Precession-induced regime shift of summer precipitation leading modes over eastern China across the last interglacial

Abstract

It was well established that the East Asian summer monsoon experienced a long-term weakening during the transition from precession minimum (Pmin) to maximum (Pmax), but how the leading monsoonal precipitation modes at interdecadal/interannual timescale superimposing on this weakening trend may vary remains unknown, owing to the dispersively distributed proxies and their coarse resolution. To address this challenge, we perform a transient global climate simulation at ∼1° resolution during 130–115 ka that encompasses the transition from Pmin (∼127 ka) to Pmax (∼116 ka). We demonstrated that the first leading mode of summer precipitation over eastern China shifted from monopole to dipole patterns during the Pmin-to-Pmax transition, with the second leading mode switching from dipole to tripole patterns. The shifts of precipitation modes were shaped by the southward shift of the regressed atmospheric circulation systems at interdecadal/interannual timescale during the Pmin-to-Pmax transition, which were further regulated by the long-term southward retreat and weakening of the East Asian summer monsoonal circulations due to decreased summer insolation. This elucidated interdecadal/interannual drought-flood variability superimposing on the long-term weakening of the East Asian summer monsoon, which may provide insight into how gradual orbital changes reorganize short-term precipitation variability and shed light on ecological civilizations over East Asia during the Pmin-to-Pmax transition.