The six W T C heatmaps are arranged in 3 rows and 2 columns. Each x-axis spans about 1980 to 2020, with labelled ticks at 1980, 1990, 2000, 2010, and 2020. Each y-axis is Period, extending from shorter periods at the top to longer periods at the bottom, with labelled ticks at 4 and 8. Each panel has a scale from 0 to 1 in increments of 0.1. Curved boundaries form broad V shaped regions, and numerous directional arrows appear across the panels. W T C N A R minus C L T contains several outlined regions, including a broad area from the early 1990s to about 2014 across periods roughly 2 to 7, with smaller outlined areas before 1990. W T C N A R minus E C I contains a compact outlined region around 1996 to 2006 near periods 4 to 5, plus outlined areas near the lower centre and outer edges. W T C N A R minus A N S contains a broad outlined region from about 1988 to 2009 across periods approximately 5 to 8, with another compact region around 2008 to 2012 near periods 2 to 4. W T C C L T minus E C I contains outlined regions around 1995 to 2010 near periods 3 to 5 and about 1993 to 2008 near periods 6 to 8, plus smaller regions near the upper edges. W T C C L T minus A N S contains outlined regions near 1983 to 1990, around 2005 to 2014 near periods 1 to 3, and about 1996 to 2012 near periods 5 to 7. W T C A N S minus E C I contains a central outlined region around 1997 to 2008 near periods 5 to 6, with smaller outlined regions along the left and right edges.Wavelet coherence between NARs, CLT, ECI and NAS
Note(s): The bold, dark outline represents the 5% significance level derived from Monte Carlo simulations. This was achieved by using phase-randomized surrogate series. In addition, the cone of influence (COI), which accounts for potential distortions due to edge effects, is depicted as a faint shadow. The colour scheme used to indicate power levels ranges from blue (indicating low power) to red (indicating high power). The arrows on the graph represent the phase difference between two time series. When the arrows point to the right, it signifies that the variables are in phase, indicating a positive relationship. Conversely, when the arrows point to the left, it suggests that the variables are out of phase, signifying a negative relationship. When the arrows are oriented to the left and upward ↖, it indicates that variable X is leading. Conversely, when the arrows point to the left and downward ↙, it suggests that variable Y is leading. On the other hand, when the arrows are oriented to the right and downward ↘, it indicates that variable X is leading. Otherwise, if the arrows are pointed to the right and upward ↗, it signifies that variable Y is leading. The x-axis represents the time period under study, while the y-axis illustrates the frequency in days. The red colour shows high correlation (coherence), while the blue colour shows low correlation (coherence)