Browsing by Subject "ULF Waves"
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Item Fortran code for modeling the propagation of ULF waves in a 3-dimensional dipole magnetosphere(2020-04-13) Lysak, Robert L; Waters, Colin; Sciffer, Murray; lysak001@umn.edu; Lysak, Robert L; University of Minnesota Space Physics GroupThis code allows for the modeling of Ultra-Low-Frequency (ULF) waves in the Earth's magnetosphere. It has been used in a number of publications and presentations at conferences. It takes a prescribed driver in the form of a compression at the outer boundary and follows the propagation of the waves through the magnetosphere and to the ground. The output consists of files each containing snapshots of one component of the electromagnetic field at all points in the simulation volume at an instant of time, in addition to files containing background information such as the Alfven speed profile throughout the simulation.Item Modeling Pc4 Pulsations in Two and a Half Dimensions with Comparisons to Van Allen Probes Observations(2016-04) McEachern, CharlesField line resonances — that is, Alfvén waves bouncing between the northern and southern foot points of a geomagnetic field line — serve to energize magnetospheric particles through drift-resonant interactions, carry energy from high to low altitude, induce currents in the magnetosphere, and accelerate particles into the atmosphere. Wave structure and polarization significantly impact the execution these roles. The present work showcases a new two and a half dimensional code, Tuna, ideally suited to model FLRs, with the ability to consider large-but-finite azimuthal modenumbers, coupling between the poloidal, toroidal, and compressional modes, and arbitrary harmonic structure. Using Tuna, the interplay between Joule dissipation and poloidal-to-toroidal rotation is considered for both dayside and nightside conditions. An attempt is also made to demystify giant pulsations, a class of FLR knows for its distinctive ground signatures. Numerical results are supplemented by a survey of ∼700 FLRs using data from the Van Allen Probes, the first such survey to characterize each event by both polarization and harmonic. The combination of numerical and observational results suggests an explanation for the disparate distributions observed in poloidal and toroidal FLR events.Item Updated Fortran program for modeling ULF waves in a three-dimensional magnetosphere(2022-05-19) Lysak, Robert L; lysak001@umn.edu; Lysak, Robert L; University of Minnesota School of Physics and Astronomy Space Physics GroupThis is the update of a three-dimensional code in dipole geometry for modeling Ultra-Low-Frequency (ULF) waves. The previous version is at https://doi.org/10.13020/d1g7-c676. This code has been used in a study of so-called Pi2 pulsations in the magnetosphere, which are waves with a period of 1-2 minutes that are commonly observed during substorms. This code has been used in conjunction with analysis of data from the Van Allen Probes mission.