“…For example, during the January 2009 SSW event, observed morning-noon enhancements and afternoon decreases in the electron density at low latitudes (Chau et al, 2012) are much less pronounced or absent in model results (Goncharenko et al, 2010b, Jin et al, 2012Klimenko et al, 2015;Pedatella et al, 2016). Several studies conclude that the primary mechanism responsible for total electron content (TEC) disturbances at low latitudes during the 2009 SSW event is a perturbation of the zonal electric field (the vertical E Â B plasma drift) (Goncharenko et al, 2010a;Jin et al, 2012;Pedatella et al, 2012;Klimenko et al, 2015). Recently, several authors exploited different models and simulation techniques (e.g., assimilation of data or dynamical nudging) to reproduce the observed equatorial electromagnetic drift disturbances during the 2009 SSW event (Fuller-Rowell et al, 2011a;Jin et al, 2012;Pedatella et al, 2016).…”