Modelling Dayside and Nightside Reconnection Rates for the Expanding/Contracting Polar Cap Paradigm

Abstract

Space weather can cause disturbances in Global Navigation Satellite Systems (GNSS) signals at high latitudes predominantly in the form of phase scintillations. These scintillations are mainly caused by polar cap patches, islands of elevated plasma density, being dragged across the polar cap from the dayside into the nightside auroral oval by ionospheric convection that arise due to solar wind-magnetosphere coupling. A previous model has been built on the expanding/contracting polar cap paradigm (ECPC) to estimate patch formation and propagation in order to predict scintillations in GNSS at high latitudes. The model simulates the ionospheric convection that transports the polar cap patches from the dayside to the nightside based on time series of solar wind-magnetosphere coupling at the magnetopause andin the magnetotail. In their paper, these reconnection rates were somewhat arbitrarily based on Super Dual Aurora Network (SuperDARN) estimates of the cross polar cap potential. In this study we propose and develop a statistical method to generate synthetic reconnection rates to be used in an ECPC ensemble model. The synthetic reconnection rates are generated 90 minutes ahead of time from an instantaneous IMF Bz measurement, and are based on historical values of reconnection rates derived from Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) data. The synthetic reconnection rate values are generated by sampling from gamma distributions fitted to the historical data. We find that the mean values of the synthetic reconnection rates are able to convincingly replicate the means of the actual reconnection rates.