Browsing by Author "Beyene, Bizuayehu Addisie"

Now showing 1 - 1 of 1
  • Thumbnail Image
    ItemOpen Access
    Unexpected Field-Aligned Structure in Equatorial Plasma Bubbles
    (2024-07-10) Beyene, Bizuayehu Addisie; Knudsen, David; Skone, Susan; Brown, Jo-Anne Catherine; Ouyed, Rachid; Plume, Rene
    Equatorial plasma bubbles, commonly known as EPBs, are field-aligned ionospheric irregularities in the bottomside of the F-region equatorial ionosphere generated due to the RayleighTaylor instability. EPBs affect radio waves and are sources of error for Global Navigation Satellite Systems (GNSS) due to their effect on the amplitude and phase of the satellite signal. In this thesis, 2 Hz plasma density data from 2014 to 2023 from the Swarm satellite mission orbiting nearly parallel to geomagnetic field lines is used to study equatorial plasma bubble characteristics such as bubble length and occurrence frequency. A moving average iterative smoothing technique over different window sizes was used to extract the smoothed background data, which in turn was used to compute the relative plasma density that is used to identify bubble boundaries based on a predefined threshold value. The results are compared with data from the Communications/Navigation Outage Forecasting System (C/NOFS) satellite, which cut across bubbles while flying eastward. According to the results obtained, plasma bubbles appear after sunset until before dawn which is in agreement with previous results and the existing theory. Although it is commonly believed that EPBs extend along the entire geomagnetic field line, the results in this study show similar degrees of structure in both Swarm and C/NOFS data, despite their orthogonal directions of travel. This suggests a much higher degree of structuring along B than previously recognized and strongly suggests a heretofore unidentified source of severe plasma structure parallel to B.