Fig. 2: Physical pathways for a cold-polarity IPO-SST to force the SO basin-wide SST changes.
From: Competing impacts of tropical Pacific and Atlantic on Southern Ocean inter-decadal variability
a The SST (shading) and 850-hPa winds (vectors) responses to a warm-to-cold-phase switch of IPO in idealized restoring simulations. These responses are estimated by differencing annual-mean SST (850-hPa wind) changes averaged over ten years in the warm-phase IPO-SST runs from that in the counterpart cold-phase runs. b Same as in (a), but for 200-hPa geopotential height (Z200; shading) and wave activity flux (vectors) responses. c Same as in (a), but for 500-hPa geopotential height (Z500) response. d Same as in (a), but for sea-level pressure (SLP). e–h Same as in a–d, but for responses to a warm-to-cold-phase transition of PDO. Note that the zonal mean of Z200 (Z500) at each latitude in b, c and f, g has been removed to illustrate the propagation of Rossby wave trains. The magnitude of the southern annular mode (SAM) index is estimated as the difference in the normalized zonally averaged SLP anomalies between 40°S and 65°S (0.28 for -IPO and 0.25 for -PDO). Stippling and vectors are only shown over regions where the changes are statistically significant above the 95% confidence level based on a Student’s two-sided t-test.
