Comparison of high latitude thermospheric meridional neutral wind climatologies

• Main Author: Griffin, Eoghan Michael
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: UCL (University College London) 2000
• Subjects: Earth sciences; Neutral winds; Thermosphere; Kiruna; EISCAT
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10097916/1/Comparison_of_high_latitude_th.pdf; https://discovery.ucl.ac.uk/id/eprint/10097916/

The combination of the long term databases of measurements from the Kiruna Fabry-Perot Interferometer and the EISCAT incoherent scatter radar, both covering more than a solar cycle of data, allows a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. This allows the climatological behaviour of the neutral wind at high latitudes to be investigated, including the influence of both solar activity and season. Two techniques are applied to derive winds from the EISCAT database, one from previous work using the standard technique for incoherent scatter radars, and a new dataset derived using the Meridional Wind Model implementation of servo theory with the EISCAT data as input. The latter technique also uses contemporaneous EISCAT electric field data for correction to the equivalent servo winds. Alongside the local measurements from experiment, model predictions of the behaviour of the winds can also be compared. These have been included and use both empirical sources as in the Horizontal Wind Model and Meridional Wind Model with International Reference Ionosphere input, and also the results from a first principles theoretical model, the UCL Coupled Thermosphere and Ionosphere Model. Comparisons are made between the results from these techniques for each of eight categories corresponding to the four seasons, centred around the equinoxes and solstices, and for two solar activity levels. The detailed comparisons in each case and the implications of the results for the ability of the models to predict the long term behaviour of the winds and also for the degree of agreement between the techniques based on local measurements are discussed. Conclusions are drawn as to the major influences on the climatological behaviour of the wind at this latitude and the possibilities for further work to improve both experimental and modelling efforts.