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; 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异性是全球气候的重要组成部分。但是，在全球气候模型中，海冰的小规模影响仍然不足。因此，该提案旨在使用高保真性的两尺度模型来数学上描述海冰中的关键物理（P）和生物斑点化学（BGC）过程。然后可以将结果进行参数化并将其纳入全球气候模型（GCM），从而提高预测能力。海洋变暖将显着改变海冰的微观结构。因此，我们开发了一种南极海冰浮子的P-BGC模型，以数学描述冰形成，营养运输，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。我们使用该模型来模拟海冰形成的不同情况及其对海冰藻类生长的影响，这对垂直碳出口（生物碳泵）产生了重大影响。因此，该项目对研究主题'3.2.D-改善了对极性过程和机制的理解有了重大贡献。详细说明，我们解决了三个总体目标：步骤1：海冰结构的描述，我们使用耦合的双尺度模型来描述与变形，盐度和盐度运输有关的冻结和融化的相关方面。在宏观水平上，进行了多孔介质（ETPM）框架内的连续机械描述。这允许描述通过一组偏微分方程（PDE）耦合的变形，传输和反应过程。对于水和冰之间相变的物理现象，相位场模型（PF）提供了一个微尺度，它也由耦合PDE组成。这会导致PDE-PDE耦合。步骤2：与扩展的ROCOM2模块作为微尺度模型耦合，这允许对BGC现象的描述。 ROCOM2模块由普通微分方程方程组成，因此执行了与P-BGC模型的PDE-ODE耦合。步骤3：对模型方法的评估包括使用文献和实验数据对合并的P-BGC模型进行验证和验证。为了在全球气候模型中使用高分辨率的两尺度P-BGC模型，必须提高计算效率。为此，应用了减少阶模型（ROM）生成完整阶模型（FOM）的替代物，从而降低了模型的复杂性，例如通过数据驱动的机器学习（ML）技术或通用的适当分解（GPD）。