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A study of clear sky closure study using high resolution far-IR spectra from the high arctic

利用北极高纬度高分辨率远红外光谱进行晴空闭合研究

基本信息

批准号：
NE/H007717/1
负责人：
Juliet Pickering
金额：
$ 14.27万
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：
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%2FH007717%2F1
关键词：
study clear sky closure using

项目摘要

The Earth's energy balance is in equilibrium, that is to say, an equal amount of energy is absorbed and emitted, The Sun is the source of all energy for the Earth, heating the planet via sunlight, warming the surface and this energy is emitted back into space as heat. A simple calculation can be made to estimate the surface temperature needed to preserve this equilibrium, and is about 255K, or -18degC. The presence of gases in the atmosphere that can absorb heat (greenhouse gases, such as water vapour and carbon dioxide), affects this basic equilibrium, meaning that it isn't generally the surface, but a layer of the atmosphere some distance above our heads that releases the energy to space; keeping the surface warmer than we would initially expect, and habitable for us humans. Once we look into what actually happens in more detail, this picture becomes very complicated. For instance, whether the surface is covered by ocean, desert, forests or snow makes a big difference, as does the concentration of greenhouse gases through the depth of the atmosphere and the amount, height and type of any cloud. Generally speaking, in the tropics more energy is absorbed than is emitted back to space; the winds and oceans transport this excess heat north and south towards the poles. At the other extreme, the Arctic region absorbs very little sunlight, and emits more energy to space than it receives. There is highly reflective snow and ice in the Arctic region and because it is so cold, the air is relatively dry compared to lower latitudes. With water vapour being one of the major greenhouse gases, the Arctic doesn't trap the heat as well as in the tropics. In some places and meteorological situations, parts of the heat (infra-red) spectrum of the atmosphere become transparent, allowing the surface to cool directly to space, removing some of the warming effect of the atmosphere. Where this happens is very interesting for scientists who try to understand the subtle mechanisms that control the loss of heat from the atmosphere. Using the Imperial College high resolution far infrared spectrometer (TAFTS), together with the US spectrometer (AERI-ER) we have taken measurements of the whole infrared spectrum from a site in the high arctic, where these rare conditions occur. The site was the United States Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) site in Barrow, Alaska, in the spring of 2007. These measurements allow us to look up through these transparent windows to study the interaction between the greenhouse gases and thermal radiation in these dry conditions. These measurements were funded by the US ARM program, with initial analysis having shown that the data is of good quality and of scientific use. We now wish to analyse this data to take the full scientific benefit and impact from it. In addition to the infrared measurements of spectral radiances, we have the auxiliary data, which defines the state of the atmosphere, both the temperature and water vapour profile throughout the atmosphere, evidence for the lack of clouds etc. Using these datasets we are aiming to be able to better quantify the strength of the water vapour absorption lines, and the underlying absorption by water vapour, known as the continuum absorption. We will also use our results and models to investigate the cooling to space in the far infrared. This work will improve our understanding of the atmosphere, with many applications in radiation components of global climate models, and is expected to give greater accuracy in atmospheric models.

地球的能量平衡是平衡的，也就是说，吸收和释放等量的能量，太阳是地球所有能量的来源，通过阳光加热地球，使表面变暖，这些能量以热量的形式被释放回太空。一个简单的计算可以估算出保持这种平衡所需的表面温度，大约是255 K或-18 ℃。大气中存在的气体可以吸收热量（温室气体，如水蒸气和二氧化碳），影响这种基本平衡，这意味着它通常不是表面，而是在我们头顶上方一定距离的大气层，将能量释放到太空;保持表面比我们最初预期的要温暖，适合我们人类居住。一旦我们更详细地观察实际发生的事情，这个画面就会变得非常复杂。例如，地表是否被海洋、沙漠、森林或积雪覆盖，以及大气层深处温室气体的浓度和任何云的数量、高度和类型，都会产生很大的差异。一般来说，在热带地区，吸收的能量多于释放回太空的能量;风和海洋将这些多余的热量向南北两极输送。在另一个极端，北极地区吸收的阳光很少，向太空发射的能量多于接收的能量。在北极地区有高度反射的雪和冰，因为它是如此寒冷，与低纬度地区相比，空气相对干燥。由于水蒸气是主要的温室气体之一，北极不像热带地区那样吸收热量。在某些地方和气象条件下，大气的部分热（红外）光谱变得透明，使表面直接冷却到太空，消除了大气的一些变暖效应。对于试图了解控制大气热量损失的微妙机制的科学家来说，这种情况发生的地方非常有趣。使用帝国理工学院的高分辨率远红外光谱仪（TAFTS），与美国光谱仪（AERI-ER）一起，我们已经从高北极地区的一个地点，在这些罕见的条件下发生的整个红外光谱进行了测量。该站点是2007年春季位于阿拉斯加州巴罗的美国能源部大气辐射测量站点。这些测量使我们能够透过这些透明的窗户向上看，以研究在这些干燥条件下温室气体和热辐射之间的相互作用。这些测量由美国ARM计划资助，初步分析表明数据质量良好，具有科学用途。我们现在希望分析这些数据，以充分利用其科学效益和影响。除了光谱辐射的红外测量外，我们还有辅助数据，这些数据定义了大气的状态，包括整个大气的温度和水蒸气分布，使用这些数据集，我们的目标是能够更好地量化水蒸气吸收线的强度，以及水蒸气的潜在吸收，称为连续吸收。我们还将使用我们的结果和模型来研究远红外线中的空间冷却。这项工作将提高我们对大气的认识，在全球气候模型的辐射部分有许多应用，并有望提高大气模型的准确性。