Millennial and suborbital-scale El Nino/Southern Oscillation control of climate variability in southern China over the past 70 ka

Hydroclimatic changes in East Asia on suborbital and millennial time scales have been shown to be highly uncertain. The El Nin similar to o-Southern Oscillation (ENSO) activity plays a key role in precipitation in low-latitude East Asia on interannual and interdecadal time scales. However, there remained some ambiguity about their connection on millennial and suborbital time scales. This study comprehensively explored the multifaceted relationships between ENSO activities, suborbital and millennial-scale drought events, and hydroclimatic variations within the Huguangyan Maar Lake (HML) region during the past 70 ka. Four suborbital-scale dry and wet hydroclimatic phases interspersed with ten millennial-scale extreme dry intervals were revealed by the ratio of hematite and goethite (Hem/Goe). These stages and intervals unexpectedly coupled with the zonal sea surface temperature (Delta SST) of the tropical Pacific Ocean, underscored the complex spatial and temporal dynamics of ENSO impacts. We propose the "glacial-El Nin similar to o-arid" and "interglacial-La Nin similar to a-humid" hydroclimate patterns on the suborbital scale. While on the millennial-scale, La Nin similar to a-like fluctuations during the persistent cold period (16-40 ka) increased the frequency and intensity of droughts in low-latitude East Asia, which was in stark contrast to the wet climate in northern China. The dynamic relationship underpins a millennia-spanning La Nin similar to adrought pattern, elucidating the intertwined nature of ENSO dynamics and hydroclimatic variability on both suborbital and millennial scales. The above findings can be attributed to changes in the location and intensity of the Western Pacific subtropical high (WPSH) over southern China induced by persistent mean ENSO-like states in the tropical Pacific. This also indicates that the hydroclimate in low-latitude East Asia is more sensitive to variations in tropical ENSO compared to northern China.