Boundary Models

Another option for providing boundaries are model specifications. Several empirically derived mathematical models are included in ocbpy.boundaries.models to allow access to these formulations. These models typically depend on magnetic local time (MLT) and a geomagnetic or solar wind index. OCBpy requires that these functions provide the boundary location in co-latitude (degrees of magnetic latitude away from the pole), have MLT as the first input argument, and that all other inputs be keyword arguments.

Starkov

The Starkov 1994 model (see Starkov Model) uses a mathematical formulation based on All-Sky Imager data and the Auroral Electrojet Lower envelope index. They specify three boundaries: the polar edge of the auroral oval, the equatorward edge of the auroral oval, and the equatorward edge of the diffuse aurora (usually more equatorward than the discrete edge). These may be accessed in the code here using the boundary keyworkds: ‘ocb’, ‘eab’, and ‘diffuse’, respectively.

Boundary Models Module

Functions that provide boundary locations through a mathematical model.

References

[8] (1,2)

Starkov, G. V. (1994) Mathematical model of the auroral boundaries, Geomagnetism and Aeronomy, English Translation, 34(3), 331-336.

ocbpy.boundaries.models.starkov_auroral_boundary(mlt, al=-1, bnd='ocb')

Calculate the location of the auroral boundaries.

Parameters:

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

• al (float or int) – AL geomagnetic index, Auroral Electrojet Lower envelope in nT (default=-1)

• bnd (str) – Boundary to calculate, expects one of ‘ocb’, ‘eab’, or ‘diffuse’ (default=’ocb’)

Returns:

bnd_lat – Location of the boundary in degrees away from the pole in corrected geomagnetic coordinates for the specified magnetic local times.

Return type:

float or array-like

References

[8]

ocbpy.boundaries.models.starkov_coefficient_values(al, coeff_name, bnd)

Calculate the Starkov auroral model coefficient values.

Parameters:

• al (float or int) – AL geomagnetic index, Auroral Electrojet Lower envelope in nT

• coeff_name (str) – Coefficient name, expects one of ‘A0’, ‘A1’, ‘A2’, ‘A3’, ‘alpha1’, ‘alpha2’, or ‘alpha3’

• bnd (str) – Boundary to calculate, expects one of ‘ocb’, ‘eab’, or ‘diffuse’

Returns:

coeff – Coefficient value in hours (alpha) or degrees latitude (A)

Return type:

float

References

[8]