Statistical observations of spatial characteristics of Pi1B pulsations

Document Type

Article

Publication Date

11-1-2007

Abstract

We have examined the spatial and temporal correlation of high-latitude Pi1B and Pi2 pulsations, mid-latitude Pi2 pulsations, and auroral substorm onsets identified in the IMAGE far ultraviolet imager (FUV) data. Numerous search coil and fluxgate magnetometers at high latitudes (65-80° in Antarctica and Greenland) and mid-latitude fluxgate magnetometers are used. We find that Pi1B onset times agree well with onset times of intense isolated auroral substorms identified by the IMAGE FUV instrument: Pi1B onsets occurred within the 2 min cadence of the imager. For any given event, we find that Pi1B are localized to approximately 4 h of local time and 7° of magnetic latitude relative to the initial auroral brightening location as observed by IMAGE FUV. Not surprisingly, we also find that Pi1B pulsations occur typically between 2100 and 0200 MLT. Comparison to Pi2 records from these and other lower-latitude stations shows that in almost all cases Pi1B activity coincides within ±2 min with Pi2 activity. Power law fits showed that Pi1B amplitude fell off with distance-2.9 for two strong events (i.e., similar to the r-3 falloff of the signal from a dipolar source), and only slightly more rapidly than the falloff of Pi2 activity (d-2.8). Given the global nature of Pi2 pulsations versus the localized nature of Pi1B events in this study, we conclude that the mechanism that drives Pi1B pulsations is likely different from that responsible for Pi2 pulsations. © 2007 Elsevier Ltd. All rights reserved.

Identifier

35448981389 (Scopus)

Publication Title

Journal of Atmospheric and Solar Terrestrial Physics

External Full Text Location

https://doi.org/10.1016/j.jastp.2007.07.015

ISSN

13646826

First Page

1775

Last Page

1796

Issue

15

Volume

69

Grant

ANT-0442648

Fund Ref

National Science Foundation

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