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RADIO SCIENCE, VOL. 39, RS1S14, doi:10.1029/2002RS002823, 2004

Are models predicting a realistic picture of vertical total electron content?

P. Coïsson

Abdus Salam International Centre for Theoretical Physics, Trieste, Italy


S. M. Radicella

Abdus Salam International Centre for Theoretical Physics, Trieste, Italy


R. Leitinger

Institut fuer Geophysik, Astrophysik und Meteorologie, Universitaet Graz, Graz, Austria


L. Ciraolo

Istituto di Fisica Applicata Carrara, Consiglio Nazionale delle Ricerche, Firenze, Italy


Abstract

The present work analyzes results coming from global maps of ionospheric total electron content (TEC) obtained from observations and from different empirical models like the International Reference Ionosphere (IRI), the model family developed at Trieste and Graz (NeQuick, COSTprof, and NeUoG-plas), and the GPS operational model (formulation by J. A. Klobuchar). Since they still appear in the context of assessment studies we have also included “old” models like the Bent model. The attention is focused on situations which occurred in the present period of high solar activity, pointing out features like the equatorial anomaly and polar regions, which are crucial test regions for ionospheric TEC models. Experimental estimates of slant TEC from International GPS Service (IGS) stations have been compared particularly with the predictions of the NeQuick and GPS models. A very simple picture of the ionosphere like the one given by the GPS operational model appears to be insufficient to reproduce the global complex behavior of the ionosphere, as it is needed for assessment studies or for modern operational real-time corrections of transionospheric propagation errors. The IRI estimates of TEC still present serious problems, essentially owing to the topside under high solar activity conditions, and the model cannot be integrated to heights above 2000 km. With processing resources suitable for real-time operation, it seems that the NeQuick model can give a more widely reliable picture of the TEC estimated from GPS measurements. Computing times for this model are considerably smaller than for more complex models like NeUoG-plas.

Received 13 November 2002; accepted 26 November 2003; published 5 February 2004.

Index Terms: 2415 Ionosphere: Equatorial ionosphere; 2443 Ionosphere: Midlatitude ionosphere; 2447 Ionosphere: Modeling and forecasting.

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Citation: Coïsson, P., S. M. Radicella, R. Leitinger, and L. Ciraolo (2004), Are models predicting a realistic picture of vertical total electron content?, Radio Sci., 39, RS1S14, doi:10.1029/2002RS002823.