OCB Gridding

OCB and dual-boundary gridding is performed by matching observations and OCBs and/or EABs in Universal Time (UT) and then normalising the AACGM magnetic coordinates of the observation to boundary coordinates. This is done by determining the observation’s location relative to the current boundary and placing it in the same location relative to a typical OCB and/or EAB. For the OCB, this defaults to 74 degrees, while for the EAB, this defaults to 64 degrees. Data matching is performed by ocbpy.cycle_boundary.match_data_ocb(). Coordinate normalisation, as well as boundary loading and data cycling is done within the appropriate boundary classes: OCBoundary, EABoundary, and DualBoundary.

For observations that depend on the cross polar cap potential, it is also important to scale the magnitude. This ensures that the magnitudes from different sized polar caps compare to the typical polar cap the OCB gridding produces. For vector data, the local polar north and east components may also change. Magnitude scaling is performed by ocbpy.ocb_scaling.normal_evar() or ocbpy.ocb_scaling.normal_curl_evar(). Vector scaling, re-orientation, and boundary coordinate normalisation are performed within the class VectorData. These classes and functions make up the ocbpy.ocb_scaling module.

Boundary Classes

Hold, manipulate, and load the OCB and EAB data.

References

[2](1, 2, 3, 4) Angeline Burrell, Christer van der Meeren, & Karl M. Laundal. (2020). aburrell/aacgmv2 (All Versions). Zenodo. doi:10.5281/zenodo.1212694.
[3](1, 2, 3) Shepherd, S. G. (2014), Altitude‐adjusted corrected geomagnetic coordinates: Definition and functional approximations, Journal of Geophysical Research: Space Physics, 119, 7501–7521, doi:10.1002/2014JA020264.
class ocbpy._boundary.DualBoundary(eab_filename='default', ocb_filename='default', eab_instrument='', ocb_instrument='', hemisphere=1, eab_lat=64.0, ocb_lat=74.0, stime=None, etime=None, eab_rfunc=None, eab_rfunc_kwargs=None, ocb_rfunc=None, ocb_rfunc_kwargs=None, eab=None, ocb=None, max_delta=60)[source]

Object containing EAB and OCB data for dual-boundary coordinates.

Parameters:
  • eab_filename (str or NoneType) – File containing the required equatorward auroral boundary data sorted by time. If NoneType, no file is loaded. If ‘default’, ocbpy.boundaries.files.get_default_file is called. (default=’default’)
  • ocb_filename (str or NoneType) – File containing the required open-closed field line boundary data sorted by time. If NoneType, no file is loaded. If ‘default’, ocbpy.boundaries.files.get_default_file is called. (default=’default’)
  • eab_instrument (str) – Instrument providing the EABoundaries. Requires ‘image’ or ‘dmsp-ssj’ if a file is provided. If using filename=’default’, also accepts ‘si12’, ‘si13’, ‘wic’, and ‘’. (default=’’)
  • ocb_instrument (str) – Instrument providing the OCBoundaries. Requires ‘image’, ‘ampere, or ‘dmsp-ssj’ if a file is provided. If using filename=’default’, also accepts ‘si12’, ‘si13’, ‘wic’, and ‘’. (default=’’)
  • hemisphere (int) – Integer (+/- 1) denoting northern/southern hemisphere (default=1)
  • eab_lat (float) – Typical EABoundary latitude in AACGM coordinates. Hemisphere will give this boundary the desired sign. (default=64.0)
  • ocb_lat (float) – Typical OCBoundary latitude in AACGM coordinates. Hemisphere will give this boundary the desired sign. (default=74.0)
  • stime (dt.datetime or NoneType) – First time to load data or beginning of file. If specifying time, be sure to start before the time of the data to allow the best match within the allowable time tolerance to be found. (default=None)
  • etime (dt.datetime or NoneType) – Last time to load data or ending of file. If specifying time, be sure to end after the last data point you wish to match to, to ensure the best match within the allowable time tolerance is made. (default=None)
  • eab_rfunc (numpy.ndarray, function, or NoneType) – EAB radius correction function. If None, will use the instrument default. Function must have AACGM MLT (in hours) as argument input. To allow the boundary shape to change with univeral time, each temporal instance may have a different function (array input). If a single function is provided, will recast as an array that specifies this function for all times. (default=None)
  • eab_rfunc_kwargs (numpy.ndarray, dict, or NoneType) – Optional keyword arguements for eab_rfunc. If None is specified, uses function defaults. If dict is specified, recasts as an array of this dict for all times. Array must be an array of dicts. (default=None)
  • ocb_rfunc (numpy.ndarray, function, or NoneType) – OCB radius correction function. If None, will use the instrument default. Function must have AACGM MLT (in hours) as argument input. To allow the boundary shape to change with univeral time, each temporal instance may have a different function (array input). If a single function is provided, will recast as an array that specifies this function for all times. (default=None)
  • ocb_rfunc_kwargs (numpy.ndarray, dict, or NoneType) – Optional keyword arguements for ocb_rfunc. If None is specified, uses function defaults. If dict is specified, recasts as an array of this dict for all times. Array must be an array of dicts. (default=None)
  • eab (ocbpy.EABoundary or NoneType) – Equatorward auroral boundary data object or None to initialize here (default=None)
  • ocb (ocbpy.OCBoundary) – Open-closed field line boundary data oject or Noneto initialize here (default=None)
  • max_delta (int) – Maximum number of seconds allowed between paired EAB and OCB records (default=60)
eab
ocb
max_delta
hemisphere
dtime

