Centre for Southern Hemisphere Oceans Research (CSHOR), CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia.
CSIRO Climate Science Centre, Aspendale, Victoria, Australia.
Sci Rep. 2018 Sep 10;8(1):13500. doi: 10.1038/s41598-018-31842-3.
The Indian Ocean Dipole (IOD) is the dominant mode of interannual variability over the tropical Indian Ocean (IO) and its future changes are projected to impact the climate and weather of Australia, East Africa, and Indonesia. Understanding the response of the IOD to a warmer climate has been largely limited to studies of individual coupled general circulation models or multi-model ensembles. This has provided valuable insight into the IOD's projected response to increasing greenhouse gases but has limitations in accounting for the role of internal climate variability. Using the Community Earth System Model Large Ensemble (CESM-LE), the IOD is examined in thirty-five present-day and future simulations to determine how internal variability influences properties of the IOD and their response to a warmer climate. Despite small perturbations in the initial conditions as the only difference between ensemble members, significant relationships between the mean state of the IO and the IOD arise, leading to a spread in the projected IOD responses to increasing greenhouse gases. This is driven by the positive Bjerknes feedback, where small differences in mean thermocline depth, which are caused by internal climate variability, generate significant variations in IOD amplitude, skewness, and the climatological zonal sea surface temperature gradient.
印度洋偶极子（IOD）是热带印度洋（IO）上占主导地位的年际可变性模态，其未来变化预计将影响澳大利亚、东非和印度尼西亚的气候和天气。了解IOD 对更暖气候的响应在很大程度上仅限于对个别耦合的通用环流模型或多模型集合的研究。这为IOD 对不断增加的温室气体的预计响应提供了有价值的见解，但在解释内部气候变率的作用方面存在局限性。使用地球系统模式大集合（CESM-LE），在三十五项当前和未来的模拟中对 IOD 进行了检查，以确定内部变率如何影响 IOD 的特性及其对更暖气候的响应。尽管成员之间的唯一区别是初始条件的小干扰，但 IO 和 IOD 的平均状态之间会出现显著关系，从而导致对不断增加的温室气体的预测 IOD 响应出现差异。这是由正的贝吉龙反馈驱动的，其中由于内部气候变率引起的平均温跃层深度的微小差异会导致 IOD 幅度、偏度和气候纬向海表温度梯度的显著变化。
