Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites

Park, J.; Lühr, Hermann; Stolle, Claudia; Malhotra, Garima; Baker, J. B.; Buchert, Stephan; Gill, Reine

doi:10.5194/angeo-33-829-2015

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…Another possible application is to derive along‐track plasma convection speed V from cross‐correlating magnetic field structures on Swarm A and Swarm C. Assuming that plasma structures remain static during the time it takes for the two satellites to cross them, the plasma motion can be derived by comparing the observed delay Δ τ , found from cross correlation, to the actual time lag between the two satellites Δ t :

V = \frac{normalΔ τ - normalΔ t}{normalΔ τ} v_{s},

where v s is the speed of the satellites and V is positive when the convection is in the same direction as the satellites. Park et al () demonstrated this principle using Swarm density measurements from the first few months of the mission, when all three satellites were in a pearl‐on‐a‐string configuration with Δ t between 1 and 3 min. They noted that with Δ t ≈5 s, which is the case in the current constellation, the 2‐Hz sampling rate of plasma density is too low to give precise estimates of the convection.…”

Section: Discussionmentioning

confidence: 99%

“…where v s is the speed of the satellites and V is positive when the convection is in the same direction as the satellites. Park et al (2015) demonstrated this principle using Swarm density measurements from the first few months of the mission, when all three satellites were in a pearl-on-a-string configuration with Δt between 1 and 3 min. They noted that with Δt ≈ 5 s, which is the case in the current constellation, the 2-Hz sampling rate of plasma density is too low to give precise estimates of the convection.…”

Section: Potential Applicationsmentioning

confidence: 99%

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Magnetic Effects of Plasma Pressure Gradients in the Upper F Region

Laundal

Hatch

Moretto

2019

Geophysical Research Letters

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The Swarm satellites fly at altitudes that at polar latitudes are generally assumed to only contain currents that are aligned with the local magnetic field. Therefore, disturbances along the main field direction are mainly signatures of auroral electrojet currents, with a relatively smooth structure due to the distance from the currents. Here we show that superimposed on this smooth signal is an irregular pattern of small perturbations, which are anticorrelated with the plasma density measured by the Langmuir probe. We show that the perturbations can be remarkably well reproduced by assuming they represent a j × B force, which balances the plasma pressure gradient implied by the density variations. The associated diamagnetic current, previously reported to be most important near the equator, appears to be a ubiquitous phenomenon also at polar latitudes. A spectral analysis indicates that this effect dominates magnetic field intensity variations at small‐scale sizes of a few tens of kilometers.

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V = \frac{normalΔ τ - normalΔ t}{normalΔ τ} v_{s},

Section: Discussionmentioning

confidence: 99%

Section: Potential Applicationsmentioning

confidence: 99%

Magnetic Effects of Plasma Pressure Gradients in the Upper F Region

Laundal

Hatch

Moretto

2019

Geophysical Research Letters

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“…Plasma motion in the high-latitude ionosphere provides important information about magnetosphere-ionosphere-thermosphere coupling. Park et al (2015b) estimated the along-track component of plasma convection within and around the polar cap, using electron density profiles measured by the three Swarm satellites. In both hemispheres the estimated velocity was generally anti-sunward and in qualitative agreement with Super Dual Auroral Radar Network (SuperDARN) data.…”

Section: Solar Solar Wind and Magnetospheric Drivers Of Variabilitymentioning

confidence: 99%

Variability of Ionospheric Plasma: Results from the ESA Swarm Mission

et al. 2022

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Swarm is the first European Space Agency (ESA) constellation mission for Earth Observation. Three identical Swarm satellites were launched into near-polar orbits on 22 November 2013. Each satellite hosts a range of instruments, including a Langmuir probe, GPS receivers, and magnetometers, from which the ionospheric plasma can be sampled and current systems inferred. In March 2018, the CASSIOPE/e-POP mission was formally integrated into the Swarm mission through ESA’s Earthnet Third Party Mission Programme. Collectively the instruments on the Swarm satellites enable detailed studies of ionospheric plasma, together with the variability of this plasma in space and in time. This allows the driving processes to be determined and understood. The purpose of this paper is to review ionospheric results from the first seven years of the Swarm mission and to discuss scientific challenges for future work in this field.

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“…In addition, the analysis presented here is sensitive to the assumed polar cap convection velocity. In future investigations of plasma structure lifetimes, special care should be taken in treating plasma convection velocity, for example, by using methods of observing plasma drift velocity (Park et al, 2015).…”

Section: Chemical Recombination Ofmentioning

confidence: 99%

The Lifetimes of Plasma Structures at High Latitudes

Ivarsen

Jin

Spicher

et al. 2021

Preprint

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In the high-latitude ionosphere, the primary source regions for plasma structuring tend to be located in the dayside cusp and the nightside auroral oval, where electron precipitation is abundant (Kelley et al., 1982). The large-scale polar convection pattern then causes the structured plasma to travel anti-sunward through the polar cap (Cowley & Lockwood, 1992;Dungey, 1961). In fact, the transport of irregularities from particle precipitation-driven source regions into the polar cap proper is an essential reason for the observed polar cap plasma structures (Cowley, 2000), although alternative sources of structuring inside the polar cap proper exist, such as the gradient drift instability mechanism (e.g., Tsunoda, 1988). Without an irregularity production source, the lifetime of a given plasma structure entering the polar cap is an indicator of the effectiveness with which the plasma structures are diffusing into the surrounding plasma. Indeed, Jin et al. (2017) found that occurrence of plasma irregularities drops significantly when plasma leaves the cusp region.The occurrence of plasma irregularities in the high-latitude regions is in general subject to strong seasonal dependencies (

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Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites

Cited by 5 publications

References 15 publications

Magnetic Effects of Plasma Pressure Gradients in the Upper F Region

Magnetic Effects of Plasma Pressure Gradients in the Upper F Region

Variability of Ionospheric Plasma: Results from the ESA Swarm Mission

The Lifetimes of Plasma Structures at High Latitudes

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