Centennial to multidecadal scales variability of East Asian summer monsoon precipitation in North China during the Holocene

Abstract

Understanding the variability and forcing mechanisms of the East Asian summer monsoon (EASM) precipitation on different timescales is critically important given its potentially adverse influence on ecosystems and economic development in North China. We present a pollen-based, well-dated, ∼10 yr resolution quantitative precipitation reconstruction from an alpine lake in North China, which provides a detailed picture of EASM evolution during the past ∼11,860 years. Based on ensemble empirical mode decomposition (EEMD) method and spectral analysis, we have revealed the centennial to multidecadal scales variability of EASM precipitation and its possible driving mechanisms during the Holocene. Our results suggest that the mean annual precipitation (MAP) varied greatly during the Holocene, with the maximum precipitation (520 mm) occurring during 9500–5020 cal. yr BP, which was ∼20 % higher than present. On the centennial scale, EASM precipitation exhibited ∼500 yr, ∼200 yr, ∼130 yr, and ∼105 yr cycles. The amplitude of the ∼500 yr cycle varied greatly during the Holocene, being higher in the early and late Holocene and lower in the middle Holocene, which was possibly linked to changes in ocean circulation induced by freshwater influx to the North Atlantic. On the multidecadal scale, the EASM precipitation was dominated by a 70–90 yr cycle, which may be related to the solar activity cycle and ocean-atmosphere interactions at both high and low latitudes. Weaker (stronger) solar activity, combined with stronger El Niño-Southern Oscillation (ENSO) during the warm phase of the Pacific Interdecadal Oscillation (PDO) and a negative phase of the Atlantic Multidecadal Oscillation (AMO), caused lower (higher) sea surface temperatures (SSTs) in the Indo-West Pacific Warm Pool (IWPWP) region, resulted in weaker (stronger) EASM circulation and decreased (increased) precipitation in North China. Our findings provide significant enlightenment for distinguishing the contribution of natural factors to the changes in EASM precipitation under future global warming scenarios.