Continuum Absorption at Visible and Infrared Wavelengths and its Atmospheric Relevance (CAVIAR)

可见光和红外波长的连续吸收及其大气相关性 (CAVIAR)

基本信息

批准号：
NE/D010764/1
负责人：
Keith Shine
金额：
$ 52.06万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD010764%2F1
关键词：
Continuum Absorption Visible Infrared Wavelengths

项目摘要

Water vapour is the most important greenhouse gas in the Earth's atmosphere. Because of its complex structure, it is unusual in that it absorbs energy across a wide range of wavelengths from the ultra-violet, to the microwave. Infrared absorption by water vapour is of particular significance. It causes a large part of the natural greenhouse effect which makes the Earth habitable, hence impacting on the present day climate. It also plays an important role in climate change. If the Earth warms, for example due to increases in CO2, water vapour concentrations increase; since water vapour is itself a greenhouse gas, this leads to a positive feedback which, models indicate, approximately doubles the warming. Unfortunately, understanding of the absorbing properties of water vapour is currently inadequate. Water vapour absorbs radiation in two ways. The first is in narrow wavelength regions (spectral lines) for which understanding is relatively good. The second is slowly varying absorption over broad spectral regions (the continuum). It is the understanding of this continuum absorption which is the subject of this proposal. The existence of the continuum has been known for decades, but an understanding of its cause, and its characteristics, is a source of controversy. One theory is that it is due to cumulative small contributions from thousands of spectral lines; an alternative, but not necessarily exclusive, theory is that it is due to absorption by pairs of weakly bound water molecules (the water dimer) and related species. Currently, most computer models used in weather forecasting, climate prediction, and to retrieve data from satellite observations, use one particular representation of the continuum developed over the past twenty years. This representation has served the community well. However, it lacks a firm theoretical basis and has only been verified using observations for a quite narrow range of wavelengths and atmospheric conditions; additionally, these observations have been made by different groups at different times and their comparability is difficult to assess. This limits confidence in its use, particularly as climate, and hence atmospheric conditions, change. Developments in the theory of continuum absorption, as well as advances in instrumentation, mean that it is timely for a concerted effort to improve our understanding and characterisation of the continuum. We bring together a consortium of 8 leading UK groups with established expertise in the theory of water vapour absorption, in the use of state-of-the-art measurement techniques in both the laboratory and the atmosphere, and in climate modelling. The programme of research involves several components. 1 Advanced calculations of vibrations and rotations of the water dimer, which will allow a better prediction of its absorption properties and its contribution to the continuum. 2 The use of a state-of-the-art laboratory instrumentation enabling the measurement of the continuum over an unprecedentedly broad range of wavelengths and conditions; an alternative technique, capable of measuring relatively weak absorption at very high precision will be deployed for detailed studies in narrower wavelength regions. 3 Field campaigns, which will use a mixture of well-calibrated ground and aircraft based instruments, and will characterise the continuum over a broad range of wavelengths under real atmospheric conditions. We propose two campaigns: one in south-west England and one at a high mountain site in Europe. This will allow measurements to be made under very different atmospheric conditions. 4 Synthesis of the results from the theory, laboratory measurements and field campaigns, drawing them together into a common framework. 5 Understanding of the impact of the new results on our understanding of present-day climate and climate change. 6 Development of a representation of the continuum data in a form that can be readily used by other researchers.

水蒸气是地球大气中最重要的温室气体。由于其复杂的结构，它的不同寻常之处在于它吸收从紫外线到微波的各种波长的能量。水蒸气吸收红外线具有特别重要的意义。它造成了很大一部分自然温室效应，使地球适合居住，从而影响了当今的气候。它还在气候变化中发挥着重要作用。如果地球变暖，例如由于二氧化碳增加，水蒸气浓度就会增加；由于水蒸气本身就是一种温室气体，这会产生正反馈，模型表明，这种反馈大约会使变暖程度增加一倍。不幸的是，目前对水蒸气吸收特性的了解还不够。水蒸气以两种方式吸收辐射。第一个是在窄波长区域（光谱线），对此理解相对较好。第二个是在宽光谱区域（连续谱）上缓慢变化的吸收。对这种连续吸收的理解正是本提案的主题。连续体的存在几十年来一直为人所知，但对其成因及其特征的理解却存在争议。一种理论认为，这是由于数千条谱线的累积微小贡献造成的。另一种但不一定是排他性的理论是，这是由于弱结合水分子对（水二聚体）和相关物质的吸收所致。目前，大多数用于天气预报、气候预测以及从卫星观测中检索数据的计算机模型都使用过去二十年开发的连续体的一种特定表示。这一代表为社区提供了良好的服务。然而，它缺乏坚实的理论基础，并且仅通过对相当窄的波长范围和大气条件的观测来验证；此外，这些观察结果是不同群体在不同时间做出的，很难评估其可比性。这限制了对其使用的信心，特别是当气候以及大气条件发生变化时。连续介质吸收理论的发展以及仪器仪表的进步意味着现在需要共同努力来提高我们对连续介质的理解和表征。我们汇集了由 8 个英国领先团体组成的联盟，他们在水蒸气吸收理论、在实验室和大气中使用最先进的测量技术以及气候建模方面拥有成熟的专业知识。该研究计划涉及几个组成部分。 1 对水二聚体的振动和旋转进行高级计算，这将有助于更好地预测其吸收特性及其对连续体的贡献。 2 使用最先进的实验室仪器，能够在前所未有的广泛波长和条件下测量连续谱；将采用一种替代技术，能够以非常高的精度测量相对较弱的吸收，以在较窄波长区域进行详细研究。 3 现场活动将使用经过良好校准的地面和机载仪器，并在真实大气条件下表征广泛波长范围内的连续谱。我们提出两项活动：一项在英格兰西南部，一项在欧洲的高山地区。这将允许在非常不同的大气条件下进行测量。 4 综合理论、实验室测量和现场活动的结果，将它们整合到一个共同框架中。 5 了解新结果对我们了解当今气候和气候变化的影响。 6 以其他研究人员可以轻松使用的形式开发连续统数据的表示形式。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Analysis of far-infrared spectral radiance observations of the water vapor continuum in the Arctic

北极水汽连续体远红外光谱辐射观测分析

DOI：
http://dx.10.1016/j.jqsrt.2015.01.001
发表时间：
2015
期刊：
Journal of Quantitative Spectroscopy and Radiative Transfer
影响因子：
2.3
作者：
Fox C
通讯作者：
Fox C

Validation of the far-infrared foreign-broadened water vapour continuum from airborne field campaign measurements

通过机载现场活动测量验证远红外外展水汽连续谱

DOI：
发表时间：
2012
期刊：
影响因子：
0
作者：
Beeby Ralph
通讯作者：
Beeby Ralph

The Cirrus Coupled Cloud-Radiation Experiment-II

卷云耦合云辐射实验-II

DOI：
http://dx.10.1364/hise.2016.htu2f.3
发表时间：
2016
期刊：
影响因子：
0
作者：
Murray J
通讯作者：
Murray J

Recent advances in measurement of the water vapour continuum in the far-infrared spectral region.

远红外光谱区水蒸气连续谱测量的最新进展。

DOI：
http://dx.10.1098/rsta.2011.0263
发表时间：
2012
期刊：
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
影响因子：
0
作者：
Green PD
通讯作者：
Green PD

Estimating Far Infrared Surface Emissivity over Greenland from the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS)

利用对流层机载傅里叶变换光谱仪 (TAFTS) 估算格陵兰岛的远红外表面发射率