Dynamics of meso-scale electron precipitation and conductance in the nightside auroral oval

It is critically important to quantify multi-scale processes in order to understand their properties and to evaluate their roles in the M-I-T system. Although large-scale maps of convection and precipitation can specify the averaged state of the system, they far from reproducing dynamic and structured auroral forms and related convection. While statistical studies can specify occurrence probabilities of meso-scale (less than some hundreds of km) features, they suffer from statistical averaging and difficulties in resolving coherent plasma structures. In the present study, we present a new approach to obtain meso-scale electron precipitation and conductance distributions from the THEMIS all-sky imager array. This approach has an advantage of specifying precipitation/conductance over a semi-continental scale without losing spatial and temporal resolution of original imaging. We apply this method to a substorm event and show that meso-scale precipitation energy flux carries a substantial portion (20-35%) of the total energy flux. It is highly variable over a 10 min time scale due to localized and transient auroral brightening (poleward boundary intensifications and streamers) during the course of substorm. These results emphasize the importance of including meso-scale features in order to understand dynamic nature of M-I-T system responses.