Fig. 3: Time series of JJA-mean normalized climate mode indices based on monthly observational data with the 1961–2017 mean removed. | npj Climate and Atmospheric Science

Fig. 3: Time series of JJA-mean normalized climate mode indices based on monthly observational data with the 1961–2017 mean removed.

From: Intensification of heatwaves in China in recent decades: Roles of climate modes

Fig. 3: Time series of JJA-mean normalized climate mode indices based on monthly observational data with the 1961–2017 mean removed.The alternative text for this image may have been generated using AI.

a Nino3.4 index; b the Atlantic multidecadal oscillation (AMO) index; c the Indian Ocean Dipole Mode Index (DMI); d the detrended IPO index (black line) and AMO index (shading) from 1920 to 2017. e Spatial patterns of SST anomalies (SSTA; °C) associated with a positive IPO over the Pacific and negative AMO over the North Atlantic (color shading); f time series of 8 yr-lowpass-filtered normalized IPO and AMO indices (black and blue dotted curves), an idealized sinusoidal SSTA that mimics the IPO index (thick solid red) and AMO index but with an opposite sign, and a sinusoidal SSTA with a 2-year period representing ENSO interannual variability (thin solid red).

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