Numpy array of paired boundary datetimes

Type:numpy.ndarray
eab_ind

Numpy array of EAB indices for a good quality paired boundary

Type:numpy.ndarray
ocb_ind

Numpy array of OCB indices for a good quality paired boundary

Type:numpy.ndarray
rec_ind

Current OCB record index (default=0; initialised=-1)

Type:int
records

Maximum number of paired boundary records

Type:int
set_good_ind()[source]

Pair the good indices for the quality EABs and OCBs.

get_next_good_ind()[source]

Cycle to the the next quality paired boundary record.

normal_coord()[source]

Convert data position(s) to normalised co-ordinates relative to the OCB.

revert_coord()[source]

Convert the position of a measurement in OCB into AACGM co-ordinates.

get_aacgm_boundary_lats()[source]

Calculate the EAB and OCB latitude in AACGM coordinates.

calc_r()[source]

Calculate the scaled and unscaled radius at a normalised co-ordinates.

Raises:ValueError – Incorrect or incompatible input, mismatched hemisphere assignment
calc_r(bound_lat, bound_mlt, aacgm_mlt, r_corr, overwrite=False)[source]

Calculate the scaled and unscaled radius at a normalised co-ordinate.

Parameters:
  • bound_lat (array-like or float) – Normalised dual-boundary latitude in degrees
  • bound_mlt (array-like or float) – Normalised dual-boundary MLT in hours
  • aacgm_mlt (array-like or float) – MLT in AACGM coordinates in hours
  • r_corr (array-like or float) – OCB radial correction in degrees
  • overwrite (bool) – Overwrite previous boundary locations if this time already has calculated boundary latitudes for a different set of input longitudes (default=False).
Returns:

  • scaled_r (array-like) – Scaled radius for the region (OCB, EAB, Sub-auroral) in degrees
  • unscaled_r (array-like) – Unscaled radius for the region (OCB, EAB, Sub-auroral) in degrees
get_aacgm_boundary_lats(aacgm_mlt, rec_ind=None, overwrite=False, set_lon=True)[source]

Calculate the OCB latitude in AACGM coordinates at specified MLTs.

Parameters:
  • aacgm_mlt (int, float, or array-like) – AACGM longitude location(s) (in degrees) for which the OCB latitude will be calculated.
  • rec_ind (int, array-like, or NoneType) – Record index for which the OCB AACGM latitude will be calculated, or None to calculate all boundary locations (default=None).
  • overwrite (bool) – Overwrite previous boundary locations if this time already has calculated boundary latitudes for a different set of input longitudes (default=False).
  • set_lon (bool) – Calculate the AACGM longitude of the OCB alongside the MLT (default=True).

See also

ocbpy.OCBoundary.get_aacgm_boundary_lat()

get_next_good_ind()[source]

Cycle the boundary attributes to the next good paired index.

normal_coord(lat, lt, coords='magnetic', height=350.0, method='ALLOWTRACE', overwrite=False)[source]

Convert coordinates to be normalised relative to the EAB and OCB.

Parameters:
  • lat (float or array-like) – Input latitude (degrees), must be geographic, geodetic, or AACGMV2
  • lt (float or array-like) – Input local time (hours), must be solar or AACGMV2 magnetic
  • coords (str) – Input coordiate system. Accepts ‘magnetic’, ‘geocentric’, or ‘geodetic’ (default=’magnetic’)
  • height (float or array-like) – Height (km) at which AACGMV2 coordinates will be calculated, if geographic coordinates are provided (default=350.0)
  • method (str) – String denoting which type(s) of conversion to perform, if geographic coordinates are provided. Expects either ‘TRACE’ or ‘ALLOWTRACE’. See AACGMV2 for details [2]. (default=’ALLOWTRACE’)
  • overwrite (bool) – Allow the OCB and EAB AACGM boundary locations to be overwritten (default=False)
Returns:

  • bound_lat (float or array-like) – Magnetic latitude relative to EAB and OCB (degrees)
  • bound_mlt (float or array-like) – Magnetic local time relative to EAB and OCB (hours)
  • ocb_lat (float or array-like) – Magnetic latitude relative to only the OCB (degrees)
  • r_corr (float or array-like) – Radius correction to OCB (degrees)

Notes

Approximation - Conversion assumes a planar surface

Defines bound_mlt relative to only the OCB.

