Regional differences in summer monsoon precipitation variability reconstructed from multiple proxies in Asia during the past millennium

Rainfall in the Asia summer monsoon (ASM) domain has a complex spatial pattern with the temporal variability at different timescales and their long-term change has not been fully characterized. An updated 320 multiple proxies network is used to reconstruct the May-October precipitation during the past millennium for eight regions in the ASM domain. The spatial consistency of summer monsoon precipitation variability and the possible links to the internal climate oscillations are investigated. The results show that the regional precipitations over the last millennium in the ASM regions are dominated by the inter-annual cycle of 2-2.5a and 3.5-5a, the decadal cycle of similar to 11a and 15-25a and the multidecadal cycle of similar to 30a and 40-80a. Coherent dry decades in different regions appear in 1100-1250, 1600-1650 and 1960-2000, while the wet decades appear in 970-990, 1330-1350, 1380-1430, 1550-1580, 1700-1780 and 1810-1910. On interannual scale, the relationships between precipitation for each region and El Nino-Southern Oscillation (ENSO) in both developing and decaying stages are unstable over the entire millennium, but they have opposite-sign correlations most of the time, which implies that the summer precipitation anomaly for a region tends to reverse in the next summer when a strong ENSO event occurs in the winter. For the long-term change from multidecadal to centennial scales, the longest dry period of the 12th to 13th centuries in eastern Asia coincides with the period with the lowest ENSO variability due to the in phase change of the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation, which could result in the neutral interbasin east-west cell in Tropics and low frequency of ENSO events.