Advances in magnetospheric radio wave analysis and tomography

Cummer, Steven A.; Green, J.L.; Reinisch, B. W.; Fung, S. F.; Kaiser, M. L.; Pickett, J. S.; Christopher, I. W.; Mutel, R. L.; Gurnett, D. A.; Escoubet, C. P.

doi:10.1016/s0273-1177(03)90271-7

Cited by 11 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A key reason for including WBD experiments on all Cluster spacecraft is to allow the location of remote sources to be determined by interferometry. An experiment to test this capability is described by Cummer et al (2003). Rather than a natural radio wave source, the Radio Plasma Imager (RPI) experiment on the Image spacecraft is used as a transmitter.…”

Section: The Cluster Spacecraft and Wideband Data Experimentsmentioning

confidence: 99%

A Review of Cluster Wideband Data Multi‐Spacecraft Observations of Auroral Kilometric Radiation

Yearby

Pickett

2022

JGR Space Physics

View full text Add to dashboard Cite

We review important advances in the understanding of auroral kilometric radiation (AKR) resulting from observations by the Wideband Data instruments on the four Cluster spacecraft. AKR is an intense radio emission originating in the Earth's auroral regions with frequencies typically in the range 50–700 kHz, usually observed from space. It is now widely accepted that AKR is generated by the cyclotron maser instability (CMI) in density cavities in the auroral acceleration region. Multi‐point observations by the Cluster spacecraft with a time delay of arrival technique have allowed the source locations of many individual AKR bursts to be determined. The position uncertainty is around 500 km at the source region or about 200 km when mapped on to the auroral zone. AKR is emitted in a narrow beam close to the tangent to the magnetic field vector in the source region. This has important implications for the possible generation mechanisms, being incompatible with filled or hollow cone beaming models. It also implies that an observer at a given location can only see AKR from a fraction of possibly active source regions. The complex frequency time structure of AKR sometimes shows regular striations or pulsations. Cluster observations of these phenomena have been interpreted as modulation of the CMI by disturbances propagating through the generation region. Exceptionally, AKR can sometimes be observed from low altitude spacecraft or even on the ground. Recent work has involved simultaneous observations of AKR on the Cluster spacecraft and on the ground at the South Pole.

show abstract

Section: The Cluster Spacecraft and Wideband Data Experimentsmentioning

confidence: 99%

A Review of Cluster Wideband Data Multi‐Spacecraft Observations of Auroral Kilometric Radiation

Yearby

Pickett

2022

JGR Space Physics

View full text Add to dashboard Cite

show abstract

“…It is also noted that the statistical electron density model [ Nsumei et al , 2008] was established at a solar maximum, which is when our radio transmission for the tomographic imaging experiment was performed, a different electron density model may be needed if the above method is used again with a two‐satellite radio transmission at different solar cycles or under non‐quiet geomagnetic conditions. With the successful CLUSTER multispacecraft and dual‐frequency radio transmissions for tomographic imaging of the magnetosphere [ Cummer et al , 2003], we hope to eliminate this limitation in future work. For non‐quiet geomagnetic conditions, the direct reconstruction technique developed in our previous study [ Zhai and Cummer , 2005, 2006] should be used with Faraday rotation measurements from multisatellites, dual‐frequency radio transmission for better performance.…”

Section: Magnetospheric Tomographic Imagingmentioning

confidence: 99%

Magnetospheric radio tomographic imaging with IMAGE and Wind

Zhai

Cummer

Green³

et al. 2011

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Recent theoretical studies have shown the feasibility and potential scientific value of radio tomographic imaging of Earth's magnetosphere by measuring Faraday rotation and phase difference (or group delay) of coherent radio wave signals. On 15 August 2000, a 6 W linearly polarized 828 kHz signal transmitted by the Radio Plasma Imager (RPI) on the IMAGE spacecraft was clearly detected by WAVES X and Z antennas on Wind spacecraft. Following our previous analysis of the path-integrated product change of the magnetic field and plasma density based on the spin rate measurement, we report here Faraday rotation measured from absolute antenna orientation using the phase difference between the spin-phase modeled RPI signal and the WAVES X-and Z-antenna received RPI signals. The new approach gives Faraday rotation without the mod (p) ambiguity. The average electron density extracted along a typical signal propagation path over a 1 hour measurement window agrees well with empirical models of the northern polar region derived from years of measurements. Finally, we demonstrate preliminary 2-D radio tomographic imaging of magnetospheric plasma density using the Faraday rotation measurement.

show abstract

“…More recently, Cummer et al, 2003 have successful conducted multi-frequency tests with IMAGE/RPI transmitting and Wind/Waves and all four Cluster/Wideband instruments receiving. Each of these experiments clearly show the Faraday rotation of the electric field at each of the frequencies used.…”

Section: Rpi Transmissions and Reception From Wind And Clustermentioning

confidence: 99%

An Overview of Results From rpi on Image

Green

Reinisch

2003

Space Science Reviews

Self Cite

View full text Add to dashboard Cite

The Radio Plasma Imager (RPI) on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft was designed as a long-range magnetospheric radio sounder, relaxation sounder, and a passive plasma wave instrument. The RPI is a highly flexible instrument that can be programmed to perform these types of measurements at times when IMAGE is located in key regions of the magnetosphere. RPI is the first radio sounder ever flown to large radial distances into the magnetosphere. The long-range sounder echoes from RPI allow remote sensing of a variety of plasmas structures and boundaries in the magnetosphere. A profile inversion technique for RPI echo traces has been developed and provides a method for determining the density distribution of the plasma from either direct or field-aligned echoes. This technique has enabled the determination of the evolving density structure of the polar cap and the plasmasphere under a variety of geomagnetic conditions. New results from RPI show that the plasmasphere refills in slightly greater than a day at L values of 2.8 and that ion heating is probably playing a major role in the overall density distribution along the field-line. In addition, RPI's plasma resonance observations at large radial distances over the polar cap provided in situ measurements of the plasma density with an accuracy of a few percent. For the first time in the magnetosphere, RPI has also observed the plasma D resonances. RPI's long antennas and its very low noise receivers provide excellent observations in the passive receive-only mode when the instrument measures the thermal plasma noise as well as natural emissions such as the continuum radiation and auroral kilometric radiation (AKR). Recent passive measurements from RPI have been compared extensively with images from the Extreme Ultraviolet (EUV) imager on IMAGE resulting in a number of new discoveries. For instance, these combined observations show that kilometric continuum can be generated at the plasmapause from sources in or very near the magnetic equator, within a bite-out region of the plasmasphere. The process by which plasmaspheric bite-out structures are produced is not completely understood at this time. Finally, RPI has been used to successfully test the feasibility of magnetospheric tomography. During perigee passages of the Wind spacecraft, RPI radio transmissions at one and two frequencies have been observed by the Waves instrument. The received electric field vector was observed to rotate with time due to the changing density of plasma, and thus Faraday rotation was measured. Many future multi-spacecraft missions propose to use Faraday rotation to obtain global density pictures of the magnetosphere.

show abstract

Advances in magnetospheric radio wave analysis and tomography

Cited by 11 publications

References 11 publications

A Review of Cluster Wideband Data Multi‐Spacecraft Observations of Auroral Kilometric Radiation

A Review of Cluster Wideband Data Multi‐Spacecraft Observations of Auroral Kilometric Radiation

Magnetospheric radio tomographic imaging with IMAGE and Wind

An Overview of Results From rpi on Image

Contact Info

Product

Resources

About