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AGU: Journal of Geophysical Research, Space Physics

 

Keywords

  • equatorial anomaly
  • morphology
  • singular value decomposition

Index Terms

  • Ionosphere: Equatorial ionosphere
  • Ionosphere: Ionospheric irregularities
  • Ionosphere: Ionosphere/atmosphere interactions
  • Ionosphere: Instruments and techniques
Abstract
Cited By (8)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, A08308, 10 PP., 2005
doi:10.1029/2004JA010830

Method for characterization of the equatorial anomaly using image subspace analysis of Global Ultraviolet Imager data

S. B. Henderson

Department of Electrical and Computer Engineering, Utah State University, Logan, Utah, USA

C. M. Swenson

Department of Electrical and Computer Engineering, Utah State University, Logan, Utah, USA

J. H. Gunther

Department of Electrical and Computer Engineering, Utah State University, Logan, Utah, USA

A. B. Christensen

Fountain Valley, California, USA

L. J. Paxton

Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA

We present a method for measuring equatorial anomaly (EA) morphology using nighttime 135.6 nm radiance observed by the Global Ultraviolet Imager (GUVI) on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft. The method uses the singular value decomposition to estimate an along-track intensity profile as TIMED passes over the EA. The method is unique in that it removes intensity depletions due to equatorial plasma bubbles (EPBs) from the estimated intensity profile. Thus the profiles reflect plasma distribution in response to equatorial E × B drifts and neutral winds. A set of metrics including crest maximum intensity and its latitude are extracted from the intensity profiles. EPBs are also detected. Preliminary results from this method using GUVI equinox data from 2002 are compared with results from a ground-based ionosonde EA morphology study by Whalen (2001) in the western American sector. EPB occurrence rates are also compared with results from Huang et al. (2001), who used DMSP in situ density measurements to detect EPBs. General agreement was found in both studies with some localized differences. These results indicate that this method provides a valuable means of simultaneously studying EA morphology and EPB occurrence rates. Since the TIMED spacecraft precesses through all local times in 60 days, this method can be used to extend ground-based measurements to study the global relationship between E × B drifts and plasma distribution in the EA and how these relate to the occurrence of large-scale EPBs.

Received 5 October 2004; accepted 3 May 2005; published 25 August 2005.

Citation: Henderson, S. B., C. M. Swenson, J. H. Gunther, A. B. Christensen, and L. J. Paxton (2005), Method for characterization of the equatorial anomaly using image subspace analysis of Global Ultraviolet Imager data, J. Geophys. Res., 110, A08308, doi:10.1029/2004JA010830.

Cited By

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