See also

aacgmv2(), ocbpy.OCBoundary.normal_coord()

rec_ind

Record index that identifies the current good EAB/OCB pair.

revert_coord(ocb_lat, ocb_mlt, r_corr=0.0, is_ocb=True, aacgm_mlt=None, coords='magnetic', height=350.0, method='ALLOWTRACE', overwrite=False)[source]

Convert from OCB or dual-boundary into AACGM co-ordinates.

Parameters:
  • ocb_lat (float or array-like) – Input OCB or dual-boundary latitude in degrees
  • ocb_mlt (float or array-like) – Input OCB/dual-boundary local time in hours
  • r_corr (float or array-like) – Input OCB radial correction in degrees, may be a function of AACGM MLT (default=0.0)
  • is_ocb (bool) – Specifies that the input of ocb_lat is in OCB coordinates if True or in dual-boundary coordinates if False. If False, aacgm_mlt must be provided (default=True)
  • aacgm_mlt (float, array-like, or NoneType) – Output AACGM MLT of the dual-boundary data, only used if is_ocb is False (default=None)
  • coords (str) – Output coordiate system. Accepts ‘magnetic’, ‘geocentric’, or ‘geodetic’ (default=’magnetic’)
  • height (float or array-like) – Geocentric height above sea level (km) at which AACGMV2 coordinates will be calculated, if geographic coordinates are desired (default=350.0)
  • method (str) – String denoting which type(s) of conversion to perform, if geographic coordinates are provided. Expects either ‘TRACE’ or ‘ALLOWTRACE’. See AACGMV2 for details [2]. (default=’ALLOWTRACE’)
  • overwrite (bool) – Allow the OCB and EAB AACGM boundary locations to be overwritten (default=False)
Returns:

  • lat (float or array-like) – latitude (degrees)
  • lt (float or array-like) – local time (hours)
Raises:

ValueError – When necessary inputs are not fully supplied

Notes

Approximation - Conversion assumes a planar surface

See also

aacgmv2(), ocbpy.OCBoundary.revert_coord()

set_good_ind(ocb_min_merit=None, ocb_max_merit=None, ocb_kwargs=None, eab_min_merit=None, eab_max_merit=None, eab_kwargs=None)[source]

Pair the good indices for the quality EABs and OCBs.

Parameters:
  • ocb_min_merit (float or NoneType) – Minimum value for the default figure of merit or None to not apply a custom minimum (default=None)
  • ocb_max_merit (float or NoneTye) – Maximum value for the default figure of merit or None to not apply a custom maximum (default=None)
  • ocb_kwargs (dict or NoneType) – Dict with optional selection criteria. The key should correspond to a data attribute and the value must be a tuple with the first value specifying ‘max’, ‘min’, ‘maxeq’, ‘mineq’, or ‘equal’ and the second value specifying the value to use in the comparison. None provides no optional selection criteria. (default=None)
  • eab_min_merit (float or NoneType) – Minimum value for the default figure of merit or None to not apply a custom minimum (default=None)
  • eab_max_merit (float or NoneTye) – Maximum value for the default figure of merit or None to not apply a custom maximum (default=None)
  • eab_kwargs (dict or NoneType) – Dict with optional selection criteria. The key should correspond to a data attribute and the value must be a tuple with the first value specifying ‘max’, ‘min’, ‘maxeq’, ‘mineq’, or ‘equal’ and the second value specifying the value to use in the comparison. None provides no optional selection criteria. (default=None)
class ocbpy._boundary.EABoundary(filename='default', instrument='', hemisphere=1, boundary_lat=64.0, stime=None, etime=None, rfunc=None, rfunc_kwargs=None)[source]

Object containing equatorward auroral boundary (EAB) data.

Parameters:
  • filename (str or NoneType) – File containing the required equatorward auroral boundary data sorted by time. If NoneType, no file is loaded. If ‘default’, ocbpy.boundaries.files.get_default_file is called. (default=’default’)
  • instrument (str) – Instrument providing the EABoundaries. Requires ‘image’ or ‘dmsp-ssj’ if a file is provided. If using filename=’default’, also accepts ‘si12’, ‘si13’, ‘wic’, and ‘’. (default=’’)
  • hemisphere (int) – Integer (+/- 1) denoting northern/southern hemisphere (default=1)
  • boundary_lat (float) – Typical EABoundary latitude in AACGM coordinates. Hemisphere will give this boundary the desired sign. (default=64.0)
  • stime (dt.datetime or NoneType) – First time to load data or beginning of file. If specifying time, be sure to start before the time of the data to allow the best match within the allowable time tolerance to be found. (default=None)
  • etime (dt.datetime or NoneType) – Last time to load data or ending of file. If specifying time, be sure to end after the last data point you wish to match to, to ensure the best match within the allowable time tolerance is made. (default=None)
  • rfunc (numpy.ndarray, function, or NoneType) – EAB radius correction function. If None, will use the instrument default. Function must have AACGM MLT (in hours) as argument input. To allow the boundary shape to change with univeral time, each temporal instance may have a different function (array input). If a single function is provided, will recast as an array that specifies this function for all times. (default=None)
  • rfunc_kwargs (numpy.ndarray, dict, or NoneType) – Optional keyword arguements for rfunc. If None is specified, uses function defaults. If dict is specified, recasts as an array of this dict for all times. Array must be an array of dicts. (default=None)

