Physics and Astronomy Space Plasma Seminar

Dr Brett Carter, Victorian Postdoctoral Research Fellow, SPACE Research Centre, RMIT University, Institute for Scientific Research, Boston College

May 27, 2014
4 pm - 5 pm
Location
Wilder 115
Sponsored by
Physics & Astronomy Department
Audience
Public
More information
Tressena Manning
603-646-2854

Title: "Using the TIEGCM to Model the Day-to-Day Occurrence of Equatorial Plasma Bubbles"

Abstract: Equatorial Plasma Bubbles (EPBs) are regions of low electron density plasma in the ionosphere that commonly develop shortly after local sunset at low latitudes. The small-scale plasma structures generated by the formation of EPBs induce random fluctuations (i.e., scintillation) in the phase and amplitude of the trans-ionospheric radio waves used in various applications; e.g., Global Navigation Satellite Systems and satellite telecommunications. As such, the ability to reliably predict such disturbances is sort by a wide range of industries and users of space-based applications. Whilst the occurrence climatology of EPBs is rather well understood from decades of global observations, describing the day-to-day variability in the occurrence of Equatorial Plasma Bubbles (EPBs) has been a significant challenge over several decades. Presented is a recent study of the daily quiet-time EPB variability in the Southeast Asian region that has found that the daily EPB occurrence can largely be replicated using the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) to calculate variations in the Rayleigh-Taylor (R-T) linear instability growth rate. It is shown that relatively minor changes in the level of geomagnetic activity, as parameterized by the Kp index, can have an important influence on whether or not the formation of EPBs occurs. The TIEGCM is also used to model the R-T growth rate variability for five additional ionospheric scintillation monitoring stations spanning from the American to the Southeast Asian regions, over a 2-month equinoctial period during the following solar maximum. The result is that for seasons characterized by favorable EPB growth conditions, the TIEGCM is capable of identifying days for which EPB growth has been suppressed due to minor increases in geomagnetic activity. In addition, observed and modeled upward plasma drift indicates that the pre-reversal enhancement best scales linearly with Kp from ~ 3 hrs prior. This time delay indicates that minor changes in geomagnetic activity influence the thermospheric wind fields that controls the strength of the low-latitude F-region dynamo some 3 hours later. The most significant result is that these small changes in Kp significantly control the daily EPB occurrence variability, which paves the way for us to develop reliable day-to-day EPB occurrence predictions in the not-too-distant future.

Location
Wilder 115
Sponsored by
Physics & Astronomy Department
Audience
Public
More information
Tressena Manning
603-646-2854