The coronal electron density distribution determined from dual-frequency ranging measurements during the 1991 solar conjunction of the ULYSSES spacecraft

Bird, M. K.; Volland, H.; Paëtzold, M.; Edenhofer, P.; Asmar, S. W.; Brenkle, J. P.

doi:10.1086/174073

Cited by 76 publications

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“…The model of Bird et al (1994) is especially useful since it results from radio propagation observations that, like the primary measurements used in this paper, involve a path integration along the line of sight. For each of these expressions, we can calculate an estimate of the plasma density at the impact parameter n 0 .…”

Section: Models For the Solar Wind Plasma Densitymentioning

confidence: 99%

The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind

Spangler

2002

ApJ

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Recent radio wave interplanetary scintillation observations have improved our knowledge of the level of turbulent fluctuations of plasma density in the inner solar wind at heliocentric distances of 16-26 R and less accurately outside this range. This information relates to fluctuations in the inertial subrange of the turbulence. Of particular concern in this paper is the heliocentric distance dependence of the power-law normalization parameter C 2 N . This measurement of C 2 N , when combined with independent measurements of the mean plasma density in the inner solar wind, indicates that the dimensionless amplitude of the turbulence n =n n is low, of the order of 6%-15%, where n is the standard deviation of the density fluctuations and n n is the mean value. The deduced value for depends on an assumed value for the outer scale of the turbulence, l o . I adopt a fiducial value of l o ¼ 1 R . A comparison is made with independent estimates of , from both radio remote sensing in the same part of space and in situ measurements at greater distances. Satisfactory agreement occurs. I discuss the possibility that this dimensionless density amplitude might be a proxy for the corresponding amplitude of the magnetic field fluctuations. This is a controversial assertion. However, if it is the case, the measurements suggest that the turbulence in the inner solar wind is weak, in the sense of being dynamically and thermodynamically important.

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Section: Models For the Solar Wind Plasma Densitymentioning

confidence: 99%

The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind

Spangler

2002

ApJ

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“…It was found that the resulting estimates of fluctuation in electron number density lay within about 1% of the total electron number density expected at the different solar impact distances using a modified Allan-Baumbach formula [Bird et al, 1994] for the quiet background. For example, at 4 R S impact distance, the estimated fluctuation in electron number density runs $300/cm 3 .…”

Section: Phase Scintillationmentioning

confidence: 69%

Spectral broadening and phase scintillation measurements using interplanetary spacecraft radio links during the peak of solar cycle 23

Morabito

2009

Radio Science

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[1] When an interplanetary spacecraft is in a solar superior conjunction configuration, the received radio signals are degraded by several effects that generally increase in magnitude as the angle between the spacecraft and the Sun (Sun-Earth-Probe or SEP angle) decreases as viewed by a terrestrial tracking station. During periods of quiescent solar activity, phase scintillation and spectral broadening follow well-defined trends as a function of solar impact distance (SEP angle) and link frequency. During active solar periods, the magnitudes of these effects increase above background levels predicted by the quiet period models. Several such events were observed during the solar superior conjunction of the Cassini spacecraft during the peak of solar cycle 23 in May 2000. Pronounced features in the spectral broadening data above the quiet background appear to be associated with Coronal Mass Ejections (CMEs), and last for extended periods of time ranging from $30 min to $4 h. These features are coincident with periods of increased activity seen in the region of the spacecraft signal source on coronal white light images, and tend to be related or matched with EIT flare events and possibly long-duration flare events seen in satellite X-ray data. Several such features were captured in the May 2000 Cassini solar conjunction phase scintillation and spectral broadening data at X band (8.4 GHz) and Ka band (32 GHz) radio frequencies, and are presented here. Such characterizations are beneficial in understanding the impact of such events in future interplanetary communication scenarios during solar conjunction periods.

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“…20-29 R x ). sured electron content during C1 (Bird et al, 1994) to the solar minimum electron content used by Tyler et al (1977). These ratios, as well as the actual values for DL, and N T , are also presented in Table 1.…”

Section: Cross-correlation Analysis and Velocity Estimatesmentioning

confidence: 97%

“…Tyler et al (1977). b Ulysses measurements (Bird et al, 1994). c Adjusted value for solar maximum conditions at C1 (see text).…”

Section: Cross-correlation Analysis and Velocity Estimatesmentioning

confidence: 99%

Solar wind velocity measurements near the sun using Ulysses radio amplitude correlations at two frequencies

Ефимов

Bird

Rudash

et al. 2005

Advances in Space Research

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The coronal electron density distribution determined from dual-frequency ranging measurements during the 1991 solar conjunction of the ULYSSES spacecraft

Cited by 76 publications

References 0 publications

The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind

The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind

Spectral broadening and phase scintillation measurements using interplanetary spacecraft radio links during the peak of solar cycle 23

Solar wind velocity measurements near the sun using Ulysses radio amplitude correlations at two frequencies

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