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50吨星际尘埃进入地球大气层。灰尘颗粒以11至72 km/s的速度与空气分子相撞，导致大多数颗粒闪烁热量，融化和蒸发。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1970年代以来，使用基于地面的LiDAR技术观察到Na，Fe，Ca和Ca+层。最近，使用卫星上的光学仪器在全球基础上观察金属层，包括MG和MG+。解释这些大气观测的需求激发了对这些金属及其离子在大气中经历的反应以及随之而来的局部大气模型的发展的实验室研究。中层金属层是上层大气的化学和动力学的极为有用的探针。这是因为这些层仅由快速光化学过程控制，其宽度仅由快速的光化学过程控制，它们对诸如重力波和潮汐等动力学过程非常敏感，并且大气成分（例如O，H和O3）的变化。当夏季在高纬度时温度下降到150 k以下时，夜光云大约是83公里，由于冰表面上金属的摄入迅速，会导致金属层的大量耗竭。在高纬度的冬季，在极性涡流上的子午循环的收敛似乎会导致金属浓度大幅增加。太阳质子事件还会引起金属层的明显扰动。最后，控制层高度的化学反应在很大程度上是由大气压驱动的，因此该层高度对中间气氛中的二氧化碳气体（例如CO2和CH4）引起的全球冷却敏感。该提议的目的是生产第一个全球模型的四种金属 - 钠，铁，钙和镁。这些金属在中层中的行为都大不相同。我们将将这些金属的化学插入到最先进的一般循环模型，即整个大气化学气候模型（WACCM），该模型已在过去十年中在美国国家大气研究中心开发。该一般循环模型从地球表面延伸至140 km，其中包括与金属相互作用的所有中性和电离成分。为了准备该项目，我们最近在英国的一线国家超级计算服务Hector（高端计算Terascale资源）安装并运行WACCM。对金属层进行建模还需要输入每种金属从消融星际灰尘中注入大气的速率，这是高度，季节，纬度和时间的函数。这些注射率将使用我们的新化学消融模型与流星输入函数的天文学模型相结合来计算。项目专业的学生将首次使用Envisat上的Sciamachy仪器来检索FE和FE+观察的全球数据集。这将补充Fe的基于地面的LIDAR测量值。将金属层密度，峰高以及昼夜和季节性变异性的WACCM预测与观察数据库进行比较。 WACCM的中层风和温度也将与测量值进行比较。这些比较将使WACCM Mesosphere能够优化，例如通过更高的垂直分辨率和重力波的更好处理。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，作为未来观察的指南。最后，改进的模型将用于研究中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.