The SML index with solar wind component removed (SML − SML(ε)) to highlight potential substorm conditions during Interval 1 and Interval 2, on 7–8 September 2017. Substorm phases are identified using the gradient of a 30-min sliding box-car window, which is colour-coded by red intervals to indicate expansion phases, and blue intervals to indicate recovery phases. The times of large dH/dt events, (a)–(f), are indicated.