Fig. 2: Role of negative North Pacific Meridional Mode (PMM) in generating multi-year La Niña (LN).
From: Overemphasized role of preceding strong El Niño in generating multi-year La Niña events
a‒c Composite structures of anomalous sea surface temperature (SST; shading, in °C) and surface wind (vector with minimum intensity > 0.4 m s-1) during the second spring for the three LN groups: myLN_wPrSEN (a), myLN_w/oPrSEN (b), and syLN (c). The black parallelograms delineate the region where a negative PMM occurs and exerts its influence. The gray stippled areas indicate a significance level of 0.05 as determined by a two-tailed Student’s t-test. d Evolution of PMM index for the three LN groups, with shadings representing their ±1 s.d. The index is smoothed with a 3-month running-mean filter. e Intensities of the second spring PMM index for the three LN groups, with error bars indicating their ±1 s.d. f Same as Fig. 1b, except using the ocean heat content (OHC) index values during the first fall (x-axis) plotted against the PMM index during the second spring (y-axis).
