NSFGEO-NERC: Wave-Induced Transport of Chemically Active Species in the Mesosphere and Lower Thermosphere (WAVECHASM)

NSFGEO-NERC：中层和低层热层中化学活性物质的波诱导传输（WAVECHASM）

基本信息

批准号：
NE/T006749/1
负责人：
John Plane
金额：
$ 58.11万
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：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FT006749%2F1
关键词：
NSFGEO NERC Wave Induced Transport

项目摘要

Tides, planetary waves and gravity waves play major roles in establishing the thermal structure and general circulation of the mesosphere/lower thermosphere (MLT) region of the atmosphere (70 - 120 km). For example, the summer mesopause region is the coldest place in the atmosphere due to the meridional circulation induced by gravity wave dissipation. Less well known and understood are the equally important roles that waves play in vertical constituent transport, which is a fundamental atmospheric process that has profound effects on the chemistry and composition of the atmosphere below the turbopause at around 105 km.Atmospheric gravity waves are generated by a variety of mechanisms (e.g. orographic forcing, convection, wind shears) in the troposphere and stratosphere. As the waves propagate upwards their amplitudes grow because of the exponentially falling air pressure, causing a fraction of the waves to become superadiabatic and "break". Wave-breaking is the main source of turbulence in the MLT. A final fraction of the wave spectrum can survive and penetrate into the thermosphere.Waves, and the turbulence they generate, contribute to vertical constituent transport by inducing large-scale advection, eddy transport through turbulent mixing, dynamical transport associated with dissipating, non-breaking waves and chemical transport associated with perturbed chemistry. Recently, compelling evidence has emerged that dynamical and chemical transport is significantly underestimated in global chemistry-climate models. The vertical fluxes of Na and Fe atoms, produced from ablating meteors, have recently been measured by the ground-based lidar technique and are 5 to 10 times larger than in a state-of-the-art climate model. The higher fluxes are supported by astronomical models of dust evolution in the solar system. There is also a significant deficit in the modelled concentrations of O atoms and O3 in the MLT. The most likely reason for these apparent model deficiencies is that a fraction of the gravity wave spectrum is not explicitly captured in models because the wavelengths are smaller than the model horizontal grid-scale (typically > 100 km), and these small waves make a major contribution to vertical transport. The computational cost of increasing the horizontal resolution to include small-scale wave transport effects directly in global models - especially incorporating chemistry - is currently prohibitive.The aim of the WAVECHASM project is to produce a parameterization which can be used to calculate all components of vertical transport in a global model. The project will proceed in four stages. First, we will run a global model with the facility to increase the horizontal resolution regionally down to ~ 14 km, in order to demonstrate the importance of short wavelength waves. In the second step we will parameterise a recent mathematical treatment of dynamical and chemical transport, which shows that these transport terms can be computed in a relatively straightforward way from the wave spectrum in each model grid box. For the third stage we will assemble a data-base of measurements of the vertical fluxes of Na, Fe (in some cases) and heat at 6 lidar stations, the Na density at 16 stations, and satellite measurements of Na and other MLT constituents (e.g. O, O3, NOx, CO2). In the final stage, the new global model with wave transport will be run for 20 years (covering the period of these observations), to study the impact of wave transport on the global distribution and seasonal variations of the important, chemically active species. Once the vertical flux of Na atoms can be reconciled with the abundance of Na in the layer around 90 km, we will obtain an accurate estimate of the amount of interplanetary dust entering the atmosphere, and thus constrain astronomical models of dust evolution in the solar system and improve our understanding the impacts of this dust throughout the atmosphere.

潮汐，行星波和重力波在建立大气中米层/下热层（MLT）区域的热结构和一般循环方面起着重要作用（70-120 km）。例如，由于重力波耗散引起的子午循环，夏季间膜区域是大气中最冷的位置。鲜为人知和理解的是波在垂直组成运输中发挥的同样重要的作用，这是一个基本的大气过程，对涡轮上的大气和大气组成的影响很大，在105 k.Atmospheric Gravity Wave中是由涡轮上的大气组成。对流层和平流层中的多种机制（例如，对流，对流，风剪）。随着波浪向上传播，由于气压呈指数下降，它们的幅度生长，导致一部分波成为超级绝热和“破裂”。波动是MLT中湍流的主要来源。波谱的最后一部分可以生存并穿透热层。波和它们产生的湍流，通过诱导大规模的对流，通过湍流混合，与消散，无破裂的动力运输有关与扰动化学相关的波和化学转运。最近，有令人信服的证据表明，在全球化学气候模型中，动力运输和化学运输被显着低估。最近通过基于地面的LiDAR技术测量了由消融流星产生的Na和Fe原子的垂直通量，并且是最先进的气候模型中的5至10倍。太阳系中尘埃演化的天文学模型支持了较高的通量。 MLT中的O原子和O3的建模浓度也存在明显的缺陷。这些明显模型缺陷的最可能原因是，在模型中未明确捕获重力波谱的一部分，因为波长小于模型的水平网格尺度（通常> 100 km），并且这些小波使主要波浪成为主要的波浪。对垂直运输的贡献。目前，在全球模型（尤其是化学融合）中，将水平分辨率提高到包括小规模波传输效应的计算成本是过敏的。WaveChasm项目的目的是产生一个参数化，可用于计算垂直的所有组件全球模型中的运输。该项目将在四个阶段进行。首先，我们将运行一个具有该设施的全局模型，以将水平分辨率从区域下降到约14 km，以证明短波长波的重要性。在第二步中，我们将对动态和化学转运的最新数学处理进行参数，这表明可以从每个模型网格盒中的波谱以相对直接的方式计算这些传输项。对于第三阶段，我们将组装Na，Fe（在某些情况下）和热量的垂直通量的测量数据库，在6个激光雷达站，Na密度在16个站点，以及Na和其他MLT成分的卫星测量值（例如O，O3，NOX，CO2）。在最后阶段，新的带有波传输的全球模型将运行20年（涵盖了这些观察的时期），以研究波传输对重要的化学活性物种的全球分布和季节变化的影响。一旦Na原子的垂直通量可以与90 km左右的Na的丰度进行调和，我们将获得对进入大气的星际尘埃的准确估计，从而限制了太阳系中尘埃演化的天文学模型并提高我们的理解在整个大气中的影响。