The ionospheric condition and GPS positioning performance during the 2013 tropical cyclone Usagi event in the Hong Kong region

Abstract

The ionosphere plays a critical role in the electromagnetic waves in communication systems such as the global positioning system (GPS). However, it is suspected that the strong convection during the tropical cyclone (TC) events can be a trigger to anomalous electron density variation in the ionosphere. This study analyzed the variation of three ionosphere-related parameters based on the GPS data including scintillation index S4, cycle slips, and total electron content (TEC) rate (TECR) during the tropical cyclone event (the 2013 TC Usagi) in the Hong Kong region. The results showed that the ionosphere-related parameters had a consistent significant increase on the second day after the Usagi made landfall near Hong Kong. Consequently, the positioning performance of GPS precise point positioning (PPP) and relative positioning modes was degraded. The degradation was ~ 138%, ~ 181%, and ~ 460% in the east (root mean square (RMS) 0.050 m), north (RMS 0.045 m), and up (RMS 0.185 m), respectively, compared with the RMS of 0.021 m in the east, 0.016 m in the north, and 0.033 m in the up on the normal day. Regarding the relative positioning, the positioning errors in the east (RMS 0.134 m) and north (RMS 0.118 m) directions were ~ 7.1 and ~ 7.9 times, respectively, as large as the RMS of 0.019 m in the east and 0.015 m in the north on the normal day. The positioning errors in the up (RMS 0.513 m) direction were ~ 12.2 times larger than the RMS of 0.042 m on the normal day.

Evaluating Total Electron Content (TEC) Detrending Techniques in Determining Ionospheric Disturbances during Lightning Events in A Low Latitude Region

“…All days were void of geomagnetic storm or solar condition events. The disturbance storm time (Dst) and solar condition index (F10.7 index) were less than −30 nT [28] and 150 [8], respectively. Figure 2 shows the Dst and F10.7 indices for the set of days.…”

“…Each best fit method produces different results, which may or may not necessarily detect the impact a weather event makes on the signal or adequately show the occurrence of the event. In using GNSS for space weather event studies, extensive studies have been done on geomagnetic storms [2][3][4], earthquakes [5,6], and typhoons [7][8][9]. The fitting methods have been mostly used in these studies to detect travelling ionosphere disturbance (TID) and other ionosphere irregularities.…”

An Investigation of Response of the Tropical Cyclone Ockhi in the Equatorial Ionosphere over the Indian region

“…Also, ionosphere could alter its behavior while cyclone approaching the continent and our results show that TEC anomaly deviates below the normal day on the landfall day is consistent with earlier report (18) noticed the deviation of 5 TECU before landfall and 3 TECU on the day of landfall of a typhoon using network of 50 GPS stations. The ionosphere parameters like foF2, electron concentration, and TEC decreases about a day after landfall of TC (11,31) and for some cases an increase in TEC observed (32) . In addition, decrease in foF2 marked during the onset of cyclone (12) while the same observed for the period of 2200 to 0300 in our study.…”

“…Whereas for cyclone Phailin, energy released during the lightning activity perturbs the ionospheric TEC over the Indian region (34) . For cyclone Usagi, the ionosphere-related parameters had anomalous electron density variation on the second day after landfall near Hong Kong (32) .…”

“…Also, the turbulence leads to transferring the energy influenced from lower atmosphere to ionosphere induced by tropical cyclone (TC) (5,6) . Besides, the gravity waves in the form of convective activity (7) and atmospheric tides generated by tropospheric weather systems (8) impacts on the variation of electron density in the ionosphere by analyzing the Total Electron Content (TEC) (9) . The GWs generated by TC have a time period with range of several minutes to hours depends on the intensity and duration of the event (10) and the waves can propagate in the horizontal direction for the several kilometers (11) .…”