The Circum-pan Pacific Magnetometer Network (CPMN) has been constructed along the 210⁰ magnetic meridian and the magnetic equator. It is now possible to investigate the global characteristics of Pi2 pulsations. In this talk we will report on a comparative study of Pi2 pulsations observed at the CPMN stations and aurora ultraviolet data obtained by the Polar satellite. It is found that Pi2 events occur just after brightenings at the auroral latitude. The one-to-one correspondence between the Pi2 pulsations and the auroral brightening is much better than that between Pi2s and substorm bay variations. These observational facts indicate that Pi2 pulsations at all latitudes are excited just after auroral brightenings which may generate an electric field variations in the nightside auroral ionosphere. The electric field variation can be transferred instantaneously to the dayside equatorial ionosphere and produce the dayside equatorial Pi2 enhancement on the ground. The high-latitude Pi2 pulsations may be excited by a ballooning instability in the inner magnetosphere, and/or by abrupt formation of field-aligned currents caused by inhomogeneities in plasma pressure and magnetic field intensity in the inner plasma sheet. The high-latitude Pi2 pulsations are excited just as a manifestation of magnetospheric-ionospheric coupling, while the substorm onset and the magnitude of the substorm must be controlled by other mechanisms.