全球变暖背景下海表淡水通量对AMOC的影响及机理研究

大西洋经向翻转流（AMOC）强度的改变往往引起全球性的气候变化，未来AMOC如何演变是学者普遍关心的问题。海表淡水通量是决定海水密度的关键因素，其变化对AMOC未来演变有重大影响。在耦合气候系统里，海表淡水通量与其他物理量相互作用，使我们较难评估海表淡水通量对AMOC的单独影响。前人多通过简单理想化的淡水强迫试验研究AMOC的响应，但在全球变暖背景下北大西洋海表淡水通量呈现出复杂的空间变化格局，这种变化会如何影响AMOC未来的演变目前尚不清楚。本项目拟采用高分辨率的耦合气候模式，利用部分耦合的试验方法分离出北大西洋海表淡水通量的单独作用，并结合动力诊断分析方法，首先分析全球变暖背景下北大西洋海表淡水通量的时空变化特征，然后定量研究其对AMOC演变的具体影响，最后揭示其影响不同阶段AMOC演变的动力机制。本项目研究将有助于深刻认识全球变暖背景下AMOC的演变规律。

Changes in the intensity of the Atlantic meridional overturning circulation (AMOC) often induce global climate changes. How the AMOC will evolve in the future is a matter of our general concern. The sea surface freshwater flux is one of the key factors that determine the density of seawater, and its change in the future will have a significant impact on the AMOC evolution. However, in a coupled climate system, the sea surface freshwater flux interacts with other physical quantities, which makes us difficult to evaluate the separate effect of sea surface freshwater flux on AMOC. Most of current studies focus on the response of AMOC to idealized freshwater flux forcing. However, in a warming climate, the North Atlantic sea surface freshwater flux change exhibits a complex spatial pattern. How it will affect the AMOC in the future is still unknown. This project plans to isolate the individual effect of North Atlantic surface freshwater flux using the partial coupling method in a high-resolution climate model. Combined with diagnostic analysis methods, we aim to analyze the temporal and spatial characteristics of North Atlantic sea surface freshwater flux change under global warming, quantify its contribution to the AMOC evolution, and reveal the dynamic process that how the North Atlantic surface freshwater flux affects the AMOC evolution at different stage. This project will help to understand the AMOC evolution in the future.