ESF measurements using radar systems. We will then present examples of the new measurements made with AMISR-14. The observations are discussed in terms of ESF theory, and simultaneous observations made by collocated instruments. [Preview Abstract] |
Friday, October 20, 2017 3:09PM - 3:21PM |
B7.00002: The Diffraction of Waves through the Polar Ionosphere Russell Stoneback, Rod Heelis, Angeline Burrell The Earth and Ionosphere form a resonant electromagnetic structure that produces the well known Schumann Resonances starting around 8 Hz. These resonances were predicted under the assumption that both the Earth and Ionosphere have large horizontal conductivities forming a concentric spherical capacitor. It is also well known that at high latitudes the vertical orientation of the geomagnetic field results in a very low horizontal conductivity. We present a model of electromagnetic wave interactions between the Earth and Ionosphere that includes this significant reduction in conductivity at high latitudes, effectively forming a concentric spherical capacitor with holes (apertures) cut out of the cavity at high latitudes. Electromagnetic waves in space incident upon this low conductivity region, surround by conductive ionosphere (same boundary conditions as an aperture in metal), will diffract through the polar ionosphere. We will present an overview of the model, including comparisons to measured atmosphere/solar wind interactions. [Preview Abstract] |
Friday, October 20, 2017 3:21PM - 3:33PM |
B7.00003: On the development of a new model of low-latitude ionospheric electric fields Sam Shidler, Fabiano Rodrigues Electric fields play an important role in ionospheric dynamics as they drive the transport of ionospheric plasma at F-region heights. Measurements of ionospheric electric fields at a fixed location have been made by ground-based radar systems. Global observations of ionospheric electric fields have also been made by sensors on LEO satellites. We have been working towards the development of a two-dimensional numerical model of the ionospheric electric potential at low latitudes. The model will be used to aid our interpretation of electric fields measurements including those to be made by the upcoming COSMIC-2 and ICON satellite missions. The set of two-dimensional equations used to generate the numerical model are obtained by taking into consideration the high conductivity along magnetic field lines. During this talk, we will present and discuss the mathematical foundation of the model and provide a description of the necessary input parameters. Initial results of our calculation of model components will be presented using, as drivers, readily available models of the ionosphere (IRI16), and thermosphere (HWM14, NRLMSISE00). The results will be discussed and potential future efforts will be described. [Preview Abstract] |
Friday, October 20, 2017 3:33PM - 3:45PM |
B7.00004: Dayside Magnetopause Location Comparisons during Interplanetary Magnetic Field Oscillations Richard Bonde, Jiangyan Wang, Ramon Lopez Earth's magnetic field is shaped by the solar wind; a steady yet nonuniform stream of plasma emanating from the Sun. The shape of Earth's magnetic field is called the magnetosphere. The solar wind carries out into space the Sun's magnetic field, called the interplanetary magnetic field (IMF). When the IMF embedded in the solar wind encounters Earth's magnetic field, a boundary forms between Earth's magnetosphere and the IMF, called the magnetopause. The dayside magnetopause's location depends on upstream solar wind conditions, most significantly the direction of the IMF. When the IMF is directed southward, the dayside magnetopause moves inward and this is generally referred to as magnetopause erosion. Several studies have examined the effects of steady state IMF conditions on the magnetopause location. This study examined the effects of IMF oscillations as are more realistic in the solar wind. We used a magnetohydrodynamic (MHD) model to determine the magnetopause movement under fluctuating IMF conditions. We present the MHD results of the predicted dayside magnetopause location and compare them with satellite data. [Preview Abstract] |
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