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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 33, issue 9
Ann. Geophys., 33, 1117–1133, 2015
https://doi.org/10.5194/angeo-33-1117-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 33, 1117–1133, 2015
https://doi.org/10.5194/angeo-33-1117-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 14 Sep 2015

Regular paper | 14 Sep 2015

Polar cap patches observed during the magnetic storm of November 2003: observations and modeling

C. E. Valladares1, T. Pedersen2, and R. Sheehan1 C. E. Valladares et al.
  • 1Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts, USA
  • 2Space Vehicle Directorate, Air Force Research Laboratory, Kirtland Air Force Base, New Mexico, USA

Abstract. We present multi-instrumented measurements and multi-technique analysis of polar cap patches observed early during the recovery phase of the major magnetic storm of 20 November 2003 to investigate the origin of the polar cap patches. During this event, the Qaanaaq imager observed elongated polar cap patches, some of which containing variable brightness; the Qaanaaq digisonde detected abrupt NmF2 fluctuations; the Sondrestrom incoherent scatter radar (ISR) measured patches placed close to but poleward of the auroral oval–polar cap boundary; and the DMSP-F13 satellite intersected topside density enhancements, corroborating the presence of the patches seen by the imager, the digisonde, and the Sondrestrom ISR. A 2-D cross-correlation analysis was applied to series of two consecutive red-line images, indicating that the magnitude and direction of the patch velocities were in good agreement with the SuperDARN convection patterns. We applied a back-tracing analysis to the patch locations and found that most of the patches seen between 20:41 and 21:29 UT were likely transiting the throat region near 19:41 UT. Inspection of the SuperDARN velocities at this time indicates spatial and temporal collocation of a gap region between patches and large (1.7 km s−1) line-of-sight velocities. The variable airglow brightness of the patches observed between 20:33 and 20:43 UT was investigated using the numerical Global Theoretical Ionospheric Model (GTIM) driven by the SuperDARN convection patterns and a variable upward/downward neutral wind. Our numerical results indicate that variations in the airglow intensity up to 265 R can be produced by a constant 70 m s−1 downward vertical wind.

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We present multi-instrument measurements and multi-technique analysis of polar cap patches observed early during the recovery phase of the major magnetic storm of November 20 2003. During this event, the Qaanaaq imager observed variable airglow brightness of the patches between 20:33 and 20:43UT, probably associated with a large-scale gravity wave. Our numerical results indicate that variations in the airglow intensity up to 265R can be produced by a constant 70m/s downward vertical wind.
We present multi-instrument measurements and multi-technique analysis of polar cap patches...
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