The left panels show the phase-speed filtering components of panel (b) in Figure 8. The middle and right panels display the frequency-filtering components based on the corresponding left panels with P = 2.2–2.6 minutes and P = 4.2–5.7 minutes, respectively. The dotted lines mark the boundaries of LB 1. The contours in panel (e) denote a level of 25% of the maximum.