Department of Physics and Astronomy

Correction to the Cooling model code

The IDL source code for the Cooling model (Cooling et al., 2001) is available on Brigid Cooling's website, but it currently contains a bug in the function that traces the reconnection line across the magnetopause. If you initiate an X-line at the subsolar point with a strong IMF BY component, uncorrected code will produce an X-line that is straight (viewed in the X-Y plane, see below left), whereas the corrected code produces the expected 'S' shaped X-lines (below right).

[Result of uncorrected code][Result of corrected code]

The bug arises in the "mergeline" function, which traces a component reconnection line from a specified point. The routine should evaluate the local model magnetosheath and magnetospheric magnetic field directions (Bms and Bgm), calculate the direction perpendicular to the vector (Bms - Bgm), take a step in this direction to trace the X-line and repeat the process. Instead, the code evaluates Bms and Bgm at the initially-specified reconnection site and uses these parameters throughout the function (hence the straight line).

This bug only affects the tracing of the X-line, and the error is only significant for lengthy component X-lines.

Corrected code

UPDATED: 12th June 2008
Robert Fear
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