See also

ocbpy.OCBoundary

Raises:ValueError – Incorrect or incompatible input
class ocbpy._boundary.OCBoundary(filename='default', instrument='', hemisphere=1, boundary_lat=74.0, stime=None, etime=None, rfunc=None, rfunc_kwargs=None)[source]

Object containing open-closed field-line boundary (OCB) data.

Parameters:
  • filename (str or NoneType) – File containing the required open-closed boundary data sorted by time. If NoneType, no file is loaded. If ‘default’, ocbpy.boundaries.files.get_default_file is called. (default=’default’)
  • instrument (str) – Instrument providing the OCBoundaries. Requires ‘image’, ‘ampere’, or ‘dmsp-ssj’ if a file is provided. If using filename=’default’, also accepts ‘amp’, ‘si12’, ‘si13’, ‘wic’, and ‘’. (default=’’)
  • hemisphere (int) – Integer (+/- 1) denoting northern/southern hemisphere (default=1)
  • boundary_lat (float) – Typical OCBoundary latitude in AACGM coordinates. Hemisphere will give this boundary the desired sign. (default=74.0)
  • stime (dt.datetime or NoneType) – First time to load data or beginning of file. If specifying time, be sure to start before the time of the data to allow the best match within the allowable time tolerance to be found. (default=None)
  • etime (dt.datetime or NoneType) – Last time to load data or ending of file. If specifying time, be sure to end after the last data point you wish to match to, to ensure the best match within the allowable time tolerance is made. (default=None)
  • rfunc (numpy.ndarray, function, or NoneType) – OCB radius correction function. If None, will use the instrument default. Function must have AACGM MLT (in hours) as argument input. To allow the boundary shape to change with univeral time, each temporal instance may have a different function (array input). If a single function is provided, will recast as an array that specifies this function for all times. (default=None)
  • rfunc_kwargs (numpy.ndarray, dict, or NoneType) – Optional keyword arguements for rfunc. If None is specified, uses function defaults. If dict is specified, recasts as an array of this dict for all times. Array must be an array of dicts. (default=None)
records

Number of boundary records (default=0)

Type:int
rec_ind

Current boundary record index (default=0; initialised=-1)

Type:int
dtime

Numpy array of boundary datetimes (default=None)

Type:numpy.ndarray or NoneType
phi_cent

Numpy array of floats that give the angle from AACGM midnight of the boundary pole in degrees (default=None)

Type:numpy.ndarray or NoneType
r_cent

Numpy array of floats that give the AACGM co-latitude of the boundary pole in degrees (default=None)

Type:numpy.ndarray or NoneType
r

Numpy array of floats that give the radius of the boundary in degrees (default=None)

Type:numpy.ndarray or NoneType
fom

Numpy array of floats that provides a figure of merit that can be used to evaluate the quality of the boundary (default=None)

Type:numpy.ndarray or NoneType
min_fom

Minimum acceptable figure of merit for data (default=-np.inf)

Type:float
max_fom

Maximum acceptable figure of merit for data (default=np.inf)

Type:float
x, y, etc.

Numpy array of floats that hold the remaining values held in filename

Type:numpy.ndarray or NoneType
inst_defaults()[source]

Get the instrument-specific boundary file loading information.

load()[source]

Load the data from the specified boundary file.

get_next_good_ocb_ind()[source]

Cycle to the the next quality boundary record.

normal_coord()[source]

Convert data position(s) to normalised co-ordinates relative to the OCB.

revert_coord()[source]

Convert the position of a measurement in OCB into AACGM co-ordinates.

get_aacgm_boundary_lat()[source]

Calculate the OCB latitude in AACGM coordinates at specified MLTs.

Raises:ValueError – Incorrect or incompatible input
get_aacgm_boundary_lat(aacgm_mlt, rec_ind=None, overwrite=False, set_lon=True)[source]

Calculate the OCB latitude in AACGM coordinates at specified MLTs.

