Top panel shows time series of proton density n _p , magnetic field B, and absolute solar wind speed measured by ACE, bottom panel shows magnetic northward component residuals for magnetometer stations Abisko, Lerwick, Furstenfeldbruck, and Ascension Island, black and red vertical dashed line indicate the interplanetary shock at ACE time 2000/07/19 14:48:35 and a sudden commencement in Earth’s magnetosphere at 15:27:00 resulting in a delay of 38 min.