Assimilation of ionosonde profiles into a global ionospheric model
Article first published online: 17 MAR 2011
Copyright 2011 by the American Geophysical Union.
Volume 46, Issue 2, April 2011
How to Cite
2011), Assimilation of ionosonde profiles into a global ionospheric model, Radio Sci., 46, RS2006, doi:10.1029/2010RS004457., , and (
- Issue published online: 17 MAR 2011
- Article first published online: 17 MAR 2011
- Manuscript Accepted: 7 JAN 2011
- Manuscript Revised: 22 NOV 2010
- Manuscript Received: 11 JUN 2010
 The Utah State University Global Assimilation of Ionospheric Measurements (GAIM) ionospheric model has been run for multiday intervals in November 2008 and February/March 2009, to investigate the model's ability to assimilate plasma frequency profiles provided by Digisondes. Ionosondes are currently the only type of assimilation data that can provide information on the profile below the peak of the F2 layer. Attention has been focused on the Republic of South Africa, which has four Digisondes and thus offers a unique validation environment. The model has been run for multiple assimilation data scenarios, some of which include GPS total electron content (TEC) observations, in order to provide benchmarks for testing the profile assimilation. The Hermanus Digisonde was set aside to provide the ground truth, in particular the values of foF2, hmF2, and the width of the F2 layer. The values of these characteristics were also tested at the other three ionosonde sites, since the data assimilation procedures do not usually reproduce the assimilated data exactly. It was found that assimilation of ionosonde data did not improve the accuracy of the GAIM values of foF2 at Hermanus (or Grahamstown) beyond that provided by the GPS TEC data, but these TEC-only errors were already relatively small. However, the ionosonde-only errors were smaller than the relatively large TEC-only errors for Louisvale and Madimbo. Assimilation of ionosonde data did not provide any significant increases in the accuracy of the model values of hmF2 and width of the F2 layer.