Hydroclimate dipole pattern in the eastern South African monsoon domain on various timescales.

Precipitation variability in the South African Monsoon Domain, which encompasses much of southern Africa and the adjoining Indian Ocean, is marked by a distinct dipole pattern, with one center over southeastern Africa and the other along a northwest-southeast-oriented belt that extends across tropical eastern Africa and the southwest Indian Ocean. However, the climatic mechanisms of this dipole pattern over timescales remain unclear. In this study, we integrate modern observations, reanalysis data, and regional paleoclimate proxy records spanning the past 8 ka to investigate hydroclimate variability in the eastern South African Monsoon Domain at interannual to millennial scales. While modern observations identify the Indian Ocean Basin Mode (IOB), Subtropical Indian Ocean Dipole (SIOD), and Indian Ocean Dipole (IOD) as key drivers, the shift from IOD- to IOB/SIOD-dominated SSTA patterns reflects both long-term Pacific forcing and strong Indian Ocean-Pacific coupling that critically shapes rainfall variability in the South African Monsoon Domain. The SIOD and IOB dominate hydroclimate fluctuations in tropical eastern Africa and the southwest Indian Ocean, while the interaction between SIOD and El Niño Southern Oscillation amplifies the southeastern Africa - the southwest Indian Ocean dipole pattern. On longer timescales, we find that multi-millennial and multi-centennial hydroclimate precipitation patterns broadly resemble the dipole pattern as observed today. However, comparisons lack support from western Indian Ocean SST reconstructions, necessitating further high-resolution SST records and model simulations to validate these relationships.