Different stages of the AL finding method. Panel (A) shows the values of parameter W in longitudinal bins of 20° and temporal bins of 1 CR. The darker marker indicates a larger value of W. Panel (B) shows the Carrington phase of W vs. time after applying a 3σ high-pass filter to omit all of the bins with an insignificant value of W. Panel (C) shows the final stage of the finding method of AL. The repetition of the pattern in Carrington phases are removed and 3-CR moving average has been applied to the remaining peaks of W. The result shows the migration path of AL.