scholarly journals EISCAT measurements of solar wind velocity and the associated level of interplanetary scintillation

2002 ◽  
Vol 20 (9) ◽  
pp. 1279-1289 ◽  
Author(s):  
R. A. Fallows ◽  
P. J. S. Williams ◽  
A. R. Breen
Keyword(s):  
Solar Wind ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Solar Wind Plasma ◽  
Scintillation Index ◽  
Line Of Sight ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
Interplanetary Physics ◽  
Eiscat Measurements

Abstract. A relative scintillation index can be derived from EISCAT observations of Interplanetary Scintillation (IPS) usually used to study the solar wind velocity. This provides an ideal opportunity to compare reliable measurements of the solar wind velocity derived for a number of points along the line-of-sight with measurements of the overall level of scintillation. By selecting those occasions where either slow- or fast-stream scattering was dominant, it is shown that at distances from the Sun greater than 30 RS , in both cases the scintillation index fell with increasing distance as a simple power law, typically as R-1.7. The level of scintillation for slow-stream scattering is found to be 2.3 times the level for fast-stream scattering.Key words. Interplanetary physics (solar wind plasma)

scholarly journals Observations of interplanetary scintillation during the 1998 Whole Sun Month: a comparison between EISCAT, ORT and Nagoya data

2000 ◽  
Vol 18 (9) ◽  
pp. 1003-1008 ◽  
Author(s):  
P. J. Moran ◽  
S. Ananthakrishnan ◽  
V. Balasubramanian ◽  
A. R. Breen ◽  
A. Canals ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Wind Velocity ◽  
Solar Physics ◽  
Solar Wind Plasma ◽  
Interplanetary Scintillation ◽  
Velocity Measurements ◽  
Plasma Sources ◽  
Interplanetary Physics ◽  
Instruments And Techniques ◽  
Good Agreement

Abstract. Observations of interplanetary scintillation (IPS) allow accurate solar wind velocity measurements to be made at all heliographic latitudes and at a range of distances from the Sun. The data may be obtained with either single, double or multiple antennas, each requiring a different method of analysis. IPS data taken during the 1998 whole sun month (30th July-31st August 1998) by EISCAT, the ORT (Ooty Radio Telescope), India, and the Nagoya IPS system, Japan, allow the results of individual methods of analysis to be compared. Good agreement is found between the velocity measurements using each method, and when combined an improved understanding of the structure of the solar wind can be obtained.Key words: Interplanetary physics (solar wind plasma; sources of the solar wind) - Solar physics, astrophysics and astronomy (instruments and techniques)

scholarly journals Interplanetary Scintillation - Preliminary Observations at 103 MHz

1980 ◽  
Vol 91 ◽  
pp. 405-408
Author(s):  
S. K. Alurkar ◽  
R. V. Bhonsle
Keyword(s):  
Solar Wind ◽  
Solar Wind Plasma ◽  
Scintillation Index ◽  
Interplanetary Scintillation ◽  
Antenna Aperture ◽  
Scale Size ◽  
Intensity Fluctuations

A 3-station interplanetary scintillation (IPS) observatory is being developed mainly with a view to study the solar wind plasma. The first IPS telescope operating at 103 MHz at Thaltej near Ahmedabad has been put into regular operation since April 1979. With only half the antenna aperture (≃2500 m2) presently in use, observations of 8-10 sources are being made to calculate scintillation index, temporal spectrum of intensity fluctuations and scale size of density irregularities.

scholarly journals EISCAT measurements of the solar wind

1996 ◽  
Vol 14 (12) ◽  
pp. 1235-1245 ◽  
Author(s):  
A. R. Breen ◽  
W. A. Coles ◽  
R. R. Grall ◽  
M. T. Klinglesmith ◽  
J. Markkanen ◽  
...  
Keyword(s):  
Solar Wind ◽  
Slow Solar Wind ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
Final Velocity ◽  
Flow Vector ◽  
Fast Wind ◽  
Interaction Regions ◽  
Slow Wind ◽  
Eiscat Measurements

Abstract. EISCAT observations of interplanetary scintillation have been used to measure the velocity of the solar wind at distances between 15 and 130 R⊙ (solar radii) from the Sun. The results show that the solar wind consists of two distinct components, a fast stream with a velocity of ~800 km s–1 and a slow stream at ~400 km s–1. The fast stream appears to reach its final velocity much closer to the Sun than expected. The results presented here suggest that this is also true for the slow solar wind. Away from interaction regions the flow vector of the solar wind is purely radial to the Sun. Observations have been made of fast wind/slow wind interactions which show enhanced levels of scintillation in compression regions.

