geomagnet — Geomagnetic helpers

The geomagnet module provides a simple interface to world wide models of the Earth magnetic field. It implements simple getter functions, field() and model(), in order to access the default geomagnetic model. For test purpose alternative models can also be instanciated as Geomagnet object.

Warning

The input coordinates to the field() function or method must be a grand frame, i.e. ECEF or LTP. In addition, if no observation time is specified a default value is used (31 December 2019).

Note

The field() function and method accept vectorized input. The frame of the returned value depends on the input size. If a single point is provided the magnetic field is returned in local LTP coordinates, centered on the input coordinates. Otherwise the components are given in ECEF.

Default interface

grand.geomagnet.field(coordinates: Union[ECEF, LTP]) → Union[ECEF, LTP]

Get the default geo-magnetic field at the given coordinates.

For example, the following returns the Earth magnetic field at sea level, close to Clermont-Ferrand, France, for new year 2019.

>>> coordinates = ECEF(representation_type='geodetic', latitude=45 * u.deg,
...                    longitude=3 * u.deg, obstime='2019-01-01')
>>> field = geomagnet.field(coordinates)

property geomagnet.model

str(object=’’) -> str str(bytes_or_buffer[, encoding[, errors]]) -> str

Create a new string object from the given object. If encoding or errors is specified, then the object must expose a data buffer that will be decoded using the given encoding and error handler. Otherwise, returns the result of object.__str__() (if defined) or repr(object). encoding defaults to sys.getdefaultencoding(). errors defaults to ‘strict’.

The default geomagnetic model, i.e. IGRF12.

property geomagnet.obstime

Return date object with same year, month and day.

The deault observation time, i.e. 31 December 2019.

Alternative magnetic models

Warning

In order to get the geomagnetic field from the default GRAND model (IGRF12), one should not directly instantiate a Geomagnet object. Instead one should use the field() function of the geomagnet module. This class is only meant to be used for studies of the impact of alternative models.

Supported models for the Earth magnetic field are: IGRF12 and WMM2015.

class grand.geomagnet.Geomagnet(model: Optional[str] = None)

Proxy to a geomagnetic model

The default model is IGRF12. You can instanciate an alternative model by specifying its name, E.g. as follow:

>>> magnet = geomagnet.Geomagnet('WWM2015')

field(coordinates: Union[ECEF, LTP]) → Union[ECEF, LTP]

Get the geo-magnetic field components