Fig. 4From: Occurrence characteristics and lowest speed limit of subauroral polarization stream (SAPS) observed by the SuperDARN Hokkaido East radarResult of applying several speed thresholds to 22–1 MLT data of Fig. 3. Speed thresholds are a 50 m/s, b 100 m/s, c 150 m/s, d 200 m/s, e 250 m/s, and f 300 m/s. Flows faster than the threshold are plotted as red crosses, whereas flows slower than the threshold are plotted as black squares Back to article page