当前位置: X-MOL 学术Clim. Past › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Impact of Southern Ocean surface conditions on deep ocean circulation at the LGM: a model analysis
Climate of the Past ( IF 4.3 ) Pub Date : 2020-11-21 , DOI: 10.5194/cp-2020-148
Fanny Lhardy , Nathaëlle Bouttes , Didier M. Roche , Xavier Crosta , Claire Waelbroeck , Didier Paillard

Abstract. Changes in water mass distribution are considered to be a significant contributor to the atmospheric CO2 concentration drop to around 186 ppm recorded during the Last Glacial Maximum (LGM). Yet simulating a glacial Atlantic Meridional Overturning Circulation (AMOC) in agreement with paleotracer data remains a challenge, with most models from previous Paleoclimate Modelling Intercomparison Project (PMIP) phases showing a tendency to simulate a strong and deep North Atlantic Deep Water (NADW) instead of the shoaling inferred from proxy data. Conversely, the simulated Antarctic Bottom Water (AABW) is often reduced compared to its pre-industrial volume, and the Atlantic Ocean stratification is underestimated with respect to data. Inadequate representation of surface conditions, driving deep convection around Antarctica, may explain inaccurate simulated bottom water properties in the Southern Ocean. We investigate here the impact of a range of surface conditions in the Southern Ocean, using nine simulations obtained using different modelling choices and/or boundary conditions in the iLOVECLIM model. Based on data-model comparison of key parameters (sea-surface temperatures and sea ice), we find that only simulations with a cold Southern Ocean and a quite extensive sea-ice cover show an improved agreement with proxy data, despite systematic model biases in the seasonal and regional patterns. We then show that the only simulation which does not display a much deeper NADW is obtained by parameterizing the sinking of brines along Antarctica, a modelling choice reducing the open ocean convection in the Southern Ocean. These results highlight the importance of the representation of convection processes, which have a large impact on the water masses properties, while the choice of boundary conditions appears secondary for the model resolution and variables considered in this study.

中文翻译:

LGM南部海面条件对深海环流的影响:模型分析

摘要。水质分布的变化被认为是造成大气中CO 2的重要因素在上次冰河期(LGM)期间记录的浓度下降到186 ppm左右。然而,与古示踪剂数据相一致地模拟冰川大西洋经向翻转环流(AMOC)仍然是一个挑战,以前古气候模拟比对项目(PMIP)阶段的大多数模型都显示出模拟强而深的北大西洋深水(NADW)的趋势。从代理数据推断出的浅滩的百分比。相反,与工业化前的体积相比,模拟的南极底水(AABW)通常会减少,并且相对于数据而言,大西洋的分层被低估了。地表条件表示不充分,导致南极洲附近发生深对流,这可能解释了南大洋模拟的底水特性不准确的原因。我们在这里使用iLOVECLIM模型中使用不同的模型选择和/或边界条件获得的九次模拟,调查了南洋一系列地表条件的影响。根据关键参数(海表温度和海冰)的数据模型比较,我们发现,尽管存在系统模型偏差,但只有在南半球寒冷且海冰覆盖范围相当广的情况下,模拟显示出与代理数据的一致性提高。季节性和区域性模式。然后,我们表明,通过对沿南极洲下沉的盐水进行参数化,可以获得唯一不显示更深的NADW的模拟,这是减少南大洋对流对流的一种建模选择。这些结果凸显了对流过程的重要性,
更新日期:2020-11-22
down
wechat
bug