Are dayside long-period pulsations related to the cusp?

We compare simultaneous observations of long-period ultra-low-frequency (ULF) wave activity from a Svalbard/IMAGE fluxgate magnetometer latitudinal profile covering the expected cusp geomagnetic latitudes. Irregular Pulsations at Cusp Latitudes (IPCL) and narrowband Pc5 waves are found to be a ubiqu...

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Bibliographic Details
Published in:Annales Geophysicae
Main Authors: Pilipenko, V., Belakhovsky, V., Engebretson, M. J., Kozlovsky, A., Yeoman, T.
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2015
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article
Verlagsveröffentlichung
Svalbard
Svalbard Archipelago
Online Access:https://doi.org/10.5194/angeo-33-395-2015
https://noa.gwlb.de/receive/cop_mods_00017096
https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00017051/angeo-33-395-2015.pdf
https://angeo.copernicus.org/articles/33/395/2015/angeo-33-395-2015.pdf
Description
Summary:We compare simultaneous observations of long-period ultra-low-frequency (ULF) wave activity from a Svalbard/IMAGE fluxgate magnetometer latitudinal profile covering the expected cusp geomagnetic latitudes. Irregular Pulsations at Cusp Latitudes (IPCL) and narrowband Pc5 waves are found to be a ubiquitous element of ULF activity in the dayside high-latitude region. To identify the ionospheric projections of the cusp, we use the width of return signal of the Super Dual Auroral Radar Network (SuperDARN) radar covering the Svalbard archipelago, predictions of empirical cusp models, augmented whenever possible by Defense Meteorological Satellite Program (DMSP) identification of magnetospheric boundary domains. The meridional spatial structure of broadband dayside Pc5–6 pulsation spectral power has been found to have a localized latitudinal peak, not under the cusp proper as was previously thought, but several degrees southward from the equatorward cusp boundary. The earlier claims of the dayside monochromatic Pc5 wave association with the open–closed boundary also seems doubtful. Transient currents producing broadband Pc5–6 probably originate at the low-latitude boundary layer/central plasma sheet (LLBL/CPS) interface, though such identification with available DMSP data is not very precise. The occurrence of broadband Pc5–6 pulsations in the dayside boundary layers is a challenge to modelers because so far their mechanism has not been firmly identified.

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