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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 25, issue 9
Ann. Geophys., 25, 2019-2027, 2007
https://doi.org/10.5194/angeo-25-2019-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 25, 2019-2027, 2007
https://doi.org/10.5194/angeo-25-2019-2007
© Author(s) 2007. This work is distributed under
the Creative Commons Attribution 3.0 License.

  02 Oct 2007

02 Oct 2007

Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment

L. Liu1, W. Wan1, M.-L. Zhang1, B. Ning1, S.-R. Zhang2, and J. M. Holt2 L. Liu et al.
  • 1Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
  • 2Haystack Observatory, Massachusetts Institute of Technology, Westford, MA, USA

Abstract. A 30-day incoherent scatter radar (ISR) experiment was conducted at Millstone Hill (288.5° E, 42.6° N) from 4 October to 4 November 2002. The altitude profiles of electron density Ne, ion and electron temperature (Ti and Te), and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height Hp, vertical scale height VSH, Chapman scale height Hm, ion velocity, and the relative altitude gradient of plasma temperature (dTp/dh)/Tp, as well as the F2 layer electron density (NmF2) and height (hmF2). These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed conditions. Results show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions, while the main feature of the scale heights, as well as other parameters, deviated significantly from their median behaviors under disturbed conditions. The enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights, as well as the shape of the topside electron density profiles. Over Millstone Hill, the diurnal behaviors of the median VSH and Hm are very similar to each other and are not so tightly correlated with that of the plasma scale height Hp or the plasma temperature. The present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and dynamics. The values of VSH/Hp tend to decrease as (dTp/dh)/Tp becomes larger or the dynamic processes become enhanced.

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