Deglacial variability of South China hydroclimate heavily contributed by autumn rainfall

A recent hydroclimate proxy suggests that South China became wet in cold stadials during the last deglaciation, with the intensification proposed to be contributed mostly by the East Asian summer monsoon (EASM). Here, based on a deglacial simulation in a state-of-the-art climate model that well reproduces the evolution of EASM, winter monsoon (EAWM) and the associated water isotopes in East Asia, we propose that the intensified hydroclimate in South China is also contributed heavily by the rainfall in autumn, during the transition between EASM and EAWM.

The excessive rainfall in autumn results from the convergence between anomalous northerly wind due to amplified land-sea thermal contrast and anomalous southerly wind associated with the anticyclone over Western North Pacific, both of which are, in turn, forced by the slowdown of the Atlantic thermohaline circulation. Regardless the rainfall change, however, the modeled delta O-18(p) remains largely unchanged in autumn.