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Multi-scale Modelling of Mesospheric Metals (4M)

中层金属的多尺度建模 (4M)

基本信息

批准号：
NE/G019487/1
负责人：
John Plane
金额：
$ 54.61万
依托单位：
University of Leeds
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%2FG019487%2F1
关键词：
Multi scale Modelling Mesospheric Metals

项目摘要

Roughly 50 tonnes of interplanetary dust enters the earth's atmosphere every day. The dust particles collide with air molecules at speeds between 11 and 72 km/s, causing most of the particles to flash heat, melt and evaporate. This produces metal atoms which then appear in layers between about 75 and 110 km. The Na, Fe, Ca and Ca+ layers have been observed since the 1970s using the ground-based lidar technique. Recently it has become possible to observe the metal layers, including Mg and Mg+, on a global basis using optical instruments on satellites. The need to explain these atmospheric observations has stimulated laboratory studies of the reactions which these metals and their ions undergo in the atmosphere, and the consequent development of local scale atmospheric models. The mesospheric metal layers are extremely useful probes of the chemistry and dynamics of the upper atmosphere. This is because the layers, whose widths of just a few km are controlled by fast photochemical processes, are very responsive to dynamical processes such as gravity waves and tides, and changes in atmospheric constituents such as O, H and O3. Noctilucent clouds, which form around 83 km when the temperature falls below 150 K during summer at high latitudes, cause substantial depletion of the metal layers because of rapid uptake of the metals on the ice surfaces. During winter at high latitudes, convergence of the meridional circulation over the polar vortex appears to cause a substantial increase in the metal concentrations. Solar proton events also cause significant perturbations to the metal layers. Lastly, the chemistry which controls the heights of the layers is largely driven by atmospheric pressure, and so the layer heights are sensitive to global cooling caused by increasing greenhouse gases such as CO2 and CH4 in the middle atmosphere. The objective of this proposal is to produce the first global model of four metals - sodium, iron, calcium and magnesium. These metals all behave quite differently in the mesosphere. We will insert the chemistry of these metals into a state-of-the-art general circulation model, the Whole Atmosphere Chemistry Climate Model (WACCM), which has been developed at the US National Center for Atmospheric Research over the past decade. This general circulation model extends from the earth's surface to 140 km, and includes all the neutral and ionized constituents with which the metals interact. In preparation for this project, we have recently installed and run WACCM on the UK's front-line national supercomputing service HECToR (High-End Computing Terascale Resource). Modelling the metal layers also requires as input the rates at which each metal is injected into the atmosphere from ablating interplanetary dust, as a function of height, season, latitude and time-of-day. These injection rates will be calculated using our new Chemical Ablation Model, combined with an astronomical model of the meteor input function. A project student will retrieve, for the first time, a global data set of Fe and Fe+ observations, using the SCIAMACHY instrument on ENVISAT. This will supplement the ground-based lidar measurements of Fe. The WACCM predictions of the metal layer densities, peak heights, and diurnal and seasonal variability will be compared with the observational data base. The WACCM mesospheric winds and temperatures will also be compared with measurements. These comparisons will enable the WACCM mesosphere to be optimised e.g. through higher vertical resolution and better treatment of gravity waves. We will then investigate the likely impact of the solar cycle and climate change on the distributions of all four metals, for instance as a guide to future observations. Finally, the improved model will be used to study the impact of the mesosphere on stratospheric ozone and climate.

每天大约有 50 吨行星际尘埃进入地球大气层。尘埃颗粒以 11 至 72 公里/秒的速度与空气分子碰撞，导致大部分颗粒瞬间发热、熔化并蒸发。这会产生金属原子，然后出现在约 75 至 110 公里之间的层中。自 20 世纪 70 年代以来，人们一直使用地面激光雷达技术来观测 Na、Fe、Ca 和 Ca+ 层。最近，使用卫星上的光学仪器在全球范围内观察金属层（包括 Mg 和 Mg+）已成为可能。解释这些大气观测结果的需要刺激了对这些金属及其离子在大气中发生的反应的实验室研究，以及随后局部尺度大气模型的发展。中层金属层是高层大气化学和动力学极其有用的探针。这是因为这些层的宽度只有几公里，由快速光化学过程控制，对重力波和潮汐等动力过程以及 O、H 和 O3 等大气成分的变化非常敏感。夜光云在高纬度地区夏季温度低于 150 K 时形成约 83 公里，由于冰表面金属的快速吸收，导致金属层大量消耗。在高纬度地区的冬季，极涡上方经向环流的汇聚似乎会导致金属浓度大幅增加。太阳质子事件也会对金属层造成显着的扰动。最后，控制层高度的化学物质很大程度上是由大气压力驱动的，因此层高度对中层大气中二氧化碳和甲烷等温室气体增加引起的全球变冷很敏感。该提案的目标是生产第一个四种金属（钠、铁、钙和镁）的全球模型。这些金属在中间层的表现都截然不同。我们将把这些金属的化学性质插入到最先进的大气环流模型中，即全大气化学气候模型（WACCM），该模型是美国国家大气研究中心在过去十年中开发的。这个大气环流模型从地球表面延伸到 140 公里，包括与金属相互作用的所有中性和电离成分。为了准备这个项目，我们最近在英国一线国家超级计算服务 HECToR（高端计算万亿级资源）上安装并运行了 WACCM。对金属层进行建模还需要输入每种金属通过烧蚀行星际尘埃注入大气层的速率，作为高度、季节、纬度和一天中时间的函数。这些注入率将使用我们新的化学烧蚀模型结合流星输入函数的天文模型来计算。项目学生将使用 ENVISAT 上的 SCIAMACHY 仪器首次检索 Fe 和 Fe+ 观测的全球数据集。这将补充铁的地面激光雷达测量。 WACCM 对金属层密度、峰值高度以及昼夜和季节变化的预测将与观测数据库进行比较。 WACCM 中层风和温度也将与测量结果进行比较。这些比较将使 WACCM 中间层得到优化，例如通过更高的垂直分辨率和更好地处理重力波。然后，我们将研究太阳周期和气候变化对所有四种金属分布的可能影响，例如作为未来观测的指南。最后，改进的模型将用于研究中间层对平流层臭氧和气候的影响。

项目成果

期刊论文数量（9）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

First global observations of the mesospheric potassium layer

DOI：
10.1002/2014gl060801
发表时间：
2014-08
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
E. Dawkins;J. Plane;M. Chipperfield;W. Feng;J. Gumbel;J. Hedin;J. Höffner;J. Friedman
通讯作者：
E. Dawkins;J. Plane;M. Chipperfield;W. Feng;J. Gumbel;J. Hedin;J. Höffner;J. Friedman

Diurnal variation of the potassium layer in the upper atmosphere.