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norskBlar i forfatter "Spicher, Andres"
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2022 Tonga Volcanic Eruption Induced Global Propagation of Ionospheric Disturbances via Lamb Waves
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-23)The Tonga volcano eruption at 04:14:45 UT on 2022-01-15 released enormous amounts of energy into the atmosphere, triggering very significant geophysical variations not only in the immediate proximity of the epicenter but also globally across the whole atmosphere. This study provides a global picture of ionospheric disturbances over an extended period for at least 4 days. We find traveling ionospheric ... -
The Distribution of Small-Scale Irregularities in the E-Region, and Its Tendency to Match the Spectrum of Field-Aligned Current Structures in the F-Region
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-16)We associate new data from icebear, a coherent scatter radar located in Saskatchewan, Canada, with scale-dependent physics in the ionosphere. We subject the large-scale icebear 3D echo patterns (treated as 2D point clouds) to a data analysis technique hitherto never applied to the ionosphere, a technique that is widely applied in cosmological red-shift surveys to characterize the spatial clustering ... -
Electron-neutral collisions effects on Langmuir probe in the lower E-region ionosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-21)We present the first set of particle-in-cell simulations including Monte Carlo collisions between charged and neutral particles used to simulate a cylindrical Langmuir probe in the electron saturation regime with a collisional electron sheath. We use a setup focused on the E-region ionosphere; however, the results of these simulations are analyzed in a general sense using dimensionless values. We ... -
GNSS Scintillations in the Cusp, and the Role of Precipitating Particle Energy Fluxes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-16)Using a large data set of ground-based GNSS scintillation observations coupled with in situ particle detector data, we perform a statistical analysis of both the input energy flux from precipitating particles, and the observed occurrence of density irregularities in the northern hemisphere cusp. By examining trends in the two data sets relating to geomagnetic activity, we conclude that observations ... -
Interferometric Study of Ionospheric Plasma Irregularities in Regions of Phase Scintillations and HF Backscatter
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-08)We investigate the nature of small-scale irregularities observed in the cusp by the Twin Rockets to Investigate Cusp Electrodynamics-2 (TRICE-2) in regions of enhanced phase scintillations and high-frequency coherent radar backscatter. We take advantage of the fact that the irregularities were detected by spatially separated probes, and present an interferometric analysis of both the observed electron ... -
Investigating Spatial and Temporal Structuring of E-Region Coherent Scattering Regions Over Northern Norway
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-26)Recently, it has been shown that the Spread Spectrum Interferometric Multistatic meteor radar Observing Network radar system located in northern Norway is capable of measuring ionospheric E-region coherent scatter with spatial and temporal resolutions on the order of 1.5 km and 2 s, respectively. Four different events from June and July of 2022 are examined in the present study, where the coherent ... -
Ionospheric Flow Vortex Induced by the Sudden Decrease in the Solar Wind Dynamic Pressure
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)Abrupt changes in the solar wind dynamic pressure can greatly affect the Earth's magnetosphere-ionosphere system. We present an ionospheric flow vortex in the morning sector during the sudden decrease in the solar wind dynamic pressure. The flow vortex was clearly observed by both the Hankasalmi radar and the azimuthal scan mode of the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR). The ... -
Measuring small-scale plasma irregularities in the high-latitude E- and F-regions simultaneously
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-18)The ionosphere, Earth’s space environment, exhibits widespread turbulent structuring, or plasma irregularities, visualized by the auroral displays seen in Earth’s polar regions. Such plasma irregularities have been studied for decades, but plasma turbulence remains an elusive phenomenon. We combine scale-dependent measurements from a ground-based radar with satellite observations to characterize ... -
Multi-scale measurements of mesospheric aerosols and electrons during the MAXIDUSTY campaign
(Journal article; Peer reviewed, 2019-04-08)We present in situ measurements of small-scale fluctuations in aerosol populations as recorded through a mesospheric cloud system from the Faraday cups DUSTY and MUDD during on the MAXIDUSTY-1 and 1B sounding rocket payloads launched in the summer of 2016. <br>Two mechanically identical DUSTY probes mounted with an inter-spacing of ∼10 cm recorded very different currents, with strong spin modulation, ... -
On the strength of E and F region irregularities for GNSS scintillation in the dayside polar ionosphere
(Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-02)We present results of the study conducted to quantify the relative contribution of different ionospheric regions to phase scintillation in Global Navigation Satellite Systems (GNSS) at the dayside high latitude ionosphere. By taking advantage of the scanning capability of the 32-m EISCAT radar in Svalbard (ESR) and its recurrent favourable location below the dayside auroral region, we developed ... -
