Improved projections of winds at the crossroads between Antarctica and the Southern Ocean

改进了南极洲和南大洋交界处的风预测

• 批准号: NE/V000691/1
• 负责人: Thomas Bracegirdle
• 金额: $ 69.93万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV000691%2F1
• 关键词: Improved; projections; winds; crossroads; between

The coastal region of Antarctica links the Southern Ocean to the Antarctic continent and is where many of the key interactions that govern Antarctica's impact on the global climate system take place. Scientists have studied winds at mid-latitudes over the Southern Ocean and over the Antarctic continent, but much less attention has been paid to the marine winds just offshore from Antarctica. Numerical models of the ocean and atmosphere are now run on small enough grids that these coastal winds can be resolved and represented reliably. However, this needs to be tested in the current generation of climate models. It is important that climate models have a good representation of these coastal winds for the following reasons: - Coastal winds influence the flow rate of major Antarctic glaciers and their associated impacts on global sea level. - Winds over coastal polynyas (areas of unfrozen sea within the ice pack) drive cooling and sinking of the densest water in the world ocean, known as Antarctic Bottom Water (AABW), which contributes to storing the extra heat and carbon released into the atmosphere by humans. - Realistic surface wind fields in climate models are needed to produce realistic distributions of sea ice. This is important in controlling the amount heat and moisture convergence into the Antarctic continent by capping off evaporation and heat loss from the ocean surface. Additionally, since sea ice formation enriches surface waters with salt, it is integral to the formation and sinking of dense AABW. Reliable projections of future change in AMCWs, and related regional and global impacts, will require their realistic representation in climate models. We will make use of a new collection of state-of-the-art climate model output, the Coupled Model Inter-comparison Project Phase 6 (CMIP6). In collaboration with the Met Office, sensitivity studies using their IPCC-class Unified Model (MetUM) will enable us to understand how sensitive AMCWs are to changes in model configuration. This will tell us which physical processes climate models need to get right to accurately represent the structure and variability of AMCWs. We will improve the evaluation of observed winds from Antarctic stations, research and supply vessels, drifting buoys, and marine winds from satellites to assess the quality of a range of different gridded wind data products, which are based on both observations and observationally-constrained numerical modelling. The best performing products will be used to evaluate climate model performance. An established framework for model evaluation is the concept of climate model 'metrics', which can quantify a key process or feature of the climate system, usually with a single value, that can be calculated from both model output and observational reference data (in our case observationally-based wind products). We will develop and use metrics to evaluate the performance of CMIP6 models in representing AMCWs, including configurations participating in its high-resolution sub-project HighResMIP. This, along with improved process understanding, will help to reduce uncertainty in projections of future change.The research outcomes will be: - Improved 21st century projections of AMCWs from the latest state-of-the-art climate and earth system models.- Observational metrics of AMCWs that can be applied to gridded climate model output. - A dataset of historical in-situ meteorological observations of marine coastal Antarctica building on the NERC ORCHESTRA project.- Identify the best of the current generation of wind products for the Antarctic coastal region. - Evaluation of the representation of AMCWs in the MetUM which, in combination with planned sensitivity studies, should ultimately facilitate accelerated model development.- Career development for two early career researchers giving experience in climate modelling, analysing large datasets, networking and communication skills.

南极洲沿海地区将南大洋与南极大陆连接在一起，并且是制约南极洲对全球气候系统影响的许多关键相互作用发生的地方。科学家们研究了南大洋和南极大陆中纬度地区的风，但对南极洲近海的海风的关注要少得多。海洋和大气的数值模型现在在足够小的网格上运行，这些沿海风可以被解析和可靠地表示出来。然而，这需要在当前的气候模型中进行测试。重要的是，气候模式能够很好地反映这些沿海风，原因如下：-沿海风影响南极主要冰川的流速及其对全球海平面的相关影响。-沿海多冰湖（冰盖内未结冰的海域）上空的风促使世界海洋中密度最大的水——南极底水（AABW）——冷却和下沉，这有助于储存人类释放到大气中的额外热量和碳。-气候模式中需要真实的地面风场来产生真实的海冰分布。这对控制热量和水分向南极大陆的辐合很重要，因为它可以阻止海洋表面的蒸发和热量损失。此外，由于海冰的形成使地表水富含盐分，因此它是密集AABW形成和下沉的必要条件。对AMCWs未来变化以及相关的区域和全球影响的可靠预测，将需要它们在气候模式中具有现实的代表性。我们将利用最新气候模式产出的新集合，即耦合模式比对项目第6阶段（CMIP6）。在与英国气象局的合作下，使用ipcc级别的统一模型（MetUM）进行敏感性研究，将使我们能够了解AMCWs对模型配置变化的敏感性。这将告诉我们，气候模式需要正确处理哪些物理过程，才能准确地代表AMCWs的结构和变异性。我们将改进对南极站、研究和补给船、漂流浮标和卫星海风观测的评估，以评估一系列不同网格风数据产品的质量，这些数据产品既基于观测，也基于观测约束的数值模拟。表现最好的产品将用于评估气候模型的性能。模式评估的一个既定框架是气候模式“度量”的概念，它可以量化气候系统的一个关键过程或特征，通常只有一个值，可以从模式输出和观测参考数据（在我们的例子中是基于观测的风产品）中计算出来。我们将开发和使用度量来评估CMIP6模型在表示AMCWs方面的性能，包括参与其高分辨率子项目HighResMIP的配置。这与改进的过程理解一起，将有助于减少未来变化预测中的不确定性。研究成果将是：-根据最先进的最新气候和地球系统模式改进21世纪的AMCWs预估。-可应用于网格化气候模式输出的AMCWs观测指标。-在NERC ORCHESTRA项目上对南极海洋海岸建筑的历史现场气象观测数据集。-确定目前最适合南极沿海地区的风力产品。-评估生化武器在MetUM中的代表性，结合已计划的敏感性研究，最终应能促进加速模型的发展。-为两名早期职业研究人员提供职业发展，他们在气候建模、分析大型数据集、网络和沟通技巧方面具有经验。