Small-scale and mesoscale variabilities in the electric field and particle precipitation and their impacts on joule heating

In this study, the electric field and the particle precipitation at different spatial scale sizes have been investigated by utilizing the Dynamic Explorer 2 satellite data set, focusing on conditions of moderately strong southward interplanetary magnetic field. Dynamic Explorer 2 data from the period between 1981 and 1983, from all universal times, seasons, and both hemispheres, have been processed and binned over geomagnetic latitude and local time. It is found that, as compared with the large-scale (>500 km) average electric field and particle precipitation, the variabilities (i.e., departures from the large-scale average) of electric field and particle precipitation are not negligible. Moreover, the electric field variability tends to be anticorrelated with the particle precipitation variability in the auroral regions on small scale and mesoscale (<500 km). The impacts associated with the small-scale and mesoscale electric field and particle precipitation variabilities on Joule heating have also been addressed in this study by using the Global Ionosphere and Thermosphere Model. It is found that although Joule heating can be significantly enhanced by the small-scale and mesoscale electric field variabilities (similar to 27% globally), the corresponding change in the particle precipitation tends to depress such enhancement (-5% globally), which is not negligible on the dusk side (up to -17.5% locally). It is the first time that the correlation between electric field and particle precipitation variabilities on small scale and mesoscale has been quantified. Furthermore, the impact on Joule heating associated with the correlation between the small-scale and mesoscale electric field and particle precipitation variabilities has been evaluated unprecedentedly in a general circulation model.