Modeling oxygen isotopes in the Pliocene: Large‐scale features over the land and ocean
Modeling oxygen isotopes in the Pliocene: Large‐scale features over the land and ocean
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DOI：
10.1002/2014pa002774
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发表时间：
2015-04
期刊：
影响因子：
--
通讯作者：
J. Tindall;A. Haywood
中科院分区：
文献类型：
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作者：
J. Tindall;A. Haywood
本文利用第一个同位素大气环流模式（GCM）模拟上新世，讨论了δ 18 O测量结果对温暖气候的解释。该模型表明，上新世海洋表面δ 18 O（δ 18 Osw）的空间分布与前工业化时期相似，但北极和沿海地区相对亏损，而南大西洋和地中海地区相对富集。模拟的δ 18 Osw异常与模拟的盐度异常密切相关，支持用δ 18 Osw作为古盐度代用指标。模拟上新世降水δ 18 O（δ 18 Op）相对于工业化前值有所富集（但在某些热带地区亏损<2‰）。虽然通常浓度较低（<4‰），但在冰盖地区浓度可达25‰。在热带地区，δ 18 Op异常与降水量异常有关，尽管两者之间通常存在空间偏移。这种偏移表明，在解释δ 18 Op时，降水变化的位置比幅度更不确定。在高纬度地区，δ 18 Op异常与温度异常有关;然而，这种关系既不是线性的，也不是空间上一致的：大的δ 18 Op信号并不总是转化为大的温度信号。这些结果表明，同位素模拟可以增强气候模式和气候代用数据之间的协同作用。该模型可以将代理数据与气候以基于物理的方式联系起来，即使这种关系是复杂的和非本地的。δ 18 O与气候的关系，在这里从一个GCM确定，不能确定从转换函数或简单的模型。
The first isotope-enabled general circulation model (GCM) simulations of the Pliocene are used to discuss the interpretation of δ18O measurements for a warm climate. The model suggests that spatial patterns of Pliocene ocean surface δ18O ( δ18Osw) were similar to those of the preindustrial period; however, Arctic and coastal regions were relatively depleted, while South Atlantic and Mediterranean regions were relatively enriched. Modeled δ18Osw anomalies are closely related to modeled salinity anomalies, which supports using δ18Osw as a paleosalinity proxy. Modeled Pliocene precipitation δ18O ( δ18Op) was enriched relative to the preindustrial values (but with depletion of <2‰ over some tropical regions). While usually modest (<4‰), the enrichment can reach 25‰ over ice sheet regions. In the tropics δ18Op anomalies are related to precipitation amount anomalies, although there is usually a spatial offset between the two. This offset suggests that the location of precipitation change is more uncertain than the amplitude when interpreting δ18Op. At high latitudes δ18Op anomalies relate to temperature anomalies; however, the relationship is neither linear nor spatially coincident: a large δ18Op signal does not always translate to a large temperature signal. These results suggest that isotope modeling can lead to enhanced synergy between climate models and climate proxy data. The model can relate proxy data to climate in a physically based way even when the relationship is complex and nonlocal. The δ18O-climate relationships, identified here from a GCM, could not be determined from transfer functions or simple models.