古气候模拟中古地理边界条件重建的不确定性研究^*

Uncertainty in reconstructing palaeogeographic boundary conditions in palaeoclimate modelling

摘要

随着气候模式在古气候研究中的应用越发广泛,更加准确的古地理边界条件重建成为研究深时气候变化机制的关键,而古地理边界条件重建过程中的不确定性却少有人关注。本研究基于古海陆分布、古海深、古地形重建方法及资料选择,研究古地理边界条件重建过程中的不确定性以及其对气候模式模拟结果的影响。结果显示,重建过程中板块运动模型的选择、海陆分布的修正、海洋洋壳年龄数据的更新、大洋深度—洋壳年龄关系模型选择、沉积物模型选择以及古地形高度代用指标的选择都会导致不同的古地理边界条件重建结果。更重要的是,这种古地理边界条件的差异会进一步影响模式模拟结果中的温度、盐度以及洋流等重要的气候环境变量。这表明重建气候模式中古地理边界条件时需根据具体需求合理选择重建资料,同时也需基于密集和可靠的代用指标进一步优化重建资料,从而减少古地理边界条件对古气候模式结果可靠性的影响。

Abstract

As climate models are increasingly applied in palaeoclimate studies,the reconstruction of more accurate palaeogeographic boundary conditions has become a key factor in understanding deep-time climate change mechanisms. However,the uncertainty in this reconstruction process has received little attention. This study investigates this uncertainty and its impact on model simulation results,based on reconstruction methods and data selection for palaeo-sea-land distribution,palaeo-sea depth,and palaeo-topography. Our results show that: (1)When reconstructing sea-land distribution,choice of reference plate movement models significantly affects the latitude and longitude of the reconstructed plates,so this demonstrate that model selection should align with research goals. Moreover,accurate correction of sea-land distribution requires multiple palaeoenvironmental proxy indicators,considering their uncertainties. (2)The reconstruction of palaeo-sea depth is more uncertain due to its complex process. Updating the oceanic crust age,choosing a depth-crust age relationship model,selecting a sediment model,and adjusting depth in key areas can all lead to different ocean depth reconstruction results. In particular,special attention should be paid to critical areas like sea channels,the state of this areas directly affect ocean current patterns and temperature-salinity changes in some ocean basins. (3)The uncertainty of palaeo-topography reconstruction is mainly influenced by factors such as the richness and uncertainty of height proxy indicators. (4)Correcting sea-land distribution and reconstructing sea depth leads to differences in basin size and seabed topography. These differences directly impact ocean currents and air-sea exchanges. In summary,uncertainty arises at every step of the palaeogeographic boundary conditions reconstruction process,which will greatly affect the accuracy of model output. To mitigate this,optimizing reconstructions by adding more proxy indicators will be required. Additionally,using multi-model results and geological records for verification is critical when analyzing climate model output,involving palaeogeographic boundary uncertainty.

关键词

古气候 / 气候模式 / 古地理重建 / 古气候边界条件 / 古气候模拟

Key words

palaeoclimate / climate model / palaeogeographic reconstruction / palaeoclimate boundary conditions / palaeoclimate modelling

基金资助

*厦门市科技局自然科学基金项目(批准号: 3502Z20227021)和中央高校基本科研业务费专项项目(批准号: 20720210079)共同资助