Spatial and temporal variation of total electron content as revealed by principal component analysis
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...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/34/1109/2016/angeo-34-1109-2016.pdf |
| Summary: | 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. |
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| ISSN: | 0992-7689 1432-0576 |