Parameters:
  • aacgm_mlt (int, float, or array-like) – AACGM longitude location(s) (in degrees) for which the OCB latitude will be calculated.
  • rec_ind (int, array-like, or NoneType) – Record index for which the OCB AACGM latitude will be calculated, or None to calculate all boundary locations (default=None).
  • overwrite (bool) – Overwrite previous boundary locations if this time already has calculated boundary latitudes for a different set of input longitudes (default=False).
  • set_lon (bool) – Calculate the AACGM longitude of the OCB alongside the MLT (default=True).

Notes

Updates OCBoundary object with list attributes. If no boundary value is calculated at a certain time, the list is padded with None. If a boundary latitude cannot be calculated at that time and longitude, that time and longitude is filled with NaN.

aacgm_boundary_lat contains the AACGM latitude location(s) of the OCB (in degrees) for each requested time [3].

aacgm_boundary_mlt holds the aacgm_mlt input for each requested time. The requested MLT may differ from time to time, to allow easy comparison with satellite passes [3].

aacgm_boundary_lon holds the aacgm_lon input for each requested time. This is calculated from aacgm_boundary_mlt by default [3].

If the boundary radius is not defined at all MLT (possible for poorly constrained boundaries), then MLT with multiple boundary values will only return one possible solution.

get_next_good_ocb_ind(min_merit=None, max_merit=None, **kwargs)[source]

Cycle to the the next quality OCB record.

Parameters:
  • min_merit (float or NoneType) – Minimum value for the default figure of merit or None to not apply a custom minimum (default=None)
  • max_merit (float or NoneTye) – Maximum value for the default figure of merit or None to not apply a custom maximum (default=None)
  • min_sectors (int) – Minimum number of MLT sectors required for good OCB. Deprecated, will be removed in version 0.3.1+ (default=7)
  • rcent_dev (float) –
    Maximum number of degrees between the new centre and the AACGM pole
    Deprecated, will be removed in version 0.3.1+ (default=8.0)
  • max_r (float) – Maximum radius for open-closed field line boundary in degrees. Deprecated, will be removed in version 0.3.1+ (default=23.0)
  • min_r (float) – Minimum radius for open-closed field line boundary in degrees Deprecated, will be removed in version 0.3.1+ (default=10.0)
  • kwargs (dict) – Dict with optional selection criteria. The key should correspond to a data attribute and the value must be a tuple with the first value specifying ‘max’, ‘min’, ‘maxeq’, ‘mineq’, or ‘equal’ and the second value specifying the value to use in the comparison.

Notes

Updates self.rec_ind to the index of next good OCB record or a value greater than self.records if there aren’t any more good records available after the starting point

Deprecated IMAGE FUV checks that: - more than 6 MLT boundary values have contributed to OCB circle - the OCB ‘pole’ is with 8 degrees of the AACGM pole - the OCB ‘radius’ is greater than 10 and less than 23 degrees AMPERE/DMSP-SSJ and new IMAGE FUV checks that: - the Figure of Merit is greater than or equal to the specified minimum

(min_fom) or less than or equal to the specified maximum (max_fom)
inst_defaults()[source]

Get the instrument-specific OCB file loading information.

Returns:
  • hlines (int) – Number of header lines
  • ocb_cols (str) – String containing the names for each data column
  • datetime_fmt (str) – String containing the datetime format

Notes

Updates the min_fom attribute for AMPERE and DMSP-SSJ

load(hlines=0, ocb_cols='year soy num_sectors phi_cent r_cent r a r_err fom', datetime_fmt='', stime=None, etime=None)[source]

Load the data from the specified boundary file.

Parameters:
  • ocb_cols (str) – String specifying format of OCB file. All but the first two columns must be included in the string, additional data values will be ignored. If ‘year soy’ aren’t used, expects ‘date time’ in ‘YYYY-MM-DD HH:MM:SS’ format. (default=’year soy num_sectors phi_cent r_cent r a r_err r_merit’)
  • hlines (int) – Number of header lines preceeding data in the OCB file (default=0)
  • datetime_fmt (str) – A string used to read in ‘date time’ data. Not used if ‘year soy’ is specified. (default=’’)
  • stime (dt.datetime or NoneType) – Time to start loading data or None to start at beginning of file. (default=None)
  • etime (datetime or NoneType) – Time to stop loading data or None to end at the end of the file. (default=None)
normal_coord(lat, lt, coords='magnetic', height=350.0, method='ALLOWTRACE')[source]

Convert position(s) to normalised co-ordinates relative to the OCB.

