# Software Archive

Publically available software.

## Altitude Adjusted Corrected Geogmagnetic Coordinates

Altitude adjusted corrected geomagnetic (AACGM) coordinates are an extension of corrected geomagnetic (CGM) coordinates that more accurately represent the actual magnetic field. In AACGM coordinates points along a given magnetic field line are given the same coordinates and thus are a better reflection of magnetic conjugacy.

The coordinate system was originally defined by *Baker and Wing* [1989]
in order to compare conjugacy of data from SuperDARN radars located in
Goose Bay, Labrador and Halley Bay, Antarctica. Subsequent updates to the
technique focused on the equatorial region and the south Atlantic anomaly
*Bhavnani and Hein*, 1994; *Hein and Bhavnani*, 1996; *Heres
and Bonito*, 2007].

The software available here uses a new set of AACGM coefficients that more
accurately represent the AACGM coordinates [*Shepherd*, 2014]. It is
provided without warranty.

### AACGM Coefficients

Version |
Release Date |

aacgm_coeffs-leo-11.tar | June 1, 2014 |

### IDL Software

Version |
Release |
Description |

v0.3 | 20140702 | tar file that contains only the software, a test program and a README file. You must set an environment variable to run this software, see README. The field line tracing options for this release are still not as reliable as I would like. Please take extra care using these options. |

v0.2 |
20140618 | tar file that contains all coefficients, software, a test program and a README file. |

v0.1 |
20140527 | initial release |

### C Software

Version |
Release |
Description |

v0.2 | 20140707 | Minor changes. |

v0.1 |
20140702 | tar file that contains only the software, a test program and a README file. You must set an environment variable to run this software, see README. Field line tracing options are not yet implemented in C. The maximum altitude is therefore limited to 2000 km. |

### General Notes

The latest coefficients (2015) are derived using secular variation of the
IGRF-11 model.

Please send questions, comments and bugs to simon *dot* shepherd
*at* dartmouth *dot* edu.

### References

Baker, K. B. and S. Wing (1989), A new magnetic coordinate system for
conjugate studies at high latitudes, *J. Geophys. Res., 94*(a7),
p. 9139, doi:10.1029/JA094iA07p09139.

Bhavnani, K. H. and C. A. Hein (1994), An improved algorithm for computing altitude dependent corrected geomagnetic coordinates, Phillips Lab., Geophys. Dir., Hanscom Air Force Base, Mass., PL-TR-94-2310.

Hein, C. A. and K. H. Bhavnani (1996), An expanded altitude algorithm for computing altitude-dependent corrected geomagnetic coordinates, Phillips Lab., Geophys. Dir., Hanscom Air Force Base, Mass., PL-TR-96-2274.

Heres, W. and N. A. Bonito (2007), An alternative method of computing altitude adjustment [sic] corrected geomagnetic coordinates as applied to IGRF Epoch 2005, Air Force Research Lab., Space Vehicles Dir., Hanscom Air Force Base, Mass., HA-TR-2007-1190.

Shepherd, S. G. (2014), Altitude-adjusted corrected geomagnetic coordinates:
Definition and functional approximations, *submitted to J. Geophys. Res.
* preprint (note that figure numbers
may not have been processed correctly.)