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A new pair of indices to describe the relationship between ionospheric disturbances and geomagnetic activity
Author(s) -
Chen Zhou,
Wang JingSong,
Huang ChunMing,
Huang LinFeng
Publication year - 2014
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2014ja020438
Subject(s) - earth's magnetic field , ionosphere , ionosonde , correlation coefficient , geodesy , tec , index (typography) , geology , atmospheric sciences , geophysics , physics , mathematics , statistics , magnetic field , electron density , quantum mechanics , electron , world wide web , computer science
In this paper, a new ionospheric index pair—the single‐station index ( J s) and the planetary index ( J p), which describe ionospheric disturbances—is constructed using the spectral‐whitening method. Observations covering more than 30 years and obtained from 21 ionosonde stations widely distributed across middle‐ and low‐latitude areas are used in the study. Variations in the J s index at all stations generally follow the variation of the geomagnetic Dst index during periods of strong to moderate geomagnetic activity. Nevertheless, the inertial response of J s to weak geomagnetic activity results in a weak correlation between J s and Dst . The extrema of J s and Dst during the same geomagnetic activity period have a much higher correlation coefficient, since they avoid the delaying effect of the ionospheric response to geomagnetic activity. To smooth out local differences among ionospheric disturbances, the J p index was defined as the means of all J s indices and so describes ionospheric disturbances at the planetary scale. The J p index is significantly correlated to the Dst index, and the correlation coefficient between the extrema of J p and Dst is up to −0.8. This correlation remains robust when the data set length varies, and data from approximately 10 stations are sufficient to derive a reasonable estimate of J p. The quantitative relationship between J p and Dst can be used to reproduce J p by adopting Dst as the precursor, and this raises the possibility of predicting planetary ionospheric disturbances based on geomagnetic activity.