Parameters:
  • lat (float or array-like) – Input latitude (degrees), must be geographic, geodetic, or AACGMV2
  • lt (float or array-like) – Input local time (hours), must be solar or AACGMV2 magnetic
  • coords (str) – Input coordiate system. Accepts ‘magnetic’, ‘geocentric’, or ‘geodetic’ (default=’magnetic’)
  • height (float or array-like) – Height (km) at which AACGMV2 coordinates will be calculated, if geographic coordinates are provided (default=350.0)
  • method (str) – String denoting which type(s) of conversion to perform, if geographic coordinates are provided. Expects either ‘TRACE’ or ‘ALLOWTRACE’. See AACGMV2 for details [2]. (default=’ALLOWTRACE’)
Returns:

  • ocb_lat (float or array-like) – Magnetic latitude relative to OCB (degrees)
  • ocb_mlt (float or array-like) – Magnetic local time relative to OCB (hours)
  • r_corr (float or array-like) – Radius correction to OCB (degrees)

Notes

Approximation - Conversion assumes a planar surface

See also

aacgmv2()

revert_coord(ocb_lat, ocb_mlt, r_corr=0.0, coords='magnetic', height=350.0, method='ALLOWTRACE')[source]

Convert the position of a measurement in OCB into AACGM co-ordinates.

Parameters:
  • ocb_lat (float or array-like) – Input OCB latitude in degrees
  • ocb_mlt (float or array-like) – Input OCB local time in hours
  • r_corr (float or array-like) – Input OCB radial correction in degrees, may be a function of AACGM MLT (default=0.0)
  • coords (str) – Output coordiate system. Accepts ‘magnetic’, ‘geocentric’, or ‘geodetic’ (default=’magnetic’)
  • height (float or array-like) – Geocentric height above sea level (km) at which AACGMV2 coordinates will be calculated, if geographic coordinates are desired (default=350.0)
  • method (str) – String denoting which type(s) of conversion to perform, if geographic coordinates are provided. Expects either ‘TRACE’ or ‘ALLOWTRACE’. See AACGMV2 for details [2]. (default=’ALLOWTRACE’)
Returns:

  • lat (float or array-like) – latitude (degrees)
  • lt (float or array-like) – local time (hours)

Notes

Approximation - Conversion assumes a planar surface

See also

aacgmv2()

Cycle Boundary Module

Routines to match and cycle through the OCboundary class records.

ocbpy.cycle_boundary.match_data_ocb(ocb, dat_dtime, idat=0, max_tol=60, min_merit=None, max_merit=None, **kwargs)[source]

Match data records with OCB records.

Parameters:
  • ocb (ocbpy.OCBoundary, ocbpy.EABoundary, or ocbpy.DualBoundary) – Class containing the open-close field line, equatorial auroral boundary, or dual-boundary data
  • dat_dtime (list-like) – List or array of datetime objects where data exists
  • idat (int) – Current data index (default=0)
  • max_tol (int) – maximum seconds between OCB and data record in sec (default=60)
  • min_merit (float or NoneType) – Minimum value for the default figure of merit or None to not apply a custom minimum (default=None)
  • max_merit (float or NoneTye) – Maximum value for the default figure of merit or None to not apply a custom maximum (default=None)
  • kwargs (dict) – Dict with optional selection criteria. The key should correspond to a data attribute and the value must be a tuple with the first value specifying ‘max’, ‘min’, ‘maxeq’, ‘mineq’, or ‘equal’ and the second value specifying the value to use in the comparison.
  • min_sectors (int) – Minimum number of MLT sectors required for good OCB. Deprecated, will be removed in version 0.3.1+ (default=7)
  • rcent_dev (float) – Maximum number of degrees between the new centre and the AACGM pole. Deprecated, will be removed in version 0.3.1+ (default=8.0)
  • max_r (float) – Maximum radius for open-closed field line boundary in degrees Deprecated, will be removed in version 0.3.1+ (default=23.0)
  • min_r (float) – Minimum radius for open-closed field line boundary in degrees Deprecated, will be removed in version 0.3.1+ (default=10.0)
Returns:

idat – Data index for match value, None if all of the data have been searched
Return type:

int or NoneType
Raises:

ValueError – If the input boundary class has an unknown cycling method name

Notes

Updates ocb.rec_ind for matched value. This attribute is set to None if all of the boundaries have been searched.

ocbpy.cycle_boundary.retrieve_all_good_indices(ocb, min_merit=None, max_merit=None, **kwargs)[source]

Retrieve all good indices from the OCBoundary class.

Parameters:
  • ocb (ocbpy.OCBoundary or ocbpy.EABoundary) – Class containing the open-close field line or equatorward auroral boundary data
  • min_merit (float or NoneType) – Minimum value for the default figure of merit or None to not apply a custom minimum (default=None)
  • max_merit (float or NoneTye) – Maximum value for the default figure of merit or None to not apply a custom maximum (default=None)
  • kwargs (dict) – Dict with optional selection criteria. The key should correspond to a data attribute and the value must be a tuple with the first value specifying ‘max’, ‘min’, ‘maxeq’, ‘mineq’, or ‘equal’ and the second value specifying the value to use in the comparison.
Returns:

good_ind – List of indices containing good OCBs
Return type:

list
ocbpy.cycle_boundary.satellite_track(lat, mlt, x1, y1, x2, y2, hemisphere, del_x=1.0, del_y=1.0, past_bound=5.0)[source]

Determine whether or not a point lies along the satellite track.

