A case study of HF radar spectral width in the post midnight magnetic local time sector and its relationship to the polar cap boundary

The aim of this paper is to advance the current understanding of the spectral width parameter observed by coherent high frequency (HF) radars. In particular, we address the relationship of a frequently observed gradient, between low ( < 200 m/s) and high ( > 200 m/s) spectral width, to magneto...

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Bibliographic Details
Published in:Annales Geophysicae
Main Authors: Woodfield, Emma E., Davies, J. A., Eglitis, P., Lester, M.
Format: Article in Journal/Newspaper
Language:English
Published: European Geosciences Union (EGU) 2013
Subjects:
Science & Technology
Physical Sciences
Astronomy & Astrophysics
Geosciences
Multidisciplinary
Meteorology & Atmospheric Sciences
Geology
ionosphere
auroral ionosphere
ionospheric irregularities
AURORAL EMISSION
EISCAT SVALBARD
F-REGION
CUSP
SUPERDARN
SYSTEM
PRECIPITATION
SIGNATURES
DYNAMICS
Svalbard
EISCAT
Online Access:http://www.ann-geophys.net/20/501/2002/angeo-20-501-2002.html
http://hdl.handle.net/2381/28304
https://doi.org/10.5194/angeo-20-501-2002
Description
Summary:The aim of this paper is to advance the current understanding of the spectral width parameter observed by coherent high frequency (HF) radars. In particular, we address the relationship of a frequently observed gradient, between low ( < 200 m/s) and high ( > 200 m/s) spectral width, to magnetospheric boundaries. Previous work has linked this gradient in the spectral width, in the nightside sector of magnetic local time, to the Polar Cap Boundary (PCB), and also to the boundary between the Central Plasma Sheet (CPS) and the Plasma Sheet Boundary Layer (PSBL). The present case study investigates the former by comparison with the 630.0 nm optical emission. No suitable data were available to test the second of the two hypotheses. It is found that during the interval in question the spectral width gradient is within the region of the 630.0 nm optical emission. A comparison of coherent and incoherent scatter radar data is also conducted, which indicates that values of high spectral width are typically collocated with elevated F-region electron temperatures. We conclude that the high spectral width region in the interval under study is associated with particle precipitation and also that the spectral width gradient is not a reliable method for locating the PCB. Peer-reviewed Publisher Version

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