Quantitative aspects of the Galperin L parameter

Abstract. A new geomagnetic parameter was suggested twenty years ago by Y. Galperin, the Galperin L parameter, and it was introduced into the CNES Maglib for French-Russian projects in the exploration of the distant magnetosphere. The definition and the advantages of the Galperin L parameter are recalled in this brief paper. Unforeseen possibilities in the use of this parameter for mathematical models of the magnetosphere are stressed using past results obtained with the Mead model. The Galperin L parameter is shown to add, in the synchronous region, a quantitative capability to the qualitative description (labelling) of the magnetosphere. More work will be necessary to adapt past mathematical models to present numerical models and extend the domain of the quantitative applications of the Galperin L parameter.