Submission Notes 2019


During this project, 40 rolls of 35-mm film containing ISIS-II ionograms from the Resolute Bay ground 
station were fully digitized.  These films cover the eight storm periods listed below, including 
baseline periods before and after the storms.  Approximately 5500 topside ionograms are included in 
this digitized data, though not all were suitable for inversion.  Methods were developed to associate 
virtual range, frequency, and time values with each point in the ionogram. Geographical coordinates 
(latitude, longitude, and altitude) were then determined for the range of time values based on the 
satellite ephemeris.  This information was provided by the original WORLDMAP software, updated to 
run in the modern Linux GFORTRAN environment.


Event Year Days of Year  Max Kp  Approx. Film Ionograms
  A   1972    215-225      9              455
  B   1972    165-175      8+             560
  C   1972    300-310      8              567
  D   1972    255-265      8              414
  E   1973     75- 95      8+            1198
  F   1972    135-140      8-             375
  G   1973    100-125      8-            1307
  H   1971    135-140      7-             602


Suitable ionograms were analyzed in detail, including inversion of the X trace to obtain an electron 
density profile (EDP) by the method of Jackson [1969], updated to run in the modern Linux GFORTRAN 
environment.


Files submitted for this archive include the digitized film frames, annotated ionogram frames, and the 
Jackson inversion software inputs and outputs for the inverted ionograms.  The GFORTRAN versions of the 
original software are also included in the archive.  It should be possible for interested users to 
reproduce the EDPs and to generate alternative EDPs using different inversion options for comparison.


For further information about the data analysis and some observations about the storm-time polar topside 
ionosphere, see Sojka et al. [2018].


This work was supported by NASA awards NNH14CL84C and 80HQTR17C0023 to Space Environment 
Corporation (SEC). Data policy: ISIS-II 35mm films were made available to SEC from the film archive of 
the Communications Research Centre, Ottawa, Canada. 


J. E. Jackson (1969). The Reduction of Topside Ionograms to Electron-Density Profiles, 
Proc. IEEE, 57, 960-976. https://doi.org/10.1109/PROC.1969.7140


Sojka, J. J., Rice, D., Eccles, V., David, M., Schunk, R. W., Benson, R. F., & James, H.
G. (2018). Polar topside ionosphere during geomagnetic storms: Comparison of ISIS-II with
TDIM. Radio Science, 53, 906-920. https://doi.org/10.1029/2018RS006589