arXiv subjects

Yaqi Jin

Publications and source records attributed to Yaqi Jin.

6 recordsLinked to original sources

arXiv2026

Statistical Models of Ionospheric Variability and Irregularities in the Topside Ionosphere Based on the Swarm Satellite Data

The ionosphere is a highly complex plasma containing electron density structures with a wide range of spatial scales. Coupling of the ionosphere with the Earth's magnetosphere and the solar wind, as well as to the neutral atmosphere, makes the ionosphere highly dynamic and highly dependent on the driving processes. Thus, modelling the ionosphere and capturing its full dynamic range considering all spatiotemporal scales is challenging. Swarm is the European Space Agency's (ESA) first constellation mission for Earth Observation, comprising multiple satellites in low Earth orbit. During the Swarm-VIP-Dynamic project, a suite of statistical models has been developed using observations from Swarm and proxies for heliogeophysical processes. The statistical modelling technique of Generalised Linear Modelling was used to create models for both the electron density and the variability of the plasma structures at horizontal spatial scales between 7.5 km and 100 km. Separate models were created for low, middle, auroral and polar latitudes. The models make predictions based on explanatory variables, which act as proxies for the underlying physical processes. The performance of the models of the electron density approached the theoretical best values for some of the goodness-of-fit statistics. This suggests that the modelling method is appropriate for the task undertaken. The models of ionospheric variability at larger spatial scales (about 100 km) also perform well, however the model performance decreases at smaller spatial scales. This suggests that there are physical processes missing from the models. Possible candidates are instability processes or driving forces of the ionosphere by wave activity from below, neither of which are captured by the models.

physics.space-ph↗

arXiv2026

A quiet STEVE disturbs navigation satellites' signals in the Antarctic

Strong Thermal Emission Velocity Enhancement (STEVE) is a narrow optical phenomenon that occurs equatorward of the auroral oval and is associated with intense subauroral plasma flows and thermospheric heating. Although these conditions can produce plasma irregularities, direct evidence of STEVE effects on radio wave propagation during geomagnetically quiet conditions has so far not been observed. Here we report for the first time a STEVE event observed over Antarctica during quiet geomagnetic conditions and show that it produced measurable fluctuations in the Global Navigation Satellite System (GNSS) signals. Using coordinated optical observations and high-resolution (50 Hz) GNSS scintillation measurements from two Antarctic stations, we identify enhanced phase and amplitude scintillation coincident with intersections between GNSS signal paths and the STEVE arc. The observations indicate the presence of plasma irregularities and suggest substantial temporal variations in the apparent altitude of the optical structure (vertical motion within the 130-270 km range). We find that even a relatively weak STEVE event can affect the GNSS signal propagation in the absence of major geomagnetic disturbances, extending previous studies that associated such effects primarily with storms and intense auroral activity. This finding expands the understanding of STEVE's geophysical impact and highlights potential vulnerabilities in satellite-based navigation systems during seemingly benign space weather conditions. The fact that this STEVE event occurred just off the Antarctic coastline, where scientific expeditions and seagoing vessels rely heavily on precise positioning indicates that STEVE-related plasma structuring should be considered in assessments of the GNSS performance under otherwise quiet geomagnetic conditions in subauroral regions.

physics.space-ph↗

arXiv2026

Multi-Scale Irregularities Product: a data product utilizing the high-resolution Swarm plasma density data for space weather applications

We use the high-resolution Swarm faceplate plasma density data at 16 Hz to develop a set of parameters that can characterize multi-scale ionospheric structures and irregularities along the Swarm orbit. We present the methods for calculating density gradients over different window sizes, rate of change of density index, power spectral density and the spectral slope at both low and high latitudes. The faceplate plasma data are not continuously available through the years. However, about 8 years of data from Swarm A are processed from late 2014 to the end of 2025. Some statistical results from Swarm A are presented. The variations of plasma structures and irregularities are dependent on solar activity, season, local time and geomagnetic activities, and the variations show different patterns between low and high latitudes. For example, the high-latitude ionosphere is characterized by persistent ionospheric structures and irregularities poleward of 60 magnetic latitude, while the low-latitude ionospheric irregularities are only dominant during 19-01 local time near the magnetic equator. The occurrence of steep spectral slope at high latitudes shows clear seasonal variations, i.e., it maximizes during local summer and minimizes during local winter in both hemispheres. However, the occurrence of steep spectral slope at low latitudes is only sensible when significant plasma structures and irregularities are present. We further calculate the histogram of spectral slopes at low latitudes when the rate of change of density index is enhanced. The histogram resembles a Gaussian distribution with an expected value of 1.97. The processed data are available to the wider community. Given the high resolution, this new data product will be useful for the scientific communities that are interested in the magnetosphere-ionosphere-thermosphere coupling and near-Earth space environment.

