http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:10962 Compressional magnetohydrodynamic (MHD) waves in the Pc3-4 frequency range (≃10–50 mHz) are generally believed to be generated upstream of the Earth's bow-shock in reflected proton beams. Inside the closed field-line geometry, these waves are conventionally considered to be a dayside phenomenon. However, recent studies suggest that some of the nighttime Pc4 pulsations may in fact have an upstream origin. In this letter, we report synchronous variations of the Pc3-4 spectra near post-dawn cusp and nightside plasmapause/plasmatrough as observed by HF radar and ground magnetometers. The measured Pc3-4 frequency closely follows that of the upstream waves theoretically predicted based on the dynamics of the interplanetary magnetic field, which presents the most convincing evidence to date of upstream-generated Pc3-4 waves propagating to the nightside magnetosphere in the closed field-line geometry. We conclude the letter with a brief discussion of a possible propagation scenario. 2012-06-25T06:12:59.423Z ]]>