Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.621 IF 1.621
  • IF 5-year value: 1.614 IF 5-year
    1.614
  • CiteScore value: 1.61 CiteScore
    1.61
  • SNIP value: 0.900 SNIP 0.900
  • IPP value: 1.58 IPP 1.58
  • SJR value: 0.910 SJR 0.910
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 80 Scimago H
    index 80
  • h5-index value: 24 h5-index 24
Volume 34, issue 12
Ann. Geophys., 34, 1109-1117, 2016
https://doi.org/10.5194/angeo-34-1109-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: The 14th International Symposium on Equatorial Aeronomy

Ann. Geophys., 34, 1109-1117, 2016
https://doi.org/10.5194/angeo-34-1109-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 29 Nov 2016

Regular paper | 29 Nov 2016

Spatial and temporal variation of total electron content as revealed by principal component analysis

Elsayed R. Talaat1,a and Xun Zhu1 Elsayed R. Talaat and Xun Zhu
  • 1The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
  • anow at: Heliophysics Division, NASA Headquarters, Washington, D.C. 20546, USA

Abstract. Eleven years of global total electron content (TEC) data derived from the assimilated thermosphere–ionosphere electrodynamics general circulation model are analyzed using empirical orthogonal function (EOF) decomposition and the corresponding principal component analysis (PCA) technique. For the daily averaged TEC field, the first EOF explains more than 89% and the first four EOFs explain more than 98% of the total variance of the TEC field, indicating an effective data compression and clear separation of different physical processes. The effectiveness of the PCA technique for TEC is nearly insensitive to the horizontal resolution and the length of the data records. When the PCA is applied to global TEC including local-time variations, the rich spatial and temporal variations of field can be represented by the first three EOFs that explain 88% of the total variance. The spectral analysis of the time series of the EOF coefficients reveals how different mechanisms such as solar flux variation, change in the orbital declination, nonlinear mode coupling and geomagnetic activity are separated and expressed in different EOFs. This work demonstrates the usefulness of using the PCA technique to assimilate and monitor the global TEC field.

Publications Copernicus
Special issue
Download
Short summary
Global total electron content data derived from the assimilated thermosphere–ionosphere model are analyzed using empirical orthogonal function (EOF) decomposition and the principal component analysis technique. The spectral analysis of the time series of the EOF coefficients reveals how different mechanisms such as solar flux variation, change in the orbital declination, nonlinear mode coupling and geomagnetic activity are separated and expressed in different EOFs.
Global total electron content data derived from the assimilated thermosphere–ionosphere model...
Citation
Share