Inter-annual tropical Pacific climate variability in an isotope-enabled CGCM: implications for interpreting coral stable oxygen isotope records of ENSO
Inter-annual tropical Pacific climate variability in an isotope-enabled CGCM: implications for interpreting coral stable oxygen isotope records of ENSO
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DOI：
10.5194/cp-9-1543-2013
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发表时间：
2013-07
影响因子：
4.3
通讯作者：
T. Russon;A. Tudhope;G. Hegerl;M. Collins;J. Tindall
中科院分区：
文献类型：
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作者：
T. Russon;A. Tudhope;G. Hegerl;M. Collins;J. Tindall
水同位素耦合大气-海洋气候模式允许探索由海表温度（SST）和海水同位素组成（18 Osw）引起的珊瑚稳定氧同位素（18 Ocoral）变率的相对贡献。同位素驱动的HadCM3耦合环流模式的非强迫行为表明，osh年际变化对模式18 Ocoral的贡献程度具有强烈的空间依赖性，从赤道东太平洋的可忽略不计到西太平洋部分地区占ooral变化的50%不等。在后一种情况下，海温年际变化的一个重要组成部分与海温的年际变化相关，这意味着有效的当地18珊瑚-海温关系的当地校准可能是必不可少的。此外，18w和海温之间的关系可能是非线性的，因此，在仅依赖海温的线性背景下，赤道太平洋中部和西部的模式解释导致与大厄尔尼诺事件相关的海温异常高估（高达20%）。基于盐度的伪珊瑚方法的模型内评估表明，这种方法捕获了模型18 Osw行为的一阶特征。然而，伪珊瑚的效用受到时间盐度- 18w关系的模拟斜率中所见的空间变异性程度的限制。
Water isotope-enabled coupled atmosphere-ocean climate models allow for exploration of the relative contri- butions to coral stable oxygen isotope ( 18 Ocoral) variability arising from sea surface temperature (SST) and the isotopic composition of seawater ( 18 Osw). The unforced behaviour of the isotope-enabled HadCM3 coupled general circulation model suggests that the extent to which inter-annual 18 Osw variability contributes to that in model 18 Ocoral is strongly spatially dependent, ranging from being negligible in the eastern equatorial Pacific to accounting for 50 % of 18 Ocoral variance in parts of the western Pacific. In these latter cases, a significant component of the inter-annual 18 Osw variabil- ity is correlated to that in SST, meaning that local calibra- tions of the effective local 18 Ocoral-SST relationships are likely to be essential. Furthermore, the relationship between 18 Osw and SST can be non-linear, such that the model inter- pretation of central and western equatorial Pacific 18 Ocoral in the context of a linear dependence on SST alone leads to overestimation (by up to 20 %) of the SST anomalies asso- ciated with large El Nievents. Intra-model evaluation of a salinity-based pseudo-coral approach shows that such an ap- proach captures the first-order features of the model 18 Osw behaviour. However, the utility of the pseudo-corals is lim- ited by the extent of spatial variability seen within the mod- elled slopes of the temporal salinity- 18 Osw relationship.