Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8139794 | Journal of Atmospheric and Solar-Terrestrial Physics | 2017 | 16 Pages |
Abstract
For the 2007 to 2014 period, we use a statistical approach to evaluate the performance of Tsyganenko and Sitnov [2005] semi-empirical model (TS05) in estimating the magnetospheric transient signal observed at four Northern Hemisphere mid-latitude ground stations: Coimbra, Portugal; Panagyurishte, Bulgary; Novosibirsk, Russia and Boulder, USA. Using hourly mean data, we find that the TS05 performance is clearly better for the X (North-South) than for the Y (East-West) field components and for more geomagnetically active days as determined by local K-indices. In â¼50% (X) and â¼30% (Y) of the total number of geomagnetically active days, correlation values yield râ¥0.7. During more quiet conditions, only â¼30% (X) and â¼15% (Y) of the number of analyzed days yield râ¥0.7. We compute separate contributions from different magnetospheric currents to data time variability and to signal magnitude. During more active days, all tail, symmetric ring and partial ring currents contribute to the time variability of X while the partial ring and field aligned currents contribute most to the time variability of Y. The tail and symmetric ring currents are main contributors to the magnitude of X. In the best case estimations when râ¥0.7, remaining differences between observations and TS05 predictions could be explained by global induction in the Earth's upper layers and crustal magnetization. The closing of field aligned currents through the Earth's center in the TS05 model seems to be mainly affecting the Y magnetospheric field predictions.
Keywords
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Physical Sciences and Engineering
Earth and Planetary Sciences
Geophysics
Authors
Yvelice Castillo, Maria Alexandra Pais, João Fernandes, Paulo Ribeiro, Anna L. Morozova, Fernando J.G. Pinheiro,