Global Positioning System (GPS) Scintillation Associated with a Polar Cap Patch

A Global Positioning System (GPS) network in the polar cap, along with ionosonde and SuperDARN radar measurements, are used to study GPS signal amplitude and phase scintillation associated with a polar cap patch. The patch was formed due to a north-to-south transition of the interplanetary magnetic field (IMF Bz). The patch moved antisunward with an average speed of ~600 m/s and lasted for ~2 h. Significant scintillation occurred on the leading edge of the patch, with smaller bursts of scintillation inside and on the trailing edge. As the patch moved, it maintained the integrity of the scintillation, producing irregularities (Fresnel scale) on the leading edge. There were no convection shears or changes in the direction of convection during scintillation events. Observations suggest that scintillation-producing Fresnel scale structures are generated through the non-linear evolution of the gradient drift instability mechanism.

Characteristics of Ionospheric Scintillation in Chengdu, China

When wireless electromagnetic waves pass through the earth's atmosphere, they are affected by ionospheric irregularities, and their amplitude and phase will jitter rapidly in a short period of time, which is called ionospheric scintillation. With the human exploration of outer space and the demand for space communication, the study of ionospheric scintillation characteristics and its influence on electromagnetic communication has become increasingly important. This paper used the observation data received by GPS scintillation/TEC receivers in the Chengdu (104.07° N, 30.67° E) area of China from January 2018 to September 2020, and a data processing program was developed for the received GPS/BDS/GAL. The satellite data at multiple frequency points were processed to extract key data such as S4, azimuth angle, and elevation angle, and then the annual changes in ionospheric scintillation in the Chengdu region and the characteristics of local time changes were statistically analysed. The results show that the frequency and intensity of ionospheric scintillation events have obvious half-year changes. The scintillation intensity and frequency in spring and autumn are higher and more frequent than those in summer and winter; and scintillation events mainly occur at night. but they also occur during the day, mostly in the afternoon; and their occurrence is related to the airspace and is further closely related to the elevation and azimuth angles of the observation point. The overall scintillation events from 2018 to 2020 were in a gradual downward trend. At the end of May 2018, a scintillation event with a longer duration occurred. Further analysis showed that the occurrence of scintillation events increased with the rapid changes in solar activity and the geomagnetic environment. There is a certain positive correlation between the changes.

Impact of the substorms and polar cap patches on GPS radio waves at polar latitudes.

The comparative research of the influence of substrorm precipitation and polar cap patches (PCP) on the GPS signals disturbances in the polar ionosphere was done. For this aim we use the GPS scintillation receivers at Ny-Ålesund, operated by the University of Oslo. The presence of the auroral particle precipitation and polar cap patches was determined by using data from the EISCAT 42m radar on Svalbard. We consider tens of events when the simultaneous EISCAT 42m and GPS data were available. We demonstrate that substorm-associated precipitations can lead to a strong GPS phase (σΦ) scintillations up to ~2 radians which is much stronger than those usually produced by PCPs. At the same PCPs can lead to strong ROT (rate of total electron content) variations. So our observations suggest that the substorms and PCPs, being different types of the high-latitude disturbances, lead to the development of different types and scales of ionospheric irregularities.

Recent achievements from the Swarm mission on the low latitude space environment and combinations with other satellite missions

<p>The Swarm three-satellite constellation mission provides high resolution and high-quality observations of the Earth’s magnetic field and of multiple parameters of the ionosphere, which lead to new knowledge on the Earth’s interior and space environment and help to investigate space weather effects on space technology. Several findings would otherwise not have been possible and demonstrate that missions like Swarm are indispensable for Earth and space exploration. In addition, aspects of longterm variations or enhanced understanding in temporal and spatial resolution on regional scales could be gained in combination with other missions. This presentation  focuses on recent achievements on the low latitude ionosphere. Examples include an empirical model of the occurrence of post-sunset equatorial plasma irregularities derived in combination with ten years of CHAMP geomagnetic data, an enhanced description of the Swarm irregularity observations together with regional maps of the South Atlantic ionosphere from GOLD, and the identification of differing GPS scintillation characteristics evoked by the irregularities in comparison with the lower orbit GOCE data. Equatorial electrojet and plasma data from Swarm also helped to empirically prove that Antarctic sudden stratospheric warming events, such as in September 2019, couple to the low latitude ionosphere through modified planetary waves.</p>

Solar cycle and seasonal variations of the GPS phase scintillation at high latitudes

We present the long-term statistics of the GPS phase scintillation in the polar region (70°–82° magnetic latitude) by using the GPS scintillation data from Ny-Ålesund for the period 2010–2017. Ny-Ålesund is ideally located to observe GPS scintillations modulated by the ionosphere cusp dynamics. The results show clear solar cycle and seasonal variations, with the GPS scintillation occurrence rate being much higher during solar maximum than during solar minimum. The seasonal variations show that scintillation occurrence rate is low during summer and high during winter. The highest scintillation occurrence rate is around magnetic noon except for December 2014 (solar maximum) when the nightside scintillation occurrence rate exceeds the dayside one. In summer, the dayside scintillation region is weak and there is a lack of scintillations in the nightside polar cap. The most intriguing features of the seasonal variations are local minima in the scintillation occurrence rate around winter solstices. They correspond to local minima in the F2 peak electron density. The dayside scintillation region migrates equatorward from summer to winter and retreats poleward from winter to summer repetitively in a magnetic latitude range of 74°–80°. This latitudinal movement is likely due to the motion of the cusp location due to the tilt of the Earth’s magnetic field and the impact of the sunlight.