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Cloud System Resolving Modelling of the Tropical Atmosphere

热带大气云系统解析建模

基本信息

批准号：
NE/E00525X/1
负责人：
Steven Woolnough
金额：
$ 238.34万
依托单位：
University of Reading
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FE00525X%2F1
关键词：
Cloud System Resolving Modelling Tropical

项目摘要

The tropics are often described as the engine room of the Earth's climate system, powering the global circulations of the atmosphere and oceans. Absorption of sunlight heats the land and ocean surfaces strongly at low latitudes, producing convection that carries the energy from the surface into the atmosphere. Except over the deserts, the convection generates deep clouds that transport moisture evaporated from the ocean into the upper atmosphere. When these clouds rain, the release of 'latent heat' by condensing water produces further heating that drives the weather systems of the tropics and influences the winds all around the globe. But such deep convective clouds rarely exist in isolation; they are almost always organised into structures ranging from squall lines and cloud clusters to tropical storms, hurricanes and super-clusters; and convection varies on a wide range of timescales from that of an individual cloud element (hours), through the daily cycle to a plethora of waves with periods ranging up to the intra-seasonal oscillation, which can propagate around the world in 30-60 days. The tropical atmosphere thus organises itself on a huge range of space and timescales; the effect on the climate system is very different from that of random, or disorganised turbulence so that all these scales should be represented in a computer model if it is to reproduce the real world accurately. Until now, many of these effects have had to be represented in a highly simplified way, through a process known as parametrization. This tries to mimic the effect of the convection on the scales smaller than those represented explicitly in the model. The trouble is that across the cloud system from a few to a few hundreds of kilometres there is no preferred scale, and these scales span the range from those that are 'sub-grid' and therefore need parametrization to those which are resolved by the model. Even with the availability of modern supercomputers, this transition from parametrization to resolved motion takes place at around 100km in the latest climate models. All of the structures that occur in the real world below this scale are parametrized, so a completely artificial break occurs between what is resolved and what is parametrized. To compound the problem, the parametrization assumes that organization on scales which cannot be resolved is not important for determining the properties of the convection or its influence on the large-scale flow. But there is mounting evidence that this creates all sorts of problems in the models. Several decades have been invested in developing convection parametrizations and even after all this time and effort no fully satisfactory solution has been found. We therefore propose to take a radical but entirely logical approach to this problem. It is now possible to run models that do resolve convective systems explicitly (at least down to scales of around 1km) over very large domains that encompass all of the important scales mentioned above. Such cloud system resolving models provide a new tool for understanding how convection really works and organises itself, and how it should be parametrized in climate models. Our proposal links these models with new data from satellites and from the surface that will give us an unprecedented view of the evolution of clouds and rain-producing systems. We will bring this unique combination of modelling and observations to bear on what is regarded as one of the most fundamental problems in weather and climate. The results of the work will inform the development of a new generation of more accurate atmospheric models that will find employment in both climate prediction and weather forecasting.

热带地区通常被描述为地球气候系统的引擎室，为全球大气和海洋的循环提供动力。阳光的吸收使低纬度地区的陆地和海洋表面强烈升温，产生对流，将能量从地表带入大气。除了在沙漠上空，对流产生的深层云层将海洋蒸发的水分输送到上层大气中。当这些云层下雨时，冷凝水释放的“潜热”会产生进一步的加热，从而驱动热带天气系统并影响全球的风。但这种深层对流云很少孤立存在；它们几乎总是被组织成各种结构，从飑线和云团到热带风暴、飓风和超级云团；对流在时间尺度上的变化范围很广，从单个云元素（小时），到每天的周期，到大量的波浪，周期从季节性振荡到季节性振荡，可以在30-60天内传播到世界各地。因此，热带大气在巨大的空间和时间尺度上组织起来；它对气候系统的影响与随机或无组织湍流的影响大不相同，因此，如果要准确地再现现实世界，所有这些尺度都应该在计算机模型中表现出来。到目前为止，许多这些影响都必须通过一种称为参数化的过程，以一种高度简化的方式来表示。这试图在比模型中明确表示的尺度更小的尺度上模拟对流的影响。问题是，在整个云系统中，从几公里到几百公里都没有一个首选的尺度，这些尺度跨越了从“子网格”（因此需要参数化）到那些由模型解决的范围。即使有了现代超级计算机，在最新的气候模型中，从参数化到解析运动的转变也发生在100公里左右。在现实世界中，所有低于这个尺度的结构都是参数化的，所以在解决的问题和参数化的问题之间出现了完全人为的中断。为了使问题更加复杂，参数化假设无法解决的尺度上的组织对于确定对流的性质或其对大尺度流动的影响并不重要。但越来越多的证据表明，这给模型带来了各种各样的问题。几十年来，人们一直在研究对流参数化问题，但即使花费了这么多时间和精力，也没有找到完全令人满意的解决方案。因此，我们建议对这个问题采取激进但完全合乎逻辑的办法。现在有可能在包含上述所有重要尺度的非常大的区域上运行能够明确解析对流系统的模型（至少可以精确到大约1km的尺度）。这种云系统解析模型提供了一种新的工具，用于理解对流如何真正工作和组织，以及如何在气候模型中参数化对流。我们的建议将这些模型与来自卫星和地面的新数据联系起来，这些数据将使我们对云和降雨产生系统的演变有一个前所未有的认识。我们将把这种独特的建模和观测结合起来，研究被认为是天气和气候中最基本的问题之一。这项工作的结果将为开发新一代更精确的大气模型提供信息，这些模型将在气候预测和天气预报中得到应用。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A Parameterization of Convective Dust Storms for Models with Mass-Flux Convection Schemes

DOI：
10.1175/jas-d-14-0341.1
发表时间：
2015-04
期刊：
Journal of the Atmospheric Sciences
影响因子：
3.1
作者：
Florian Pantillon;P. Knippertz;J. Marsham;C. Birch
通讯作者：
Florian Pantillon;P. Knippertz;J. Marsham;C. Birch

The role of deep convection and nocturnal low-level jets for dust emission in summertime West Africa: Estimates from convection-permitting simulations.

夏季非洲夏季的深度对流和夜间低水平喷气机在尘埃排放中的作用：根据对流的模拟估计。

DOI：
10.1002/jgrd.50402
发表时间：
2013-05-27
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
影响因子：
4.4
作者：
Heinold, B.;Knippertz, P.;Marsham, J. H.;Fiedler, S.;Dixon, N. S.;Schepanski, K.;Laurent, B.;Tegen, I.
通讯作者：
Tegen, I.

The sensitivity of convective aggregation to diabatic processes in idealized radiative-convective equilibrium simulations

理想化辐射对流平衡模拟中对流聚集对非绝热过程的敏感性