Modeling of small scale processes in Antarctic sea ice and their impact on the biological pump in the future Southern Ocean - a physical-biological coupled bi-scale approach

南极海冰小尺度过程的建模及其对未来南大洋生物泵的影响——物理-生物耦合双尺度方法

• 批准号: 463296570
• 负责人: Professor Dr.-Ing. Tim Ricken
• 金额: --
• 依托单位: Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/463296570?language=en
• 关键词: Modeling; small; scale; processes; Antarctic

The seasonal variability of the global sea ice cover is an important component of the global climate. However, the small-scale influence of sea ice is still insufficiently described in global climate models. Therefore, this proposal aims to mathematically describe the key physical (P) and bio-geo-chemical (BGC) processes in sea ice using a high-fidelity two-scale model. The results can then be parameterized and incorporated into global climate models (GCMs), thus improving the predictive power.Ocean warming will significantly change the microstructure of sea ice. Thus, we develop a P-BGC model of an Antarctic sea ice floe to mathematically describe the complex coupled relationships between ice formation, nutrient transport, salinity and brine channel distribution, photosynthesis and carbonate chemistry. We use this model to simulate different scenarios of sea ice formation and its effects on the growth of sea ice algae, which have a significant impact on vertical carbon export (biological carbon pump).Thus, this project contributes significantly to the research topic '3.2.D - Improved understanding of polar processes and mechanisms'. In detail, we address three overarching goals:Step 1: Description of the sea ice structure We use a coupled bi-scale model to describe relevant aspects of freezing and melting in connection with deformation, salinity and brine transport. On the macroscopic level, a continuum mechanical description within the framework of the extended theory of porous media (eTPM) is performed. This allows the description of deformation, transport and reaction processes via a coupled set of partial differential equations (PDE). For the physical phenomenon of phase transformation between water and ice, the phase field model (PF) provides a micro-scale, which also consists of coupled PDEs. This results in a PDE-PDE coupling.Step 2: Coupling with the extended RecoM2 module as micro-scale model This allows the description of the BGC phenomena. The RecoM2 module consists of a system of equations of ordinary differential equations, so that a PDE-ODE coupling to a P-BGC model is performed. Step 3: Evaluation of the model approaches This includes the verification and validation of the combined P-BGC model using literature and experimental data. For the use of the high-resolution two-scale P-BGC model in global climate models the calculation efficiency has to be increased. For this purpose, reduced-order model (ROM) to generate surrogates of the full order model (FOM) are applied, which decrease the model complexity, e.g. by data-driven machine learning (ML) techniques or generalized proper decomposition (GPD).

全球海冰覆盖的季节性变化是全球气候的重要组成部分。然而，海冰的小尺度影响在全球气候模式中仍然没有得到充分的描述。因此，本建议的目的是数学描述的关键物理（P）和生物地球化学（BGC）的海冰使用高保真度的双尺度模式的过程。这些结果可以被参数化并纳入全球气候模型（GCM），从而提高预测能力。海洋变暖将显著改变海冰的微观结构。因此，我们开发了一个P-BGC模型的南极海冰浮冰数学描述冰的形成，营养盐输送，盐度和盐水通道分布，光合作用和碳酸盐化学之间的复杂耦合关系。我们利用该模式模拟了海冰形成的不同情景及其对海冰藻类生长的影响，这对垂直碳输出（生物碳泵）有重要影响。因此，该项目对研究主题“3.2.D -提高对极地过程和机制的理解”做出了重大贡献。详细地说，我们解决三个首要目标：第1步：描述海冰结构我们使用耦合双尺度模型来描述与变形，盐度和盐水输送有关的冻结和融化的相关方面。在宏观层面上，连续介质力学描述的扩展理论的多孔介质（eTPM）的框架内进行。这允许通过一组耦合的偏微分方程（PDE）的变形，运输和反应过程的描述。对于冰与水之间的相变这一物理现象，相场模型（PF）提供了一个微观尺度，也是由耦合偏微分方程组成。第二步：与扩展的PDEM 2模块耦合作为微尺度模型这允许描述BGC现象。该PDEM 2模块由一个常微分方程的方程组组成，以便执行PDE-ODE耦合到P-BGC模型。第三步：这包括使用文献和实验数据对组合P-BGC模型进行验证和确认。在全球气候模式中使用高分辨率双尺度P-BGC模式，需要提高计算效率。为此，应用降阶模型（ROM）来生成全阶模型（FOM）的代理，这降低了模型复杂性，例如通过数据驱动的机器学习（ML）技术或广义适当分解（GPD）。