Publication Date:
2017-02-16
Description:
We report the results of a model validation study that assessed how well several ionospheric models captured the slant total electron content, especially at low latitudes near the Equatorial Ionization Anomaly, where horizontal and vertical density gradients are large. We assessed NeQuick, IRI-2007, IRI-2012, SAMI-3, and the Utah State University version of the Global Assimilation of Ionospheric Measurements (GAIM) model. We used slant total electron content measurements made by the COSMIC constellation during May 5–June 20, 2012 to test GAIM, NeQuick, IRI-2007, and IRI-2012 and during October 1, 2011 – December 31, 2011 to test SAMI-3, as the SAMI-3 model runs were not available for the 2012 time frame. We found that the GAIM data assimilation model showed the lowest biases, although all of the models typically agreed with the COSMIC measurements to ~8% in the worst case. One area of concern with all of the models was that the mean percentage difference between the COSMIC measurements and the calculated TEC showed significant scatter, 〉15% at the 1-sigma level; this was attributed to all of the models not capturing the density gradients near the EIA. All of the models underestimated the topside electron density and thus also the ionospheric slab thickness. Since ionospheric models are often validated using near vertical TEC measurements and the vertical TEC is the product of the electron density at the F-region peak and the slab thickness, our results suggest that the peak density values in the models may be too high.
Print ISSN:
0048-6604
Electronic ISSN:
1944-799X
Topics:
Geosciences
,
Physics
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