Solar cycle evolution of solar wind speed structure between 1973 and 1985 observed with the interplanetary scintillation method

Kojima, M.; Kakinuma, Takakiyo

doi:10.1029/ja092ia07p07269

Cited by 132 publications

(64 citation statements)

References 28 publications

(15 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, Kojima & Kakinuma (1987), Kojima et al (1998), Breen et al (2000), and Tokumaru et al (2010) have made maps of outflow speeds on a source surface by interpreting the scintillation pattern from distant radio sources such as quasars. The scintillations carry information about the speeds of small scale structures moving away from the Sun in the solar wind.…”

Section: Introductionmentioning

confidence: 99%

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM

Strachan¹,

Panasyuk²,

Kohl³

et al. 2011

ApJ

View full text Add to dashboard Cite

We analyze data from the Solar and Heliospheric Observatory to produce global maps of coronal outflow velocities and densities in the regions where the solar wind is undergoing acceleration. The maps use UV and white light coronal data obtained from the Ultraviolet Coronagraph Spectrometer and the Large Angle Spectroscopic Coronagraph, respectively, and a Doppler dimming analysis to determine the mean outflow velocities. The outflow velocities are defined on a sphere at 2.3 R from Sun-center and are organized by Carrington Rotations during the solar minimum period at the start of solar cycle 23. We use the outflow velocity and density maps to show that while the solar minimum corona is relatively stable during its early stages, the shrinkage of the north polar hole in the later stages leads to changes in both the global areal expansion of the coronal hole and the derived internal flux tube expansion factors of the solar wind. The polar hole areal expansion factor and the flux tube expansion factors (between the coronal base and 2.3 R ) start out as super-radial but then they become more nearly radial as the corona progresses away from solar minimum. The results also support the idea that the largest flux tube expansion factors are located near the coronal hole/streamer interface, at least during the deepest part of the solar minimum period.

show abstract

Section: Introductionmentioning

confidence: 99%

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM

Strachan¹,

Panasyuk²,

Kohl³

et al. 2011

ApJ

View full text Add to dashboard Cite

show abstract

“…Observations from the University of California, San Diego (UCSD) [Coles and Kaufman, 1978] and Nagoya [Kofima and Kakinuma, 1987] [Hewish and Bravo, 1986].…”

Section: Introductionmentioning

confidence: 99%

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Jackson¹,

Hick²,

Kojima³

et al. 1998

J. Geophys. Res.

Self Cite

179

172

View full text Add to dashboard Cite

Abstract. We have produced a computer assisted tomography program that optimizes a three-dimensional model to fit observational data. We have used this program with interplanetary scintillation data from Nagoya, Japan, and Cambridge, England. The program iterates to a least squares solution fit of observed data using solar rotation and solar wind motion to provide perspective views of each point in space accessible to the observations. We plot the optimized model as Carrington maps in velocity V and density N e for the two data sets with resolutions of 10 ø in hellographic longitude and latitude. We map the model to 1 AU and compare this to in situ observations from the IMP spacecraft. Tomography methods can be used to improve upon the inherent averages made in the point P approximation used to display heliospheric data. IPS observations covering a large range of solar elongations and obtained over an extended period of time provide a global view of the inner heliosphere. The multiple perspectives required for tomographic analysis are provided by both solar rotation and outward solar wind motion. Effects due to the evolution of solar structures as they rotate during the period of observation can be minimized by selecting observations from a quiet part of the solar cycle. From this comparison we find12,049

show abstract

“…Now, with a well-established method, these conditions provide a perfect opportunity for it to be applied to new data when looking at interaction in the solar wind. Using this method with observations/measurements from other data sources, which are now more numerous than were available during the previous solar minimum, would also be advantageous where data exist; for example, CIR-type features detected with SolarTerrestrial Environment Laboratory (STELab) IPS (Kojima and Kakinuma, 1987) observations when using a kinematic solar-wind model (Jackson and Hick, 2005) to tomographically reconstruct the inner heliosphere and give good comparison with in-situ measurements by STEREO-A, Wind, and STEREO-B instrumentation (Bisi et al, 2009(Bisi et al, , 2010.…”

Section: Conclusion and Future Prospectsmentioning

confidence: 99%

Interplanetary Scintillation Observations of Stream Interaction Regions in the Solar Wind

et al. 2009

View full text Add to dashboard Cite

We present a summary of results from ten years of interplanetary scintillation (IPS) observations of stream interaction regions (SIRs) in the solar wind. Previous studies had shown that SIRs were characterized by intermediate-velocity solar wind and -in the case of compressive interactions -higher levels of scintillation. In this study we considered all cases of intermediate velocities in IPS observations from the European Incoherent SCATter (EISCAT) radar facility made at low-and mid-heliographic latitudes between 1994 and 2003. After dismissing intermediate-velocity observations which were associated with solar-wind transients (such as coronal mass ejections) we found that the remaining cases of intermediate velocities lay above coronal structures where stream interaction would be expected. An improved ballistic mapping method (compared to that used in earlier EISCAT studies of interaction regions) was used to identify the regions of raypath in IPS observations which might be expected to include interaction regions and to project these regions out to the distances of in-situ observations. The early stages of developing compression regions, consistent with their development on the leading edges of compressive stream interaction regions, were clearly detected as close to the Sun as 30 R , and further ballistic projection out to the distances of in-situ observations clearly associated these developing structures with density and velocity features characteristic of developed interaction regions in in-situ data in the cases when such data were available. The same approach was applied to study non-compressive interaction regions (shear layers) between solar-wind streams of different velocities where the stream interface lay at near-constant latitude and the results compared with those from compressive interaction regions. The results confirm that intermediate velocities seen in IPS observations above stream boundaries may arise from either detection of intermediate-velocity flow in compression regions, or from non-compressive shear layers. The variation in velocity about the mean determined from IPS measurements (representing the spread in velocity across that part of the raypath associated with the interaction region in the analysis) was comparable in compressive and non-compressive regions -a potentially interesting result which may contain important information on the geometry of developing SIRs. It is clear from these results that compressive and non-compressive interaction regions belong to the same class of stream -stream interaction, with the dominant mode determined by the latitudinal gradient of the stream interface. Finally, we discuss the results from this survey in the light of new data from the Heliospheric Imagers (HI) on the Solar TErrestrial RElations Observatory (STEREO) spacecraft and other instruments, and suggest possible directions for further work.

show abstract

Solar cycle evolution of solar wind speed structure between 1973 and 1985 observed with the interplanetary scintillation method

Cited by 132 publications

References 28 publications

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Interplanetary Scintillation Observations of Stream Interaction Regions in the Solar Wind

Contact Info

Product

Resources

About

Solar cycle evolution of solar wind speed structure between 1973 and 1985 observed with the interplanetary scintillation method

Cited by 132 publications

References 28 publications

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R☉DURING SOLAR MINIMUM

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R☉DURING SOLAR MINIMUM

Heliospheric tomography using interplanetary scintillation observations: 1. Combined Nagoya and Cambridge data

Interplanetary Scintillation Observations of Stream Interaction Regions in the Solar Wind

Contact Info

Product

Resources

About

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM

THE EVOLUTION OF PLASMA PARAMETERS ON A CORONAL SOURCE SURFACE AT 2.3R_☉DURING SOLAR MINIMUM