Abstract
Abstract. The dominant modes of variability of precipitation for the whole of China over the past millennium and the mechanism governing their spatial structure remain unclear. This is mainly due to insufficient high-resolution proxy records of precipitation in western China. Numerous tree-ring chronologies have recently been archived in publicly available databases through PAGES2k activities, and these provide an opportunity to refine precipitation field reconstructions for China. Based on 479 proxy records, including 371 tree-ring width chronologies, a tree-ring isotope chronology, and 107 drought/flood indices, we reconstruct the precipitation field for China for the past half millennium using the optimal information extraction method. A total of 3631 of 4189 grid points in the reconstruction field passed the cross-validation process, accounting for 86.68 % of the total number of grid points. The first leading mode of variability of the reconstruction shows coherent variations over most of China. The second mode is a north–south dipole in eastern China characterized by variations of the same sign in western China and northern China (except for Xinjiang province). It is likely controlled by the El Niño–Southern Oscillation (ENSO) variability. The third mode is a sandwich triple mode in eastern China including variations of the same sign in western China and central China. The last two modes are reproduced by most of the six coupled climate models' last millennium simulations performed in the framework of the Paleoclimate Modelling Intercomparison Project Phase III (PMIP3). In particular, the link of the second mode with ENSO is confirmed by the models. However, there is a mismatch between models and proxy reconstructions in the time development of different modes. This mismatch suggests the important role of internal variability in the reconstructed precipitation mode variations of the past 500 years.
Highlights
High-resolution regional paleoclimate field reconstructions are able to accurately reproduce the fine spatiotemporal structure of regional climate change on multiple timescales for the period prior to instrumental records
The initial minimum number of predictors is five. 2599 grid points with five candidate proxy records account for 62.04 % of the total number of grid points. 3760 grid points with ≤ 10 candidate proxy records account for 89.76 %
The results show a similar pattern with a north–south dipole mode in eastern China, and the precipitation anomalies in most of western China have a positive correlation with El Niño–Southern Oscillation (ENSO) at the 90 % confidence level
Summary
High-resolution regional paleoclimate field reconstructions are able to accurately reproduce the fine spatiotemporal structure of regional climate change on multiple timescales for the period prior to instrumental records. The PPR-based method reconstructs the target variable at each grid point using a linear regression – e.g. PCR (Cook et al, 1999), RegEM regression (Shi et al, 2015a) or the OIE method (Yang et al, 2016) – by searching adequate proxy records among the ones available near the grid point. We have incorporated additional tree-ring records from western China compared to previous studies and used the PPR-based framework with the OIE method to reconstruct the precipitation fields for China. Using this reconstruction, we explore the dominant patterns of precipitation variability before the instrumental period and discuss their possible origin
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