Seasonally Regionalized Interdecadal Decrease in Extreme Precipitation Over the Tropical Indo‐Western Pacific Region Around 2008/2009

Abstract Increase in extreme precipitation is expected with global warming that leads to an increase in atmospheric moisture content. Here, we present evidence for interdecadal decrease in extreme precipitation frequency and amount around 2008/2009 over the tropical Indo‐western Pacific region. The decrease is prominent over the tropical eastern Indian Ocean in boreal fall and winter and over the tropical western Pacific in boreal spring and summer. In contrast, non‐extreme precipitation shows an increase over the broad tropical eastern Indian Ocean‐western Pacific region. This change corresponds well to a decrease in the frequency of large precipitation rate and an increase in the frequency of moderate precipitation rate. The ascending motion during extreme precipitation days experienced a weakening around 2008/2009 over the tropical Indo‐western Pacific region with a spatial pattern very similar to that of extreme precipitation decrease. The frequency of strong ascending motion displays a decrease and that of weak vertical motion displays an increase in the regions of extreme precipitation decrease. The good correspondence indicates a main role of the atmospheric dynamic effect in the extreme precipitation decrease around 2008/2009 over the tropical Indo‐western Pacific region.