Increased Frequency of Consecutive Positive IOD Events Under Global Warming

Abstract

Abstract Consecutive positive Indian Ocean Dipole (pIOD) induces more severe climate impacts than a single pIOD because of multi‐year accumulation of precipitation anomalies. Using CMIP6 outputs and reanalysis data, we show that the observed increasing trend of consecutive pIOD frequency will continue in future. The simulated frequency of consecutive pIOD increases by 131.3% over 1950–2100. More than 65% pIOD will manifest as consecutive pIOD events in the second half of this century. The increase in consecutive pIOD is dominated by the rise in mixed consecutive pIOD that contains both ENSO‐pIOD and independent pIOD. Mixed consecutive pIOD that start with ENSO‐pIOD increases fastest among all types of consecutive pIOD events. The increase is contributed by three factors: higher ENSO‐pIOD frequency, weaker biennial component of ENSO forcing, and more active pIOD triggers that are independent from ENSO. Climate extremes associated with consecutive pIOD are therefore expected to occur more frequently under global warming.

Keywords

• consecutive IOD
• global warming
• Indian ocean
• ENSO
• climate change