Potential vorticity control of the Brewer-Dobson circulation

布鲁尔-多布森环流的位涡控制

• 批准号: NE/H005803/1
• 负责人: Richard Scott
• 金额: $ 26.38万
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH005803%2F1
• 关键词: Potential; vorticity; control; Brewer; Dobson

The Brewer-Dobson circulation, the slow, persistent ascent of tropical tropospheric air into the stratosphere and its poleward and downward recirculation, plays a key role in determining the chemical composition of the entire middle atmosphere with profound effects on the earth system. It is responsible for the long-time and long-range transport of chemical species within the stratosphere, notably those involved in ozone chemistry. Its ascending branch causes local cooling near the tropical tropopause, controlling the dehydration of air ascending into the stratosphere and hence the distribution of stratospheric water vapour and the formation of polar stratospheric clouds. It therefore plays a central role in our estimates for ozone recovery over the next 50 years. Further, through its influence on the distribution of stratospheric water vapour, carbon dioxide, and ozone it influences stratospheric radiative heating, which in turn affects stratospheric dynamics and ultimately, through dynamical coupling with the troposphere, surface climate. There is mounting evidence from numerical climate models that tropical upwelling from the Brewer-Dobson circulation is increasing in strength, and will continue to do so in a warming climate. Broadly speaking, the proposed work will attempt to better understand the processes responsible for this trend and to establish how robust the trend is to uncertainties in current climate models. It will do this mostly by examining a dynamical quantity called the potential vorticity, a measure of the rotation of air parcels that takes into account local density stratification and the background rotation of the Earth. The variation of potential vorticity with latitude, mostly due to the differential rotation of the planet, allows a type of wave motion, Rossby waves, to propagate up into the atmosphere. These waves can break, much like water waves break on a beach, and where they do so they cause a local deposition of momentum, which forces air parcels to move poleward in order to conserve their angular momentum. It is this basic process that drives the Brewer-Dobson circulation. However, much remains uncertain about the distribution of these waves in the atmosphere and where they eventually break. Much depends on the details of the background potential vorticity distribution, which, however, tends to organise itself into a highly inhomogeneous distribution with regions of very steep gradients separated by regions of very weak gradients. These inhomogeneities are notoriously difficult to represent in numerical models because of limited horizontal resolution. The proposed work will therefore consider in some detail the nature of wave propagation and breaking on this inhomogeneous potential vorticity distribution, how such propagation and breaking is affected when the inhomogeneities are poorly represented, and how this in turn affects the Brewer-Dobson circulation.

布鲁尔-多布森环流，即热带对流层空气缓慢、持续地上升到平流层及其向极地和向下的再循环，在确定整个中层大气的化学成分方面发挥着关键作用，对地球系统产生深远的影响。它负责化学物质在平流层内的长期和远距离运输，特别是那些涉及臭氧化学的化学物质。它的上升分支导致热带对流层顶附近局部变冷，控制上升到平流层的空气脱水，从而控制平流层水蒸气的分布和极地平流层云的形成。因此，它在我们对未来 50 年臭氧恢复的估计中发挥着核心作用。此外，通过影响平流层水蒸气、二氧化碳和臭氧的分布，它影响平流层辐射加热，进而影响平流层动力学，并最终通过与对流层的动力学耦合影响地表气候。数值气候模型越来越多的证据表明，布鲁尔-多布森环流的热带上升流正在增强，并且在气候变暖的情况下将继续增强。从广义上讲，拟议的工作将试图更好地理解造成这一趋势的过程，并确定这一趋势对当前气候模型的不确定性的影响有多大。它将主要通过检查称为位涡度的动态量来实现这一点，位涡度是一种考虑局部密度分层和地球背景旋转的空气团旋转的度量。位涡度随纬度的变化（主要是由于行星的差异自转）使得一种波动（罗斯贝波）能够传播到大气中。这些波浪会破裂，就像水波在海滩上破裂一样，它们会导致动量的局部沉积，迫使空气团向极地移动，以保存其角动量。正是这个基本过程驱动了布鲁尔-多布森循环。然而，这些波在大气中的分布以及它们最终在哪里破裂仍然存在很多不确定性。很大程度上取决于背景位涡分布的细节，然而，背景位涡分布往往会组织成高度不均匀的分布，其中梯度非常陡的区域被梯度非常弱的区域分开。由于水平分辨率有限，这些不均匀性很难在数值模型中表示。因此，拟议的工作将详细考虑这种不均匀位涡分布上的波传播和破碎的性质，当不均匀性表现不佳时如何影响这种传播和破碎，以及这反过来又如何影响布鲁尔-多布森环流。

项目成果

The onset of the barotropic sudden warming in a global model

全球模型中正压突然变暖的开始

• DOI: 10.1002/qj.2580
• 发表时间: 2015
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Liu Y

The role of planetary waves in the tropospheric jet response to stratospheric cooling

行星波在对流层急流对平流层冷却的响应中的作用

• DOI: 10.1002/2016gl067849
• 发表时间: 2016
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Smith K

A new class of vacillations of the stratospheric polar vortex

平流层极地涡旋的一类新的波动

• DOI: 10.1002/qj.2788
• 发表时间: 2016
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Scott R

On the formation and maintenance of the stratospheric surf zone as inferred from the zonally averaged potential vorticity distribution

从纬向平均位涡分布推断平流层冲浪区的形成与维持

• DOI: 10.1002/qj.2377
• 发表时间: 2014
• 期刊: Quarterly Journal of the Royal Meteorological Society
• 影响因子: 8.9
• 作者: Scott R