spacepy.irbempy.get_Lm(ticks, loci, alpha, extMag='T01STORM', intMag='IGRF', IGRFset=0, omnivals=None)[source]

Return the MacIlwain L value for a given location, time and model

- ticks (Ticktock class)containing time information
- loci (Coords class)containing spatial information
- alpha (list or ndarray)pitch angles in degrees
- extMag (string)optional; will choose the external magnetic field model

possible values [‘0’, ‘MEAD’, ‘T87SHORT’, ‘T87LONG’, ‘T89’, ‘OPQUIET’, ‘OPDYN’, ‘T96’, ‘OSTA’, ‘T01QUIET’, ‘T01STORM’, ‘T05’, ‘ALEX’, ‘TS07’]

- intMag (string)optional: select the internal field model

possible values [‘IGRF’,’EDIP’,’JC’,’GSFC’,’DUN’,’CDIP’] For full details see get_Lstar

- omni values as dictionary (optional)if not provided, will use lookup table
- results (dictionary)containing keys: Lm, Bmin, Blocal (or Bmirr), Xj, MLT

if pitch angles provided in “alpha” then drift shells are calculated and “Bmirr” is returned if not provided, then “Blocal” at spacecraft is returned. A negative value for Lm indicates the field line is closed but particles are lost to the atmosphere; the absolute value indicates the L value.