On the Properties of and Ionospheric Conditions Associated With a Mid‐Latitude Scintillation Event Observed Over Southern United States. Issue 6 (22nd June 2021)

• Record Type: Journal Article
• Authors: Rodrigues, F. S.; Socola, J. G.; Moraes, A. O.; Martinis, C.; Hickey, D. A.
• Is Part Of: Space weather. Volume 19:Issue 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-22
• Subjects: scintillation -- ionosphere -- GNSS -- mid‐latitude -- irregularities; Space environment -- Periodicals; 551.509992
• DOI: 10.1029/2021SW002744
• Languages: English
• ISSNs: 1542-7390

Abstract

Abstract: While low and high‐latitude ionospheric scintillation have been extensively reported, significantly less information is available about the properties of and conditions leading to mid‐latitude scintillations. Here, we report and discuss scintillation observations made in the Southern United States (UT Dallas, 32.99°N, 96.76°W, 43.2°N dip latitude) on June 1st, 2013. The measurements were made by a specialized dual‐frequency GPS‐based scintillation monitor which allowed us to determine main properties of this mid‐latitude scintillation event. Additionally, simultaneous airglow observations and ionospheric total electron content (TEC) maps provided insight on the conditions leading to observed scintillations. Moderate amplitude scintillations (S4 >∼0.4) occurred in both L1 and L2C signals, and severe (S4 > ∼0.8) events occurred in L2C signals at low (<30°) elevation angles. Phase scintillation accompanied amplitude fadings, with maximum σϕ values exceeding 0.5 radians in L2C. We also show that the observed phase scintillation magnitudes increased with amplitude scintillation severity. Decorrelation times were mostly between 0.25 and 1.25 s, with mean value around 0.65 s for both L1 and L2C. Frequency scaling of S4 matched fairly well the predictions of weak scattering theory but held for observations of moderate and strong amplitude scintillation as well. Scintillation occurred during the main phase of a modest magnetic storm that, nevertheless, prompted an extreme equatorward movement of the mid‐latitude trough and large background TEC enhancements over the US. Scintillations, however, occurred within TEC and airglow depletions observed over Texas. Finally, scintillation properties including severity and rapidity, and associated TEC signatures are comparable to those associated with equatorial spread F. Plain Language Summary: The ionosphere is a region of the upper atmosphere characterized by a relatively large density of free ions and electrons created, in most part, by solar photoionization. Spatial and temporal variations in the ionospheric electron density cause the diffraction of radio waves such as those used by GPS. The diffraction of the radio waves, as a result, cause fluctuations in the amplitude and/or phase of signal measured by a ground‐based receiver, for instance. These fluctuations are referred to as ionospheric scintillations. Ionospheric scintillations are commonly observed at low and high latitudes, where ionospheric irregularities are known to develop very frequently. Here, we report detailed observations of an ionospheric scintillation event that occurred on June 1st, 2013 over mid‐latitudes (Southern United States) where scintillations are thought to occur very rarely. We were able to capture the event with a specialized scintillation monitor during an educational project. This fortunate observation provided details about the properties (severy, rapidity, frequency scaling, etc.) of the observed mid‐latitude scintillations. The report provides new information about mid‐latitude scintillation that is of interest to a better fundamental understanding of ionospheric irregularities and their impact on signals in the frequency band used by global navigation satellite systems (GPS, Galileo, BeiDou, etc.). Key Points: We present and discuss the detection of L‐Band ionospheric scintillations that occurred over southern United States The severity and temporal properties of the observed scintillations are similar to those of events associated with equatorial plasma bubbles A modest geomagnetic storm prompted extreme background ionospheric conditions and perturbations leading to the observed scintillations