Table 2 Categories of mid-latitude irregularities with respect to the Equatorward Precipitation Boundary (EPB)
From: Review of the accomplishments of mid-latitude Super Dual Auroral Radar Network (SuperDARN) HF radars
| Â | Location in relation to the EPB | Occurrence/properties |
|---|---|---|
Auroral irregularities | Poleward of the EPB | Observed at nearer ranges during storms, high-speed flow (~ 100s m s−1) |
SAPS irregularities | On the equatorward side of the EPB and usually extending only a few degrees in latitude | Occurrence increases with disturbance level; westward, high-speed flow (~ 100s m s−1) in the pre-midnight sector |
Sub-auroral irregularities | Extending equatorward of the EPB indefinitely | Nightside, low-speed flow (~10s m s−1), predominantly westward |
Temperate mid-latitude irregularities | Equatorward of the EPB by more than 10° | Strong association with MSTIDs |