Parameters:
  • lat (array-like) – AACGM latitude in degrees
  • mlt (array-like) – AACGM local time in hours
  • x1 (float) – Cartesian x-coordinate of the first boundary location in AACGM degrees along the Dawn-Dusk axis
  • y1 (float) – Cartesian y-coordinate of the first boundary location in AACGM degrees along the Noon-Midnight axis
  • x2 (float) – Cartesian x-coordinate of the second boundary location in AACGM degrees along the Dawn-Dusk axis
  • y2 (float) – Cartesian y-coordinate of the second boundary location in AACGM degrees along the Noon-Midnight axis
  • hemisphere (int) – Integer (+/- 1) denoting northern/southern hemisphere
  • del_x (float) – Allowable distance from the track in AACGM degrees along the x-axis (default=1.0)
  • del_y (float) – Allowable distance from the track in AACGM degrees along the y-axis (default=1.0)
  • past_bound (float) – Allowable distance equatorward from the boundary in AACGM degrees (default=5.0)
Returns:

good – Array of booleans that are True if location is along the track and False if the location falls outside of the track
Return type:

array-like
Raises:

ValueError – If the boundary values are negative or if an unknown hemisphere is specified

OCB Scaling Module

Scale data affected by magnetic field direction or electric field.

References

[1](1, 2) Chisham, G. (2017), A new methodology for the development of high-latitude ionospheric climatologies and empirical models, Journal of Geophysical Research: Space Physics, 122, doi:10.1002/2016JA023235.
class ocbpy.ocb_scaling.VectorData(dat_ind, ocb_ind, aacgm_lat, aacgm_mlt, ocb_lat=nan, ocb_mlt=nan, r_corr=nan, aacgm_n=0.0, aacgm_e=0.0, aacgm_z=0.0, aacgm_mag=nan, dat_name=None, dat_units=None, scale_func=None)[source]

Object containing a vector data.

Parameters:
  • dat_ind (int or array-like) – Data index (zero offset) for the input
  • ocb_ind (int or array-like) – OCBoundary or DualBoundary record index matched to this data index (zero offset)
  • aacgm_lat (float or array-like) – Vector AACGM latitude (degrees)
  • aacgm_mlt (float or array-like) – Vector AACGM MLT (hours)
  • ocb_lat (float or array-like) – Vector OCB latitude (degrees) (default=np.nan)
  • ocb_mlt (float or array-like) – Vector OCB MLT (hours) (default=np.nan)
  • aacgm_n (float or array-like) – AACGM North pointing vector (positive towards North) (default=0.0)
  • aacgm_e (float or array-like) – AACGM East pointing vector (completes right-handed coordinate system (default = 0.0)
  • aacgm_z (float or array-like) – AACGM Vertical pointing vector (positive down) (default=0.0)
  • aacgm_mag (float or array-like) – Vector magnitude (default=np.nan)
  • dat_name (str) – Data name (default=None)
  • dat_units (str) – Data units (default=None)
  • scale_func (function) – Function for scaling AACGM magnitude with arguements: [measurement value, mesurement AACGM latitude (degrees), mesurement OCB latitude (degrees)] (default=None)
vshape

Shape of output data

Type:array-like
unscaled_r

Radius of polar cap in degrees

Type:float or array-like
scaled_r

Radius of normalised OCB polar cap in degrees

Type:float or array-like
ocb_n

OCB north component of data vector (default=np.nan)

Type:float or array-like
ocb_e

OCB east component of data vector (default=np.nan)

Type:float or array-like
ocb_z

OCB vertical component of data vector (default=np.nan)

Type:float or array-like
ocb_mag

OCB magnitude of data vector (default=np.nan)

Type:float or array-like
ocb_quad

AACGM quadrant of OCB pole (default=0)

Type:int or array-like
vec_quad

AACGM quadrant of Vector (default=0)

Type:int or array-like
pole_angle

Angle at vector location appended by AACGM and OCB poles in degrees (default=np.nan)

Type:float or array-like
aacgm_naz

AACGM north azimuth of data vector in degrees (default=np.nan)

Type:float or array-like
ocb_aacgm_lat

AACGM latitude of OCB pole in degrees (default=np.nan)

Type:float or array-like
ocb_aacgm_mlt

AACGM MLT of OCB pole in hours (default=np.nan)

Type:float or array-like

Notes

May only handle one data type, so scale_func cannot be an array

aacgm_mag

Magntiude of the AACGM vector(s).

calc_ocb_polar_angle()[source]

Calculate the OCB north azimuth angle.

