Reconstruction of the western Pacific warm pool SST since 1644 AD and its relation to precipitation over East China

Abstract

Based on coral proxies we reconstructed the western Pacific warm pool sea surface temperature (SST) since 1644 AD. High-frequency reconstructions are based on eight high-pass filtered coral series and raw reconstructions are derived from eight unfiltered coral series, respectively. Validation and comparison with other SST/temperature series show that the reconstructed warm pool SST is highly reliable. The leading periods of warm pool SST are ∼2.1, ∼2.3, ∼2.9, ∼3.6, ∼3.8, and 80.7-year during the last ∼360 years. The warm pool SST exhibits some obvious long-term trends: an upward trend of 0.04°C per century for the period of 1644–1825, while a decreasing trend of 0.24°C per century for the period of 1826–1885, and then a remarkable warming trend of 0.28°C per century taking place between 1886 and 2006. Especially, the SST shows the strongest trend of 0.67°C increase per century during the last 50 years, a warming unprecedented since 1644 AD. On interannual timescale, the connections between ENSO and the warm pool SST are robust during the reconstruction period. There are significant correlations between the warm pool SST and summer precipitation of the Yellow River basin and Huaihe River basin; the correlation coefficients are −0.44 in reconstruction period (1880–1949 AD) and −0.46 in instrumental period (1950–2005 AD) respectively. This relationship is also found between flood-drought index and the warm pool SST during the past 360 years, and their correlation coefficients are −0.20 in reconstruction period and −0.46 in instrumental period respectively, significant at the 0.01 level. On interdecadal timescale, this connection is more robust, and the correlation coefficient of the low-pass filtered components is −0.42 during the whole period (1644–2000 AD). When the warm pool is warmer than normal, the precipitation is usually below the normal in the Yellow River and Huaihe River basin. On the contrary, when the warm pool is colder than the normal, there may be more precipitation. The reconstructed warm pool SSTs provide useful information and reference for further research on climate change mechanism in East China.