中国南方降水δ^(18)O年际变化响应ENSO机理的再分析

Reanalysis of interannual variability of precipitation δ^(18)O in southern China in response to ENSO

中国南方石笋δ^(18)O记录已成为重建过去季风变化历史的重要载体,然而对石笋δ^(18)O记录的气候解译目前仍存在争议。本文基于模拟数据和气象观测数据建立了1979-2016年中国南方16个主要城市的降水δ^(18)O年际变化序列,并利用主成分分析方法提取了这些δ^(18)O序列的第一主成分。该主成分序列与海洋尼诺指数总体上呈现出显著正相关,表明厄尔尼诺-南方涛动(ENSO)对中国南方降水δ^(18)O年际变化具有显著影响。进一步分析表明,ENSO主要通过控制孟加拉湾和南海等水汽上游地区对流强度和西太平洋副热带高压强度来对中国南方降水δ^(18)O施加影响,但水汽上游地区对流强度的作用可能更强。此外,降水δ^(18)O与ENSO在不同时段的相关性并非稳定,这可能影响石笋δ^(18)O对ENSO历史重建的准确性。

Oxygen isotope records(δ^(18)O)obtained from stalagmites in southern China are valuable proxy data for paleomonsoon reconstruction.However,the interpretation of the stalagmiteδ^(18)O records remains an ongoing de⁃bate.Based on simulation data and meteorological observation data,we present the interannual variability of pre⁃cipitationδ^(18)O series of 16 major cities in southern China from 1979 to 2016 and extract the first principal compo⁃nent(PC1)of theseδ^(18)O series by using principal component analysis.Overall,the PC1 shows a significantly posi⁃tive correlation with the Ocean Nino Index(r=0.74,P<0.01,n=38),indicating that El Niño-Southern Oscillation(ENSO)has a significant impact on the interannual variability of precipitationδ^(18)O in southern China.Further anal⁃ysis shows that ENSO affects the precipitationδ^(18)O by controlling the convective activities over the Bay of Bengal and the South China Sea and the intensity of the west Pacific subtropical high,but the effect of the convective ac⁃tivities over the primary moisture regions may be stronger.In addition,the correlation between precipitationδ^(18)O and ENSO is not stable during different periods,which will lead to large uncertainties in ENSO reconstruction based on stalagmitesδ^(18)O records in Asian Monsoon regions.