Scintillation Measurements of the Solar Wind Velocity in Strong Scattering near the Sun

Solar Physics ◽  
2013 ◽  
Vol 283 (2) ◽  
pp. 519-540 ◽  
Author(s):  
M. Kojima ◽  
W. A. Coles ◽  
M. Tokumaru ◽  
K. Fujiki
Keyword(s):  
Solar Wind ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
The Sun ◽  
Strong Scattering

scholarly journals Extremely long baseline interplanetary scintillation measurements of solar wind velocity

2006 ◽  
Vol 111 (A8) ◽  
Author(s):  
A. R. Breen ◽  
R. A. Fallows ◽  
M. M. Bisi ◽  
P. Thomasson ◽  
C. A. Jordan ◽  
...  
Keyword(s):  
Solar Wind ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Interplanetary Scintillation ◽  
Long Baseline

scholarly journals Enhanced Radio Source Scintillation due to Comet Austin (1989c1)

1991 ◽  
Vol 44 (5) ◽  
pp. 565 ◽  
Author(s):  
P Janardhan ◽  
SK Alurkar ◽  
AD Bobra ◽  
OB Slee
Keyword(s):  
Solar Wind ◽  
Radio Source ◽  
Electron Density ◽  
Density Variation ◽  
Scintillation Index ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
Electron Density Variation ◽  
Comet Halley

Enhanced scintillations in the direction of the quasar 2204+29 (3C441) were observed on 13 May 1990 when the tail of Comet Austin passed in front of it. Comparison with previous observations at 103, 327 and 408 MHz of Comet Halley and at 408 MHz of Comet Wilson show that proper occultation geometry is essential for observing enhanced scintillations. It has been shown that the solar elongation ? during such observations should be large, typically greater than 60� and in no case less than 30� at 103 MHz. At the time of the occultation the scintillation index (r.m.s./mean source flux) was greater than that expected for this source by a factor of 3. The r.m.s. electron density variation /IN, at a distance of 0�9 A.U. from the sun and 7�3� downstream of the nucleus, was found to be 6 cm-3 as compared with 1 cm-3 for the normal solar wind at 1 A.U. The corresponding scale sizes of the turbulence were found to be much finer than normally found in interplanetary scintillation (IPS) caused by the solar wind.

scholarly journals Tomography of the Solar Wind using Interplanetary Scintillation

2000 ◽  
Vol 179 ◽  
pp. 445-446 ◽  
Author(s):  
Divya Oberoi ◽  
A. Pramesh Rao
Keyword(s):  
Solar Wind ◽  
Solar Surface ◽  
Line Of Sight ◽  
Weighted Sum ◽  
The Sun ◽  
Interplanetary Scintillation ◽  
The Earth ◽  
Compact Radio Source ◽  
Different Sources ◽  
Inner Heliosphere

Extended AbstractInterplanetary scintillation (IPS) measurements are sensitive to a weighted sum of the properties of solar wind (SW) along the line-of-sight (los) to a distant compact radio source. Mapping alosback to the surface of the Sun provides information of the sites of origin of the SW sampled by thelos. By observing different sources, lines-of-sight can be so chosen that they sample overlapping regions of Solar surface. In addition, the rotation of the Sun causes the long lived features in the SW to co-rotate, much like the twirling skirt of a ballerina, presenting different perspective views to the Earth based observers. These properties raise the possibility that systematic IPS observations can be inverted to give the maps of density and the velocity of the SW in the inner heliosphere, using techniques similar to tomography.

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