physics.space-ph↗

arXiv2025

Eastward Transients in the Dayside Ionosphere II: A Parallel-plate Capacitor-Like Effect

During the 23 April 2023 geospace storm, we observed chorus wave-driven, energetic particle precipitation on closed magnetic field lines in the dayside magnetosphere. Simultaneously and in the ionosphere's bottom-side, we observed signatures of impact ionization and strong enhancements in the ionospheric electric field, via radar-detection of meter-scale turbulence, and with matching temporal characteristics as that of the magnetospheric observations. We detailed this in a companion paper. In the present article, we place those observations into context with the dayside ionosphere, and describe a remarkably similar event that took place during the May 2024 geospace superstorm. In both cases, fast, eastward-moving electric field structures were excited equatorward of the ionospheric cusp, on closed magnetic field-lines -- observations that challenge existing modes of explanation for electrodynamics in the cusp-region, where most such observations are interpreted in the context of poleward-moving auroral forms. Instead, primarily eastward-moving electric field structures were associated with turbulent Hall currents that are perhaps characteristically excited during geospace storms by wave-particle interactions near magnetospheric equator or by proton precipitation characteristics in the cusp, forming a `parallel-plate capacitor-like effect'. We propose that transient eastward electrodynamic bursts in the dayside ionosphere might be a common, albeit previously unresolved, feature of geomagnetic storms.

physics.space-ph↗

arXiv2025

Meter-scale Observations of Equatorial Plasma Turbulence

The multi-Needle Langmuir Probe collects an electron current through four fixed-bias cylindrical copper needles. This allows for an extremely high sampling frequency, with plasma properties being inferred through polynomial fitting in the current-voltage plane. We present initial results from such a multi-needle probe mounted on the International Space Station, orbiting Earth at an altitude of around 400 km. That altitude, and its orbital inclination (~50 degrees), place the ISS as a suitable platform for observing equatorial plasma bubbles. In case studies of such turbulent structuring of the F-region plasma, we observe density timeseries that conserve considerable detail at virtually every level of magnification down to its Nyquist scale of 2-5 meters. We present power spectral density estimates of the turbulent structuring found inside equatorial plasma bubbles, and we discuss apparent break-points at scale-sizes between 1 m and 300 m, which we interpret in the light of turbulent dissipation as kilometer-scale swirls produced by the gradient-drift instability dissipate in the plasma.

physics.space-ph↗

arXiv2017

GPS scintillations associated with cusp dynamics and polar cap patches

This paper investigates the relative scintillation level associated with cusp dynamics (including precipitation, flow shears, etc.) with and without the formation of polar cap patches around the cusp inflow region by the EISCAT Svalbard radar (ESR) and two GPS scintillation receivers. A series of polar cap patches were observed by the ESR between 8:40 and 10:20 UT on December 3, 2011. The polar cap patches combined with the auroral dynamics were associated with a significantly higher GPS phase scintillation level (up to 0.6 rad) than those observed for the other two alternatives, i.e., cusp dynamics without polar cap patches, and polar cap patches without cusp aurora. The cusp auroral dynamics without plasma patches were indeed related to GPS phase scintillations at a moderate level (up to 0.3 rad). The polar cap patches away from the active cusp were associated with sporadic and moderate GPS phase scintillations (up to 0.2 rad). The main conclusion is that the worst global navigation satellite system space weather events on the dayside occur when polar cap patches enter the polar cap and are subject to particle precipitation and flow shears, which is analogous to the nightside when polar cap patches exit the polar cap and enter the auroral oval.

physics.space-ph↗