Aerosol-Cloud Coupling And Climate Interactions in the Arctic

北极的气溶胶-云耦合和气候相互作用

• 批准号: NE/I028297/1
• 负责人: Ian Renfrew
• 金额: $ 34.03万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI028297%2F1
• 关键词: Aerosol; Cloud; Coupling; Climate; Interactions

The climate of the Arctic is changing faster than that almost anywhere else on Earth, warming at a rate of twice the global average. This warming is accompanied by a rapid melting of the sea ice - 2007 saw a record minimum in summer ice extent, and the years since have seen the 2nd and 3rd lowest summer ice extents on record - and a thinning of the ice that remains from year to year. The strong warming in the Arctic is due to several positive feedback processes, including a sea-ice albedo feedback (warmer conditions melt ice, lowering the average reflectivity of the mixed ice/ocean surface and thus absorbing more solar radiation, leading to increased ice melt and further lowering of the albedo) and several cloud feedbacks. Over most of the globe low clouds act to cool the surface since they reflect sunlight; over the arctic the highly reflective ice surface reduces the significance of cloud reflectivity, and the absorption of infrared radiation by cloud water droplets becomes the dominant effect - this acts to trap heat below cloud, warming the surface.Although climate models generally show a strong greenhouse warming effect in the Arctic, they also disagree with each other more in the Arctic than anywhere else, producing a wider range of possible future climate conditions. The models also tend not to be able to reproduce current Arctic climate conditions very accurately. This large uncertainty in models of the Arctic climate results primarily from poor representation of physical processes within the models, and some unique and particularly challenging conditions. The largest single source of uncertainty is the representation of clouds. The models use simple representations of cloud properties that were developed from observations in mid latitude or tropical cloud systems - very different conditions from those that exist in the Arctic. This project will make airborne in situ measurements of cloud microphysical properties, the vertical structure of the boundary layer and aerosol properties, and the fluxes of solar and infra red radiation above, below, and within cloud. It will also measure the production rates and properties of aerosol at the surface and their variability with season and extent of sea ice cover. These measurements will be used, along with a range of numerical models of aerosol and cloud processes, and atmospheric dynamics to evaluate the interactions between sea ice extent, aerosol production and cloud properties. New and improved descriptions of these processes suitable for use within climate models will be developed, tested, and implemented within the MetOffice climate model HadGEM. The ability of the current MetOffice models to reproduce the observed Arctic cloud and boundary layer properties will be tested, and the impact of the new parameterization schemes evaluated.Finally we will undertake a series of climate simulations to examine how future climate will evolve, and the feedbacks between warming of the Arctic, melting of sea ice, production of aerosol, and the properties of clouds evaluated.

北极的气候变化速度比地球上几乎任何其他地方都快，变暖速度是全球平均水平的两倍。这种变暖伴随着海冰的快速融化——2007年夏季冰面积创下了历史最低纪录，此后的几年里，夏季冰面积出现了有记录以来第二和第三低的水平——并且自去年以来剩余的冰变薄。到年。北极的强烈变暖是由于几个正反馈过程造成的，包括海冰反照率反馈（温暖的条件使冰融化，降低了混合冰/海洋表面的平均反射率，从而吸收更多的太阳辐射，导致冰融化增加）以及进一步降低反照率）和一些云反馈。在全球大部分地区，低云会反射阳光，从而起到冷却地表的作用。在北极上空，高反射冰面降低了云反射率的重要性，云水滴对红外辐射的吸收成为主导效应——这将热量捕获在云层下方，使地表变暖。尽管气候模型通常显示出强烈的温室效应除了北极变暖效应之外，它们在北极的分歧也比其他地方更大，从而产生了更广泛的未来可能的气候条件。这些模型也往往无法非常准确地再现当前的北极气候条件。北极气候模型的巨大不确定性主要是由于模型中物理过程的代表性较差以及一些独特且特别具有挑战性的条件造成的。不确定性的最大单一来源是云的表示。这些模型使用云特性的简单表示，这些特性是根据中纬度或热带云系统的观测得出的——与北极存在的条件非常不同。该项目将对云的微物理特性、边界层的垂直结构和气溶胶特性以及云上方、下方和内部的太阳和红外辐射通量进行机载原位测量。它还将测量表面气溶胶的产生率和特性及其随季节和海冰覆盖范围的变化。这些测量结果将与一系列气溶胶和云过程的数值模型以及大气动力学一起用于评估海冰范围、气溶胶产生和云特性之间的相互作用。适用于气候模型的这些过程的新的和改进的描述将在气象局气候模型 HadGEM 中开发、测试和实施。当前气象局模型重现观测到的北极云和边界层特性的能力将受到测试，并评估新参数化方案的影响。最后，我们将进行一系列气候模拟，以研究未来气候将如何演变，以及北极变暖、海冰融化、气溶胶的产生以及评估的云特性之间的反馈。

项目成果

Decreasing intensity of open-ocean convection in the Greenland and Iceland seas

格陵兰岛和冰岛海的公海对流强度减弱

• DOI: 10.1038/nclimate2688
• 发表时间: 2015-06-29
• 期刊: Nature Climate Change
• 影响因子: 30.7
• 作者: G. Moore;K. Våge;R. Pickart;I. Renfrew
• 通讯作者: I. Renfrew

Structure of a shear-line polar low

切变线极地低压的结构

• DOI: http://dx.10.1002/qj.2911
• 发表时间: 2016
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Sergeev D

Improved Simulation of the Polar Atmospheric Boundary Layer by Accounting for Aerodynamic Roughness in the Parameterization of Surface Scalar Exchange Over Sea Ice

通过考虑海冰表面标量交换参数化中的气动粗糙度来改进极地大气边界层的模拟

• DOI: http://dx.10.1029/2022ms003305
• 发表时间: 2023
• 期刊: Journal of Advances in Modeling Earth Systems
• 影响因子: 6.8
• 作者: Elvidge A

Improved simulation of the polar atmospheric boundary layer by accounting for aerodynamic roughness in the parameterisation of surface scalar exchange over sea ice

通过考虑海冰表面标量交换参数化中的空气动力学粗糙度，改进极地大气边界层的模拟

• DOI: http://dx.10.1002/essoar.10512220.1
• 发表时间: 2022
• 作者: Elvidge A

Atmospheric sensitivity to marginal-ice-zone drag: Local and global responses

大气对边缘冰区阻力的敏感性：局部和全球响应

• DOI: http://dx.10.1002/qj.3486
• 发表时间: 2019
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Renfrew I