OCB Boundary Correction

Many high-latitude boundaries are related to each other. Both the poleward edge of the auroral oval and the R1/R2 current boundary have been successfully related to the OCB. If you have a data set of boundaries that can be related to the OCB, OCBpy is capable of applying this correction as a function of MLT. These corrections are applied using the rfunc and rfunc_kwargs keyword arguments in OCBoundary object. Several correction functions are provided as a part of ocbpy.ocb_correction module.

OCB Correction Module

Functions that specify the boundary location as a function of MLT.

References

[4] (1,2)

Burrell, A. G. et al.: AMPERE Polar Cap Boundaries, Ann. Geophys., 38, 481-490, doi:10.5194/angeo-38-481-2020, 2020.

[6]

Chisham, G. et al. (2022) Ionospheric Boundaries Derived from Auroral Images. JGR Space Physics, 127, 7, e2022JA030622, doi:10.1029/2022JA030622.

ocbpy.ocb_correction.circular(mlt, r_add=0.0)

Return a circular boundary correction.

Parameters:

• mlt (float or array-like) – Magnetic local time in hours (not actually used)

• r_add (float) – Offset added to default radius in degrees. Positive values shift the boundary equatorward, whilst negative values shift the boundary poleward. (default=0.0)

Returns:

r_corr – Radius correction in degrees at this MLT

Return type:

float or array-like

ocbpy.ocb_correction.elliptical(mlt, instrument='ampere', method='median')

Return the results of an elliptical correction to the data boundary.

Parameters:

• mlt (float or array-like) – Magnetic local time in hours

• instrument (str) – Data set’s instrument name (default=’ampere’)

• method (str) – Method used to calculate the elliptical correction, accepts ‘median’ or ‘gaussian’. (default=’median’)

Returns:

r_corr – Radius correction in degrees at this MLT

Return type:

float or array-like

References

Prefered AMPERE boundary correction validated in [4].

ocbpy.ocb_correction.harmonic(mlt, instrument='ampere', method='median')

Return the results of a harmonic fit correction to the data boundary.

Parameters:

• mlt (float or array-like) – Magnetic local time in hours

• instrument (str) – Data set’s instrument name (default=’ampere’)

• method (str) – Method used to determine coefficients; accepts ‘median’ or ‘gaussian’ when instrument is ‘ampere’. Otherwise, accepts ‘eab’ or ‘ocb’. (default=’median’)

Returns:

r_corr – Radius correction in degrees at this MLT

Return type:

float or array-like

References

AMPERE boundaries obtained from [4]. IMAGE boundaries obtained from [6].