Open AccessIPDP geomagnetic pulsations and their relation to coronal holes and high speed solar wind streams
Author(s) -
S. Bravo,
J.A López Cruz Abeyro
Publication year - 1998
Publication title -
geofísica internacional
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.159
H-Index - 26
ISSN - 0016-7169
DOI - 10.22201/igeof.00167169p.1998.37.1.2159
Subject(s) - coronal hole , sunspot number , solar wind , sunspot , earth's magnetic field , wind speed , coronal plane , solar minimum , physics , flux (metallurgy) , solar cycle , atmospheric sciences , geodesy , geology , meteorology , coronal mass ejection , magnetic field , medicine , materials science , quantum mechanics , metallurgy , radiology
The frequency of occurrence of intervals of pulsations of diminishing periods (IPDP) has shown a very surprising inverse relation to the sunspot number. In this paper we take the annual frequency of occurrence of IPDPs at Sodankyla station for the period 1974 to 1985 and find that they correlate msitivelv with coronal hole area with a correlation coefficient of 0.77. This suggests a physical relationship between this kind of pulsations and the high speed streams (HSSs) in the solar wind coming from the holes. We compare the annual rate of lPDPs to the annual number of coronal-hole associated HSSs having a velocity equal to or higher than 550 kmls for the period from 1974 to 1982. We find a good agreement during the descending part of the solar cycle and around the maximum, but during the minimum and the first years of the ascending phase were more frequent than HSSs. We conclude that IPDPs are related to some solar wind characteristics in HSSs and we discuss a possible reason for the differences during the minimum.