If you are a user of the International Reference Ionosphere (IRI) and use the daily updated index files provided by the University of New Brunswick and the IRI Working Group (https://chain-new.chain-project.net/echaim_downloads/ig_rz.dat and https://chain-new.chain-project.net/echaim_downloads/apf107.dat), please be aware that a hardcoded limit in versions of the IRI from before December 2023 will result in the model crashing if used with the provided updated index files after October 31st. We encourage all users of the IRI to update to the latest version of the model to avoid interuption and to ensure continued use of the model after October 2024.

If you use an older version of the IRI, a truncated index file is provided here: https://chain-new.chain-project.net/echaim_downloads/capped/ig_rz.dat This file will not include dates after October 2024, as such older versions of the IRI will not crash with this file, but they will not be able to be used for dates beyond October 2024.

If you use an older version of IRI2020, IRI2016, or IRI2012 but cannot update to the latest version and still need to run for dates after October 2024, a stopgap fix can be enacted as follows:

In the read_ig_rz subroutine within your version of irifun.for, replace the real variable declaration with the following:

real        aig(1600),arz(1600)

and in the tcon subroutine within your version of irifun.for, replace the real variable declaration with the following:

real        ionoindx(1600),indrz(1600)

real        ig(3),rz(3)

In versions of the IRI prior to December 2023, these variables are set to 806 elements which needs to be increased, here to 1600 elements. You should also implement a fix to the real(12,*) declarations in read_ig_rz subroutine within irifun.for with the following:

read(12,*) iupm,iupd,iupy

read(12,*) imst,iyst,imend,iyend

I do not guarantee that these changes will work for all older versions of the IRI and still recommend that all users update to the latest version, but if you recompile with these changes it should make it so that you can use those older versions of the model with the new index files.

If you use IRI2007, the ig_rz.dat file for that version is formatted differently and the new index files would not work regardless.

If you have any questions, please reach out to me or the IRI Working Group.

Cheers,

David Themens