Returns:ocb_naz – Angle between measurement vector and OCB pole in degrees
Return type:float or array-like
Raises:ValueError – If the required input is undefined

Notes

Requires ocb_quad, vec_quad, aacgm_naz, and pole_angle

calc_ocb_vec_sign(north=False, east=False, quads={})[source]

Calculate the sign of the North and East components.

Parameters:
  • north (bool) – Get the sign of the north component(s) (default=False)
  • east (bool) – Get the sign of the east component(s) (default=False)
  • quads (dict) – Dictionary of boolean values or arrays of boolean values for OCB and Vector quadrants. (default=dict())
Returns:

vsigns – Dictionary with keys ‘north’ and ‘east’ containing the desired signs
Return type:

dict
Raises:

ValueError – If the required input is undefined

Notes

Requires ocb_quad, vec_quad, aacgm_naz, and pole_angle

calc_vec_pole_angle()[source]

Calc the angle between the AACGM pole, data, and the OCB pole.

Raises:ValueError – If the input is undefined or inappropriately sized arrays

Notes

Requires aacgm_mlt, aacgm_lat, ocb_aacgm_mlt, and ocb_aacgm_lat. Updates pole_angle using spherical trigonometry.

clear_data()[source]

Clear or initialize the output data attributes.

dat_ind

Data index(es).

define_quadrants()[source]

Define AACGM MLT quadrants for the OCB pole and data vector.

Notes

North (N) and East (E) are defined by the AACGM directions centred on the data vector location, assuming vertical is positive downwards Quadrants: 1 [N, E]; 2 [N, W]; 3 [S, W]; 4 [S, E]

Requires ocb_aacgm_mlt, aacgm_mlt, and pole_angle. Updates ocb_quad and vec_quad

Raises:ValueError – If the required input is undefined
ocb_ind

Boundary index(es).

ocb_lat

Boundary latitude in degrees.

ocb_mlt

Boundary magnetic local time in hours.

r_corr

Boundary radius correction in degrees.

scale_vector()[source]

Normalise a variable proportional to the curl of the electric field.

Raises:ValueError – If the required input is not defined

Notes

Requires ocb_lat, ocb_mlt, ocb_aacgm_mlt, and pole_angle. Updates ocb_n, ocb_e, ocb_z, and ocb_mag

set_ocb(ocb, scale_func=None)[source]

Set the OCBoundary values for provided data (updates all attributes).

Parameters:
  • ocb (ocbpy.OCBoundary or ocbpy.DualBoundary) – OCB, EAB, or Dual boundary object
  • scale_func (function) – Function for scaling AACGM magnitude with arguments: [measurement value, mesurement AACGM latitude (degrees), mesurement OCB latitude (degrees)] Not necessary if defined earlier or no scaling is needed. (default=None)
ocbpy.ocb_scaling.archav(hav)[source]

Calculate the inverse haversine.

Parameters:hav (float or array-like) – Haversine of an angle
Returns:alpha – Angle in radians
Return type:float or array-like

Notes

The input must be positive. However, any number with a magnitude below 10-16 will be rounded to zero. More negative numbers will return NaN.

ocbpy.ocb_scaling.hav(alpha)[source]

Calculate the haversine.

Parameters:alpha (float or array-like) – Angle in radians
Returns:hav_alpha – Haversine of alpha, equal to the square of the sine of half-alpha
Return type:float or array-like
ocbpy.ocb_scaling.normal_curl_evar(curl_evar, unscaled_r, scaled_r)[source]

Normalise a variable proportional to the curl of the electric field.

Parameters:
  • curl_evar (float or array) – Variable related to electric field (e.g. vorticity)
  • unscaled_r (float or array) – Radius of polar cap in degrees
  • scaled_r (float or array) – Radius of normalised OCB polar cap in degrees
Returns:

nvar – Normalised variable
Return type:

float or array

Notes

Assumes that the cross polar cap potential is fixed across the polar cap regardless of the radius of the Open Closed field line Boundary. This is commonly assumed when looking at statistical patterns that control the IMF (which accounts for dayside reconnection) and assume that the nightside reconnection influence is averaged out over the averaged period [1].

ocbpy.ocb_scaling.normal_evar(evar, unscaled_r, scaled_r)[source]

Normalise a variable proportional to the electric field.

Parameters:
  • evar (float or array) – Variable related to electric field (e.g. velocity)
  • unscaled_r (float or array) – Radius of polar cap in degrees
  • scaled_r (float or array) – Radius of normalised OCB polar cap in degrees
Returns:

nvar – Normalised variable
Return type:

float or array

Notes

Assumes that the cross polar cap potential is fixed across the polar cap regardless of the radius of the Open Closed field line Boundary. This is commonly assumed when looking at statistical patterns that control the IMF (which accounts for dayside reconnection) and assume that the nightside reconnection influence is averaged out over the averaged period [1].