Pro-L* - A Probabilistic L* Mapping Tool for Ground Observations to the Magnetic Equator

Both ground and space observations are used extensively in the modelling of space weather related processes within the Earth's magnetosphere. A significant challenge lies in the ability to map an instrument's geographical location into the magnetosphere. In radiation belt physics modelling, radial distance is typically approximated using L*, which indicates the location of the drift paths of electrons in the equatorial plane. Global magnetic field models allow a subset of locations on the ground (mainly sub-auroral) to be mapped along field lines to a location in space and transformed into L*, provided that location maps to a closed drift path. This allows observations from ground, or low-altitude space-based platforms to be mapped into space in order to inform radiation belt modelling. Many data-based magnetic field models exist; however these models can significantly disagree on mapped L* values for a single point on the ground, during both quiet times and storms. We present a state-of-the-art probabilistic L* mapping tool, Pro-L*, which produces probability distributions for L* corresponding to a given ground location. Pro-L* has been calculated for a high resolution magnetic latitude by MLT grid in the Earth's northern hemisphere. We have developed the probabilistic model using 11 years of L* calculations for 7 popular magnetic field models. Usage of the tool is explained for both event studies and statistical models, and we demonstrate a number of potential applications. We also discuss the development of Pro-L* into a fully functioning model, and the construction of an accompanying probabilistic L* model using a space-based grid.