摘要：Recent imager and radar observations in the nightside polar cap have shown evidence that polar cap patches are
associated with localized flow channels. To understand how flow channels propagate from the dayside auroral oval
into the polar cap, we use an all-sky imager in Antarctica and DMSP (F13, F15, F16, F17 and F18) to determine properties of density and flows associated with dayside polar cap patches. We identified 50 conjunction events during
the southern winter seasons of 2007–2011. In a majority (45) of events, longitudinally narrow flow enhancements
directed anti-sunward are found to be collocated with the patches, have velocities (up to a few km/s) substantially
larger than the large-scale background flows (~500 m/s) and have widths comparable to patch widths (~400 km).
While the patches start with poleward moving auroral forms (PMAFs) as expected, many PMAFs propagate azimuthally away from the noon over a few hours of MLT, resulting in formation of polar cap patches quite far away from the
noon, as early as ~6 MLT. The MLT separation from the noon is found to be proportional to the IMF |By|. Fast polar cap
flows of >~1500 m/s are predominantly seen during large IMF |By| and small |Bz|. The presence of fast, anti-sunward
flow channels associated with the polar cap patches suggests that the flow channels form in the dayside auroral oval
through transient reconnection and can be the source of flow channels propagating into the polar cap.
关键词：Dayside polar cap; Airglow patches; Flow channels; AGO ASI; DMSP satellites; IMF
