Example of determining the streamer wave properties. Panel a shows a simulation snapshot of the logarithmic density, depicting the streamer wave event B1T1.50. Green and light-blue lines show the slits along which the time–distance maps were constructed to determine the streamer wave properties. The colour scale in (a) corresponds to the logarithmic density. Panel b shows the time–distance map along the green slit in panel a. The black arrow in panel b indicates the half period measurement for the variant B1T1.50 (168 min). The colour scale in (b) corresponds to the logarithmic density. Panel c shows the time–distance map along the light-blue slit in panel a. The blue line is the linear fit corresponding to the phase speed (392 km s⁻¹). The colour scale in (c) corresponds to the θ-velocity.