Can energy fluxes be used to interpret glacial/interglacial precipitation changes in the tropics?
Can energy fluxes be used to interpret glacial/interglacial precipitation changes in the tropics?
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DOI：
10.1002/2017gl073103
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发表时间：
2017-06
影响因子：
5.2
通讯作者：
W. Roberts;P. Valdes;J. Singarayer
中科院分区：
文献类型：
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作者：
W. Roberts;P. Valdes;J. Singarayer
热输运与热带辐合带（ITCZ）位置关系的最新理论进展为解释过去热带降水型的变化提供了一个优雅的框架。利用一个非常大的气候模式模拟集合，我们研究了是否有可能使用这个框架来解释ITCZ的位置变化对冰期和间冰期边界条件的响应。研究发现，代表整个热带地区降水演变的热带降水质心与热输运变化的相关性最好。研究发现，ITCZ年平均对冰期和间冰期边界条件的响应与ITCZ年气候周期对季节日照周期的响应有很大不同。我们表明，造成这种情况的原因是，虽然哈德利环流在季节周期的热量输送中起主导作用，但在对强迫的年平均响应中，哈德利环流并不占主导地位。当我们从区域而不是纬向平均来看时，我们发现局地降水与纬向平均ITCZ或经向热输送的关系都很差。研究表明，当纬向平均ITCZ处于同一位置时，降水在空间上的变化也很大。这表明热输运在解释局部降水记录方面的作用有限；因此，利用热输运变化来解释单个古降水记录的范围有限。
Recent theoretical advances in the relationship between heat transport and the position of the Intertropical Convergence Zone (ITCZ) present an elegant framework through which to interpret past changes in tropical precipitation patterns. Using a very large ensemble of climate model simulations, we investigate whether it is possible to use this framework to interpret changes in the position of the ITCZ in response to glacial and interglacial boundary conditions. We find that the centroid of tropical precipitation, which represents the evolution of precipitation in the whole tropics, is best correlated with heat transport changes. We find that the response of the annual mean ITCZ to glacial and interglacial boundary conditions is quite different to the response of the climatological annual cycle of the ITCZ to the seasonal cycle of insolation. We show that the reason for this is that while the Hadley Circulation plays a dominant role in transporting heat over the seasonal cycle, in the annual mean response to forcing, the Hadley Circulation is not dominant. When we look regionally, rather than at the zonal mean, we find that local precipitation is poorly related either to the zonal mean ITCZ or to meridional heat transport. We demonstrate that precipitation is spatially highly variable even when the zonal mean ITCZ is in the same location. This suggests only limited use for heat transport in explaining local precipitation records; thus, there is limited scope for using heat transport changes to explain individual paleoprecipitation records.