A novel technique for rapid L^* calculation: Algorithm and implementation

Computing the magnetic drift invariant, L^*, rapidly and accurately has always been a challenge to magnetospheric modelers, especially given the importance of this quantity in the radiation belt community. Min et al. (2013) proposed a new method of calculating L^* using the principle of energy conservation. Continuing with the approach outlined therein, the present paper focuses on the technical details of the algorithm to outline the implementation, systematic analysis of accuracy, and verification of the speed of the new method. We also show new improvements which enable near real-time computation of L^*. The relative error is on the order of 10^-3 when ∼0.1 R_E grid resolution is used and the calculation speed is about 2 s per particle in the popular Tsyganenko and Sitnov 05 model (TS05). Based on the application examples, we suggest that this method could be an added resource for the radiation belt community. Key PointsNew, efficient method of L* calculationFast, accurate calculation using first principlesHighly scalable to a large number of L* values at reducing incremental cost