Southern Hemisphere westerly wind changes during the Last Glacial Maximum: model-data comparison
Southern Hemisphere westerly wind changes during the Last Glacial Maximum: model-data comparison
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DOI：
10.1016/j.quascirev.2012.12.008
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发表时间：
2013-03
影响因子：
4
通讯作者：
L. Sime;K. Kohfeld;Corinne Le Quéré;E. Wolff;A. M. Boer;Robert M. Graham;L. Bopp
中科院分区：
文献类型：
--
作者：
L. Sime;K. Kohfeld;Corinne Le Quéré;E. Wolff;A. M. Boer;Robert M. Graham;L. Bopp
南半球（SH）西风被认为是全球海洋环流，生产力和碳储存的关键。例如，风向赤道方向的移动，虽然对南大洋环流有影响，但被认为是末次冰期大气中二氧化碳减少的主要原因。尽管风的重要性，目前还不清楚，从观测或模型结果，他们如何表现在末次冰期。在这里，进行大气模拟研究，以帮助确定可能的变化，在上海西风在末次冰期最大（LGM）。在末次盛冰期边界条件下，副高西风带最大值在850 hPa气压水平上增强了0.01 + 1 m s− 1，并向南移动了0.02 °。边界层稳定的影响，向赤道扩展LGM海冰可以导致一个小的明显的向赤道移动的风带在表面。进一步的敏感性分析与个别边界条件的变化表明，海面温度的变化是最强的因素背后的风的变化。HadAM3的大气模拟，沿着与公布的PMIP 2耦合气候模式模拟，然后评估对新合成的数据库的水分观测末次冰期。虽然水分数据是最常引用的证据，在LGM期间的SH风的大赤道向移动的支持，没有一个模型，产生现实的LGM降水变化显示这样一个大的赤道向移动。事实上，最能模拟湿度代用数据的模型是HadAM3 LGM模拟，它显示了一个小的向极风的转变。虽然我们不能在这里证明，一个大的赤道移动将无法重现的湿度数据，以及，我们表明，湿度代理不提供观测证据基础。
The Southern Hemisphere (SH) westerly winds are thought to be critical to global ocean circulation, productivity, and carbon storage. For example, an equatorward shift in the winds, though its affect on the Southern Ocean circulation, has been suggested as the leading cause for the reduction in atmospheric CO2during the Last Glacial period. Despite the importance of the winds, it is currently not clear, from observations or model results, how they behave during the Last Glacial. Here, an atmospheric modelling study is performed to help determine likely changes in the SH westerly winds during the Last Glacial Maximum (LGM). Using LGM boundary conditions, the maximum in SH westerlies is strengthened by ∼+1 m s−1and moved southward by ∼2° at the 850 hPa pressure level. Boundary layer stabilisation effects over equatorward extended LGM sea-ice can lead to a small apparent equatorward shift in the wind band at the surface. Further sensitivity analysis with individual boundary condition changes indicate that changes in sea surface temperatures are the strongest factor behind the wind change. The HadAM3 atmospheric simulations, along with published PMIP2 coupled climate model simulations, are then assessed against the newly synthesised database of moisture observations for the LGM. Although the moisture data is the most commonly cited evidence in support of a large equatorward shift in the SH winds during the LGM, none of the models that produce realistic LGM precipitation changes show such a large equatorward shift. In fact, the model which best simulates the moisture proxy data is the HadAM3 LGM simulation which shows a small poleward wind shift. While we cannot prove here that a large equatorward shift would not be able to reproduce the moisture data as well, we show that the moisture proxies do not provide an observational evidence base for it.