MOSAiC Boundary Layer

MOSAiC 边界层

• 批准号: NE/S002472/1
• 负责人: Ian Brooks
• 金额: $ 38.46万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS002472%2F1
• 关键词: MOSAiC; Boundary; Layer

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) initiative is a major international programme motivated by the rapid changes in Arctic climate observed over the last few decades. This is driven by an accelerated rise in the mean temperature of the Arctic; which is warming at 2-3 times the mean global rate. The most visible change is the dramatic reduction in sea ice extent, particularly of the summer minimum, which is decreasing at a rate of 13% per decade. These rapid changes are the result of a combination of feedback processes - the best known is the ice albedo feedback, whereby the loss of ice exposes the land or sea surface beneath, lowering the area mean albedo and allowing more solar radiation to be absorbed, which warms the surface and enhances ice melt. Other feedbacks relate to the vertical profiles of atmospheric temperature and humidity, cloud properties, and large-scale atmospheric circulation.While climate models also show enhanced warming in the Arctic, they do not reproduce many of the observed details of the change; for example they do not reproduce the very rapid decline in the summer sea ice minimum observed over the last 10 years, and there are big differences between models. This has a significant impact on our ability to predict the future state of climate system. Poor model performance results from multiple leading-order deficiencies in their representation of physical processes in the Arctic system. MOSAiC aims to address these through a large-scale coordinated approach, making simultaneous measurements of the many interdependent processes relevant to climate over a full calendar year. This approach is necessary because of the strong linkages and feedbacks between different parts of the Arctic climate system and the strong seasonality in many processes. The observational campaign will take place on, and around, the icebreaker Polarstern, which will be frozen in at the edge of the pack ice at the end of the summer melt. This provides ready access to both multi-year ice within the pack and to freshly forming ice just outside it. Measurements will be made of all components of the surface energy budget on both the upper and lower sides of the ice, along with ice thickness, temperature, physical properties, topography, and deformation over time. The processes controlling the energy budget, including synoptic-scale forcing, cloud properties, turbulent mixing, and the interactions between them, will be studied in detail. The measurements will be complemented by an extensive modelling programme, spanning a full range from small scale process studies up to global climate modelling.The last study to attempt anything remotely comparable to MOSAiC was the Surface Heat Budget of the Arctic (SHEBA) project, which undertook a much more limited set of measurements over 11 months in 1997-1998. The area where SHEBA took place is now ice-free every summer, emphasising the changes that have taken place since then.This proposal is a core contribution to the atmospheric science component of MOSAiC. We will make detailed measurements of lower atmosphere mean and turbulent dynamics for the duration of the measurement campaign. Several remote sensing systems (Doppler sodar and lidar) will be deployed to make continuous measurements mean wind profiles throughout the boundary layer. Retrievals of the vertical turbulence structure will allow the complex interactions between clouds, the boundary layer, and the surface to be understood and thus the primary controls on the surface energy budget and ice melt and formation to be better represented in models. Such detailed measurements of the vertical dynamic structure of the boundary layer will be unique in the Arctic, no comparable data set exists. In addition to our science they underpin many aspects of MOSAiC science being undertaken by other groups, and are considered essential by the MOSAiC atmospheric science coordinators.

北极气候研究多学科漂流观测站倡议是一个重大的国际方案，其动机是过去几十年来观测到的北极气候的迅速变化。这是由北极平均气温加速上升造成的;北极的变暖速度是全球平均速度的2-3倍。最明显的变化是海冰范围的急剧减少，特别是夏季最小值，以每十年13%的速度减少。这些快速变化是反馈过程组合的结果-最著名的是冰的负反馈，冰的损失使下面的陆地或海洋表面暴露，降低了面积平均负反馈，使更多的太阳辐射被吸收，这使表面变暖，加速了冰的融化。其他反馈与大气温度和湿度的垂直廓线、云的特性和大尺度大气环流有关，虽然气候模式也显示北极变暖加剧，但它们没有再现观测到的变化的许多细节;例如，它们没有再现过去10年观测到的夏季海冰最小值的快速下降，而且模式之间存在很大差异。这对我们预测气候系统未来状态的能力有重大影响。模型性能差的结果，从多个领先的顺序在北极系统的物理过程的代表性的缺陷。MOSAiC旨在通过大规模的协调方法来解决这些问题，在整个日历年内同时测量与气候相关的许多相互依赖的过程。这种方法是必要的，因为北极气候系统不同部分之间存在着密切的联系和反馈，而且许多过程具有很强的季节性。观测活动将在破冰船Polarstern上及其周围进行，该破冰船将在夏季融化结束时冻结在浮冰的边缘。这提供了随时访问内包多年的冰和新形成的冰外面。测量将由表面能量收支的所有组成部分的上部和下部的冰，沿着与冰的厚度，温度，物理性质，地形，和变形随着时间的推移。将详细研究控制能量收支的过程，包括天气尺度强迫、云的特性、湍流混合以及它们之间的相互作用。这些测量将得到一个广泛的模拟方案的补充，该方案涵盖从小尺度过程研究到全球气候模拟的全部范围，最近一次试图与MOSAiC进行远程比较的研究是北极表面热量收支项目，该项目在1997-1998年的11个月内进行了一系列有限得多的测量。SHEBA发生的地区现在每年夏天都没有冰，强调了自那时以来发生的变化。这一提议是对MOSAiC大气科学组成部分的核心贡献。我们将在测量活动期间对低层大气的平均和湍流动力学进行详细的测量。将部署几个遥感系统（多普勒声雷达和激光雷达），对整个边界层的平均风廓线进行连续测量。垂直湍流结构的检索将允许云，边界层和表面之间的复杂的相互作用被理解，从而在模型中更好地表示对表面能量收支和冰的融化和形成的主要控制。对边界层垂直动态结构进行如此详细的测量在北极是独一无二的，没有可比的数据集。除了我们的科学之外，它们还支持其他小组正在进行的MOSAiC科学的许多方面，并被MOSAiC大气科学协调员认为是必不可少的。

项目成果

Evaluation of Vertical Profiles and Atmospheric Boundary Layer Structure Using the Regional Climate Model CCLM during MOSAiC

MOSAiC 期间使用区域气候模式 CCLM 评估垂直剖面和大气边界层结构

• DOI: 10.3390/meteorology2020016
• 发表时间: 2023
• 期刊: Meteorology
• 作者: Heinemann G

Low-level jets over the Arctic Ocean during MOSAiC

MOSAiC 期间北冰洋上空的低空急流

• DOI: 10.1525/elementa.2022.00063
• 发表时间: 2022
• 期刊: Science of the Anthropocene
• 作者: López-García V