Solitary structures associated with short large‐amplitude magnetic structures (SLAMS) upstream of the Earth's quasi‐parallel bow shock

For the first time, solitary waves (SWs) have been observed within short large‐amplitude magnetic structures (SLAMS) upstream of the Earth's quasi‐parallel bow shock. The SWs often occur as bipolar pulses in the electric field data and move parallel to the background magnetic field at velocities of v = 400–1200 km/s. They have peak‐to‐peak amplitudes in the parallel electric field of up to E′∥ = 65 mV/m and parallel scale sizes of L∥ ∼ 10 λD. The bipolar solitary waves exhibit negative potential structures of ∣Φ∥∣ = 0.4–2.2 V, i.e., eΦ∥/kTe ∼ 0.1. None of the theories commonly used to describe SWs adequately address these negative potential structures moving at velocities above the ion thermal speed in a weakly magnetized plasma.