Open AccessInterplanetary scintillation observations for the solar wind disappearance event of May 1999
Author(s) -
Vats Hari Om,
Sawant H. S.,
Oza Rupal,
Iyer K. N.,
Jadhav Ravi
Publication year - 2001
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000ja000254
Subject(s) - interplanetary scintillation , solar wind , scintillation , interplanetary medium , physics , interplanetary spaceflight , atmospheric sciences , coronal mass ejection , astronomy , plasma , astrophysics , optics , quantum mechanics , detector
In this article we present ground‐based interplanetary scintillation (IPS) measurements at 103 and 327 MHz for the period of the solar wind disappearance event of May 1999 as seen by various space probes. The solar wind velocity measurements at 327 MHz showed a variable solar wind velocity during this period at a distance of ∼0.5 AU from the Sun. The average solar wind velocity from three radio sources varied in the range of 200–300 km s −1 . The scintillation index measurements at 103 MHz indicate that plasma density was very low in the interplanetary medium closer to the Earth and that the density was normal away from it during May 11–13. The scintillation index was enhanced significantly on May 14 after the disappearance event. The comparison with the in situ observations shows that the effect is dramatic in IPS observations. IPS and in situ measurements show that a large, tenuous, and slow plasma cloud engulfed our planet around this time, which could be because of a corotating low‐density narrow stream. From the source (Sun) point of view, this was mostly a normal plasma flow in most of the interplanetary medium.