Variability of summer precipitation over Eastern China during the last millennium

Abstract. We use measurements of recent decades, 1500-yr proxy data, and millennium model simulations with a variety of climate facings to study the temporal and spatial variability of summer precipitation over eastern China. Spectral analysis of the proxy data using multi-taper method reveals three statistically significant bidecadal (15–35-yr), pendadecadal (40–60-yr), and centennial (65–170-yr) oscillation bands. The results of wavelet filtering show that the amplitudes of these bands vary substantially through time depending on the temperature regimes. Weak centennial oscillation and strong pentadecadal oscillation occur in warm conditions, whereas both the centennial and pentadecadal oscillations are strong in cold conditions. A model/data intercomparison suggests that pentadecadal and bidecadal oscillations could be associated with internal variability of the climate system. It is also found that the increased frequency of drought-in-north/flood-in-south spatial pattern over eastern China during the last two decades is unusual in the past five centuries.