Fig 4. Model parameter U (top panel) and relative change in model parameter (bottom panel) for the period 1985–2010, and for varying values of the sliding time window.

Similar to that of Fig 3, but for sliding time windows of 6, 8, 10, and 12 months. The relative change of U is based on the window-long period for which U was estimated. For all cases, four year-long intervals that follow two standard deviation drops in the model parameter overlap with the largest percentage drop events displayed by the vertical red lines.