Pronounced Suppression and X-Pattern Merging of Equatorial Ionization Anomalies After the 2022 Tonga Volcano Eruption
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-27)Following the 2022 Tonga Volcano eruption, dramatic suppression and deformation of the equatorial ionization anomaly (EIA) crests occurred in the American sector ∼14,000 km away from the epicenter. The EIA crests variations and associated ionosphere-thermosphere disturbances were investigated using Global Navigation Satellite System total electron content data, Global-scale Observations of the ... -
The role of particle precipitation on plasma structuring at different altitudes by in-situ measurements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-02)The plasma in the cusp ionosphere is subject to particle precipitation, which is important for the development of large-scale irregularities in the plasma density. These irregularities can be broken down into smaller scales which have been linked to strong scintillations in the Global Navigation Satellite System (GNSS) signals. We present power spectra for the plasma density irregularities in the ... -
Significant ionospheric hole and equatorial plasma bubbles after the 2022 Tonga volcano eruption
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-28)This paper investigates the local and global ionospheric responses to the 2022 Tonga volcano eruption, using ground-based Global Navigation Satellite System total electron content (TEC), Swarm in situ plasma density measurements, the Ionospheric Connection Explorer (ICON) Ion Velocity Meter (IVM) data, and ionosonde measurements. The main results are as follows: (a) A significant local ionospheric ... -
Simultaneous Global Ionospheric Disturbances Associated With Penetration Electric Fields During Intense and Minor Solar and Geomagnetic Disturbances
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)A new observational phenomenon, named Simultaneous Global Ionospheric Density Disturbance (SGD), is identified in GNSS total electron content (TEC) data during periods of three typical geospace disturbances: a Coronal Mass Ejection-driven severe disturbance event, a high-speed stream event, and a minor disturbance day with a maximum Kp of 4. SGDs occur frequently on dayside and dawn sectors, with ... -
Space and atmospheric physics on Svalbard: a case for continued incoherent scatter radar measurements under the cusp and in the polar cap boundary region
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-04)Incoherent scatter radars (ISRs) represent the only instrument (both ground and space based) capable of making high temporal and spatial resolution measurements of multiple atmospheric parameters—such as densities, temperatures, particle velocities, mass flux—over an altitude range covering the entire mesosphere/lower thermosphere/ionosphere (MLTI) system on a quasi-continuous basis. The EISCAT ... -
Statistical Distribution of Decameter Scale (50 m) Ionospheric Irregularities at High Latitudes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-15)We present a study of decameter scale ionospheric irregularities using in-situ electron density data from the NorSat-1 satellite. During the current period of low solar activity, NorSat-1 frequently observes significant plasma irregularities from several 10 s km down to several decameter. These are often observed near the dayside cusp and dawnside auroral zone. The decameter-scale irregularities are ... -
Steepening Plasma Density Spectra in the Ionosphere: The Crucial Role Played by a Strong E-Region
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-28)Based on the Swarm 16 Hz Advanced Plasma Density data set, and using the Swarm A satellite, we apply automatic detection of spectral breaks in seven million sampled plasma density power spectra in the high-latitude F-region ionosphere. This way, we survey the presence of plasma irregularity dissipation due to an enhanced E-region conductance, caused both by solar photoionization and particle ... -
Suppression of ionospheric irregularity due to auroral particle impact
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-16)The VISIONS-2 35.039 sounding rocket was launched from Ny-Ålesund, Svalbard, on 7 December 2018 at 11:06 UT, and traveled overhead of the cusp aurora. The payload reached an apogee of 806.6 km and provided measurements of the electric field (E) and electron density (N<sub>e</sub> ) with a high sampling rate of 6,250 Hz. The high-sampling-data make it possible to estimate the horizontal structure ... -
A technique for volumetric incoherent scatter radar analysis
(Journal article; Tidsskriftartikkel, 2023-01-19)Volumetric measurements of the ionosphere are important for investigating spatial variations of ionospheric features, like auroral arcs and energy deposition in the ionosphere. In addition, such measurements make it possible to distinguish between variations in space and time. While spatial variations in scalar quantities such as electron density or temperature have been investigated with incoherent ... -
Turbulence and Intermittency in the Winter Cusp Ionosphere Studied With the ICI Sounding Rockets
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-15)The characteristics of turbulent plasma in the winter cusp ionosphere is studied based on in-situ data from the Investigation of Cusp Irregularities (ICI) sounding rockets. The electron density fluctuations from ICI-2 and ICI-3 missions have been analyzed for the whole flight, using advanced timeseries analysis techniques. The analysis of the autocorrelation scale is indicative of the turbulence ...
