@misc{SiddiquiLuehrStolleetal.2015,
  author    = {Siddiqui, Tarique Adnan and L{\"u}hr, H. and Stolle, Claudia and Park, J.},
  title     = {Relation between stratospheric sudden warming and the lunar effect on the equatorial electrojet based on Huancayo recordings},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {517},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40956},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409564},
  pages     = {9},
  year      = {2015},
  abstract  = {It has been known for many decades that the lunar tidal influence in the equatorial electrojet (EEJ) is noticeably enhanced during Northern Hemisphere winters. Recent literature has discussed the role of stratospheric sudden warming (SSW) events behind the enhancement of lunar tides and the findings suggest a positive correlation between the lunar tidal amplitude and lower stratospheric parameters (zonal mean air temperature and zonal mean zonal wind) during SSW events. The positive correlation raises the question whether an inverse approach could also be developed which makes it possible to deduce the occurrence of SSW events before their direct observations (before 1952) from the amplitude of the lunar tides. This study presents an analysis technique based on the phase of the semi-monthly lunar tide to determine the lunar tidal modulation of the EEJ. A statistical approach using the superposed epoch analysis is also carried out to formulate a relation between the EEJ tidal amplitude and lower stratospheric parameters. Using these results, we have estimated a threshold value for the tidal wave power that could be used to identify years with SSW events from magnetic field observations.},
  language  = {en}
}
@misc{ParkLuehrStolleetal.2015,
  author    = {Park, J. and L{\"u}hr, H. and Stolle, Claudia and Malhotra, G. and Baker, J. B. H. and Buchert, Stephan and Gill, R.},
  title     = {Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {503},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-40841},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-408417},
  pages     = {7},
  year      = {2015},
  abstract  = {Plasma convection in the high-latitude ionosphere provides important information about magnetosphere-ionosphere-thermosphere coupling. In this study we estimate the along-track component of plasma convection within and around the polar cap, using electron density profiles measured by the three Swarm satellites. The velocity values estimated from the two different satellite pairs agree with each other. In both hemispheres the estimated velocity is generally anti-sunward, especially for higher speeds. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network data. Our method can supplement currently available instruments for ionospheric plasma velocity measurements, especially in cases where these traditional instruments suffer from their inherent limitations. Also, the method can be generalized to other satellite constellations carrying electron density probes.},
  language  = {en}
}