The oscillating fringe and paleo-intensity of the East Asian monsoon reconstructed using closed-basin lake-area and dDwax
The magnitude, rate and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. In the talk, I will present the first of its kind rainfall reconstruction based on the surface area of a closed basin lake located at the modern northwestern boundary of the EAM. The results will be used to quantify the magnitude and extent of past EAM fluctuations. In addition, we constructed a compound specific hydrogen isotopes (dDwax) record from the lake. Coupling between dDwax and the lake-area reconstruction provide an opportunity to test the relation between rainfall amount and the isotopic composition of precipitation throughout the last deglaciation and Holocene.
The lake-level record is highly correlated with both northern and southern Chinese cave deposit records and the dDwax record from the lake. These results indicate that local rainfall amount is correlated with the intensity of the large EAM system. Resolving a current debate regarding the use of the isotopic composition of precipitation as a proxy for rainfall amount and validate the "intensity-based" interpretations of the Chinese cave deposit records. The covariation of lake level and the intensity of the EAM indicate that intensity and northward expansion of the EAM are linked and that during intense (weak) EAM periods the EAM northwestern boundary shifts northward (southward).