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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 36, issue 2 | Copyright

Special issue: Dynamics and interaction of processes in the Earth and its...

Ann. Geophys., 36, 679-693, 2018
https://doi.org/10.5194/angeo-36-679-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 26 Apr 2018

Regular paper | 26 Apr 2018

Climatology of GPS signal loss observed by Swarm satellites

Chao Xiong1, Claudia Stolle1,2, and Jaeheung Park3,4 Chao Xiong et al.
  • 1GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
  • 2Faculty of Science, University of Potsdam, Potsdam, Germany
  • 3Korea Astronomy and Space Science Institute, Daejeon, South Korea
  • 4Department of Astronomy and Space Science, University of Science and Technology, Daejeon, South Korea

Abstract. By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20° magnetic latitude (MLAT) and high latitudes above 60° MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20°, and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0Hz, a PLL bandwidth of 0.5Hz is a more suitable value for the Swarm receiver.

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