Precipitation at Lake Qinghai, NE Qinghai-Tibet Plateau, and its relation to Asian summer monsoons on decadal/interdecadal scales during the past 500 years

Knowledge of the variability of precipitation at Lake Qinghai and its relation to the Asian summer monsoons is helpful in constraining global climatic dynamics. Based on the high-resolution precipitation indicators of δ¹³C of the organic matter (δ¹³C_org), C/N atomic ratio, and the detrended total organic carbon content (TOC_detrended), we found that the trend of precipitation at Lake Qinghai is inversely correlated to that of the Indian Summer Monsoon (ISM) inferred from layer thickness of a stalagmite (S3) in southern Oman on decadal/interdecadal scales. The Chinese Drought/Flood (D/F) indices, which can indicate the dryness/wetness over large geographic areas, are also used to indicate the intensity of the monsoon rainfall. The D/F index of Xining near Lake Qinghai is synchronous with those of the regions in northern China where the East Asian Summer Monsoon (EASM) dominates; while it is anti-phase with those of southwestern China where ISM prevails. These materials suggest that, during the past 500 years, the source of moisture to Lake Qinghai on decadal/interdecadal scales is controlled mainly by the EASM, but not by the ISM. It is also suggested that the intensity of EASM is inversely related to that of the ISM on decadal/interdecadal scales. The decadal/interdecadal variability of ENSO may be responsible for the inverse relationship between the intensity of EASM and that of ISM.