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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 22, issue 3
Ann. Geophys., 22, 849–862, 2004
https://doi.org/10.5194/angeo-22-849-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 22, 849–862, 2004
https://doi.org/10.5194/angeo-22-849-2004
© Author(s) 2004. This work is distributed under
the Creative Commons Attribution 3.0 License.

  19 Mar 2004

19 Mar 2004

Comparison of high-latitude thermospheric meridionalwinds I: optical and radar experimental comparisons

E. M. Griffin, I. C. F. Müller-Wodarg, A. Aruliah, and A. Aylward E. M. Griffin et al.
  • Atmospheric Physics Laboratory, University College London, 67-73 Riding House Street, London W1W 7EJ, UK

Abstract. Thermospheric neutral winds at Kiruna, Sweden (67.4°N, 20.4°E) are compared using both direct optical Fabry-Perot Interferometer (FPI) measurements and those derived from European incoherent scatter radar (EISCAT) measurements. This combination of experimental data sets, both covering well over a solar cycle of data, allows for a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. Uniquely in this study the EISCAT measurements are used to provide winds for comparison using two separate techniques: the most popular method based on the work of Salah and Holt (1974) and the Meridional Wind Model (MWM) (Miller et al., 1997) application of servo theory. The balance of forces at this location that produces the observed diurnal pattern are investigated using output from the Coupled Thermosphere and Ionosphere (CTIM) numerical model. Along with detailed comparisons from short periods the climatological behaviour of the winds have been investigated for seasonal and solar cycle dependence using the experimental techniques. While there are features which are consistent between the 3 techniques, such as the evidence of the equinoctial asymmetry, there are also significant differences between the techniques both in terms of trends and absolute values. It is clear from this and previous studies that the high-latitude representation of the thermospheric neutral winds from the empirical Horizontal Wind Model (HWM), though improved from earlier versions, lacks accuracy in many conditions. The relative merits of each technique are discussed and while none of the techniques provides the perfect data set to address model performance at high-latitude, one or more needs to be included in future HWM reformulations.

Key words. Meteorology and atmospheric dynamics (thermospheric dynamics), Ionosphere (ionosphere-atmosphere interactions, auroral ionosphere)

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