a. For modelling the average characteristics of the terrestrial magnetic field and its variation according to geomagnetic and solar activity, one of the following two external magnetic field models shall be used:
¾ Alexeev et al 2001, [RN.30]
¾ Tsyganenko 1996 [RN.31]
NOTE 1 These models are suitable for assessment of the mean and range of magnetic field strength; for estimation of B and L coordinates (but not for input to radiation belt models created with different field models); and in calculation of geomagnetic shielding of cosmic rays and solar particles.
NOTE 2 Recently, external field models have been created (e.g. Tsyganenko 2001 [RD.98], 2004 [RD.99]) that are used in research environments for dynamic modelling of field variations, e.g. substorm development. These have the capacity to represent more accurately the instantaneous magnetic field, but are not given here as standards because the definition of inputs to the models is not reasonably achievable in an engineering environment.