Low‐Latitude Ionospheric Density Irregularities and Associated Scintillations Investigated by Combining COSMIC RO and Ground‐Based Global Positioning System Observations Over a Solar Active Period

Abstract

This study for the first time presents a locally integrated analysis of occurrences of ionospheric E and F region irregularities/scintillations in southeast China, by employing radio occultation (RO) profile data retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites and observations from a ground-based Global Navigation Satellite System receiver over a solar active period from 2014 to 2015. Their occurrences in both nighttime and daytime were examined by using both amplitude scintillation index (S 4 ) and the rate of change of total electron content index. It is found that (1) F region irregularities occurred predominantly during 20-03 local time (LT) and exhibited maximum (minimum) during equinoxes (solstices) and equinoctial (solstice) asymmetry. Their geographic mapping reveals the maximum occurrence in the westward tilted structure of equatorial plasma bubbles. In addition, the altitude-time variations indicate that their occurrences at higher altitudes were prevailing at 20-22 LT. (2) The E region irregularities were found prominently during 15-00 LT at altitudes of 90-110 km with an even geographic distribution. Their occurrences with maximum in summer (May-August) were distinctly detected by RO observations but insignificantly by ground-based observations. (3) By examining simultaneous observations of E and F region irregularities, it is found that they appeared absent during 21-00 LT and predominant after midnight. This could be related to the weakening/disruption of sporadic E (Es) layers during the development of equatorial plasma bubbles. A sign of coupling of E and F regions during nighttime is likely revealed from RO profile data. . Low-latitude ionospheric density irregularities and associated scintillations investigated by combining COSMIC RO and groundbased Global Positioning System observations over a solar active period.

Global View of Ionospheric Disturbance Impacts on Kinematic GPS Positioning Solutions During the 2015 St. Patrick's Day Storm

“…In the present study, we use the ROTI metric derived from GPS dual-frequency carrier phase measurements to characterize ionospheric irregularity occurrences. Defined as the standard deviation of the rate of TEC, the ROTI is an indicator generally used for quantifying small-scale ionospheric plasma irregularities (e.g., Cherniak et al, 2014Cherniak et al, , 2018Pi et al, 1997;Yang & Liu, 2018). Because small-scale plasma irregularities are expected to generate significant scintillation effects on GPS signals, we use the ROTI to characterize severe ionospheric plasma density irregularities and their impacts on kinematic PPP solutions throughout our analysis.…”

Climatology Characteristics of Ionospheric Irregularities Described with GNSS ROTI

“…Another data product describing phase fluctuation activity using GNSS ROTI measurements is being developed, and since 2018 it has been freely accessible as an International GNSS Service (IGS) ROTI map product [18,19]. For many years, ROTI has been successfully utilized for ionospheric irregularity studies at sub-auroral [3,[20][21][22] and equatorial [23][24][25][26][27] latitudes. Most often, a detailed ROTI analysis is performed for particular events or case-studies, such as severe geomagnetic storms.…”

Assessing the Kinematic GPS Positioning Performance Under the Effect of Strong Ionospheric Disturbance Over China and Adjacent Areas During the Magnetic Storm

“…The rate of change of TEC index (ROTI) is derived from the rate of change of total electron content (ROT) were used to represent ionospheric irregularities shown as Equations and , where $$< \hspace*{.5em} > $$ represents making average treatment, i is a GPS satellite and t k is an epoch time. The ROTI is an indicator generally used for quantifying small‐scale ionospheric plasma irregularities (e.g., Cherniak et al., 2015; Pi et al., 1997; Yang & Liu, 2018). Because small‐scale plasma irregularities are expected to generate significant scintillation effects on GPS signals, we use the ROTI to characterize severe ionospheric plasma density irregularities and their impacts on kinematic PPP solutions throughout our analysis.…”