Main field influence on equatorial ionosphere

Quantifying solar flux and geomagnetic main field influence on the equatorial thermosphere-ionosphere system for timescales complementary to satellite missions.


  • Juli 2015 - Juni 2018


  • DFG, Projekt-Nummer Ma 2578/4-1

Principal Investigator

  • Jürgen Matzka (GFZ Potsdam)
  • Claudia Stolle (GFZ Potsdam)


  • Tarique Adnan Siddiqui (GFZ Potsdam)
  • Henning Lilienkamp (Universität Potsdam)
  • Gabiel Brando Soares (Observatorio Nacional, Rio de Janeiro)


  • Oscar Veliz (Instituto Geofísico del Perú, Jicamarca Radio Observatory, Lima, Peru)

Methods & Equipment

In order to analyse the sensitivity of the equatorial ionospheric current system, comprising the solar quiet current system and the equatorial electrojet, to solar cycle variations and to the secular variation of the geomagnetic main field, we analyse 51 years (1935–1985) of geomagnetic observatory data from Huancayo (HUA), Peru, operated by Instituto Geofísico del Perú. This period is ideal to analyse the influence of the main field strength on the amplitude of the quiet daily variation, since the main field decreases significantly from 1935 to 1985, while the distance of the magnetic equator to the observatory remains stable. To this end, we digitise some 19 years of hourly mean values of the geomagnetic records of the , which have not been available digitally at the World Data Centres. The sensitivity of the amplitude of the quiet daily variation to both solar cycle variations (in terms of sunspot numbers and solar flux F10.7) and changes of the geomagnetic main field strength (due to secular variation) are determined. We confirm an increase of equatorial ionospheric current system for the decreasing main field in this period.


  • Matzka, J., Siddiqui, T., Lilienkamp, H., Stolle, C., Veliz, O., 2017. Quantifying solar flux and geomagnetic main field influence on the equatorial ionospheric current system at the geomagnetic observatory Huancayo. J. Atmos. Solar-Terr. Phys. | GFZpublic |
  • Yamazaki, Y., Stolle, C., Matzka, J., Siddiqui, T., Lühr, H., Alken, P. (2017 online): Longitudinal Variation of the Lunar Tide in the Equatorial Electrojet. - Journal of Geophysical Research. | GFZpublic |


Jürgen Matzka
Group Leader
Dr. Jürgen Matzka
Lindenstr. 7
Building H 1, Room 213
14823 Niemegk
+49 33843 624-18