The Utah State University (USU) Global Assimilation of Ionospheric Measurements – Gauss Markov (GAIM-GM) model has been used to investigate the distribution of ionospheric plasma during storm times over the Continental United States. Storm periods dramatically increase the affects of space weather on the ionosphere and upper atmosphere, leading to impacts on over-the-horizon radars, GPS location determination, spacecraft charging, power grid overloads, and disruption of the Federal Aviation Administration (FAA) Wide Area Augmentation System (WAAS) to name a few. Four storm periods were investigated where strong storm enhanced densities were present; two strong, October 2003 and November 2003, and two moderate, August 2010 and August 2011. It was found that a fundamental difference in the Storm Enhanced Density (SED) formation exists between the strong and moderate storms. For the strong storms, the SED was formed from the plasma in the northern equatorial anomaly crest, with the plasma in the SED channel lifting the closer it came to the high latitudes. For the moderate storms, the SED appeared to be unconnected to the northern anomaly crest but was rather produced locally in the SED channel, along with no corresponding increase in layer height associated with the SED evident in the model.



Document Type




File Format

.NC, .gim, .gps

Viewing Instructions

.nc is the extension for NetCDF format. These files contain contain metadata which aid interpretation of the data. The metadata and data can be explored using the free Panoply software tool ( The files can also be manipulated using Unidata's free netCDF tools, a set of libraries that provide interfaces in the Java, C, C++, Fortran, and Perl programming languages. The gps.tar.gz compressed folder contains the TEC files (tec*.2d) in text format. The global.tar.gz compressed folder contains the gim*.001 files in text format and the GMF* Netcdf files.)

Publication Date



NSF, Division of Atmospheric and Geospace Sciences


Utah State University

Award Number

NSF, Division of Atmospheric and Geospace Sciences 1242074; NSF, Division of Atmospheric and Geospace Sciences 1329544


See README file.

Referenced by

Gardner, L. C., Schunk, R. W., Scherliess, L., Eccles, V., Basu, S., & Valladeres, C. (2018). Modeling the Midlatitude Ionosphere Storm-Enhanced Density Distribution With a Data Assimilation Model. Space Weather, 16(10), 1539–1548.




Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.



Additional Files

readme.txt (2 kB)
MD5: 7c0d06ea36c5129d751afd96b8b692c5

gps.tar.gz (9909 kB)
MD5: 57ba342ad9da3017350fed19ce1d61d1

global.tar.gz (1186551 kB)
MD5: 339598eb7251af1d397cba9f2d13ad25