Fig. 8: Extratropical response to precipitation anomalies at selected tropical regions.

a Map showing a difference of precipitation over the tropics between period-2 (1999–2018) and period-1 (1979–1998) during austral summer (DJF). Difference values significant at the 90% level are dotted. Regions with positive precipitation changes (except SPCZ region), used to compute the step responses are marked by magenta boxes. b–i Step response function (computed from the “linear response theory model”) for anomalous 200-hPa geopotential height, forced by area-averaged precipitation anomaly over eight boxes shown in figure (a), during austral summer of 1999–2018.