Figure 3. Observed interannual variability of (a) DMI (blue) and BDI (green) during 1997-2020 and observed (b) correlation between DMI and BDI during 1997-2020 for September to October. (c) and (d), same as (a) and (b), respectively, but for GFDL-ESM4 model during 1850-2014. The regressed line is shown in red, and the correlation (r) shown in the plot is significant at the 99% confidence level. In (b), September and October months of 2016 extreme negative IOD event are marked using green labels.