研究人员报道了在印度尼西亚苏拉威西岛西南部，发现的洞穴沉积物氧同位素(δ18O)的记录，并将其与海洋大陆的洞穴沉积物氧同位素记录进行了比较。沿着 ITCZ 的一个横断面，利用洞穴沉积物 δ18O 的空间梯度变化，研究人员限制了过去 30,000 年里海洋大陆上 ITCZ 的变化。研究结果显示，随着气候边界条件的变化，从末次冰期到全新世，ITCZ 对流强度总体增强。在过去的30,000年里，区域 ITCZ 的平均位置在纬度上移动了不超过 3°，这与大气能量框架的推断相一致。
然而，与现代观测和未来变暖的模型模拟不同，ITCZ 在全新世晚期和末次冰期的大部分时间内都呈现变窄趋势，其扩张发生在海因里希冰期和全新世早中期。研究还发现，在末次冰期和冰消期，显著的千年尺度 ITCZ 变化与大西洋经向翻转环流(AMOC)的变化密切相关，而在全新世，ITCZ 变化主要受沃克环流长期变化的调节。
据悉，热带辐合带(ITCZ)通过对流强度、纬向位置和宽度的变化，对热带水文气候和全球水循环起着关键的调节作用。然而，ITCZ 的长期变率及其驱动机制尚不清楚，主要原因是在古气候代理记录中难以区分不同的 ITCZ 变量。
附：英文原文
Title: The strength, position, and width changes of the intertropical convergence zone since the Last Glacial Maximum
Author: Yuan, Shufang, Chiang, Hong-Wei, Liu, Guangxin, Bijaksana, Satria, He, Shaoneng, Jiang, Xiuyang, Imran, Andi M., Wicaksono, Satrio A., Wang, Xianfeng
Issue&Volume: 2023-11-6
Abstract: The intertropical convergence zone (ITCZ) plays a key role in regulating tropical hydroclimate and global water cycle through changes in its convection strength, latitudinal position, and width. The long-term variability of the ITCZ, along with the corresponding driving mechanisms, however, remains obscure, mainly because it is difficult to separate different ITCZ variables in paleoclimate proxy records. Here, we report a speleothem oxygen isotope (δ18O) record from southwestern Sulawesi, Indonesia, and compile it with other speleothem records from the Maritime Continent. Using the spatial gradient of speleothem δ18O along a transect across the ITCZ, we constrain ITCZ variabilities over the Maritime Continent during the past 30,000 y. We find that ITCZ convection strength overall intensified from the last glacial period to the Holocene, following changes in climate boundary conditions. The mean position of the regional ITCZ has moved latitudinally no more than 3° in the past 30,000 y, consistent with the deduction from the atmospheric energy framework. However, different from modern observations and model simulations for future warming, the ITCZ appeared narrower during both the late Holocene and most part of the last glacial period, and its expansion occurred during Heinrich stadials and the early-to-mid Holocene. We also find that during the last glacial and deglacial period, prominent millennial-scale ITCZ changes were closely tied to the variability of the Atlantic meridional overturning circulation (AMOC), whereas during the Holocene, they were predominantly modulated by the long-term variability of the Walker circulation.
DOI: 10.1073/pnas.2217064120
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2217064120