Important Data Updates:
On March 27, 2017 the JB2008 indices were updated to v5.3g as part of an annual review of these indices. Included in this update are corrections to the S10 index during 2016 and 2017 resulting from calibration changes in the SDO/EVE data that are used to create S10. In addition, improvements to both the solar cycle 23 minimum (2008-2009) S10 values and the rise to solar cycle 24 maximum (2010-2014) were made. The updated indices were validated against 3 LEO debris objects whose ballistic coefficients are very well known.
To run the JB2008 model you will need the solar (SOLFSMY.TXT) and geomagnetic storm indices (SOLRESAP.TXT and DSTFILE.TXT) from the downloadable files in the Current Indices table above: the geomagnetic storm indices are generated from hourly Dst values during moderate to high geomagnetic activity, and from 3-hour ap values during low to no storm activity. Also, note that there is 45-day lag between the current Day-Of-Year and the last data DOY in the indices files.
If you desire to compute the storm indices yourself then you need to download the code file (DTCMAKEDR.for.txt, version 5.3), and edit directory/file paths. You then need to use the updated Dst values (DSTFILE.TXT) and ap values (SOLRESAP.TXT), which are updated here daily. The DTCMAKEDR.for program will then generate a new DTCFILE.TXT file. This file is the one above currently being automatically generated on this web site.
Note on the pre-2012 DTCFILE.TXT data file with a YY year format (Non-Y2K compliant):
In order to maintain compatibility with earlier versions of distributed software, the DTCFILE_YY.TXT file with the YY year format (which is not Y2K compliant) is maintained here. If used, it needs to be re-named to DTCFILE.TXT after downloading, and only used with the older ( before 2008 - 2012) Fortran programs (e.g., JB08DRV.for and DTCMAKEDR.for). Be careful not to confuse the YY-format DTCFILE_YY.TXT with the newer DTCFILE.TXT file that uses the YYYY Y2K-compliant format.
It is highly recommended that the newer Y2K-compliant DTCFILE.TXT file and code be used