DRivers and Impacts of Ionospheric Variability with EISCAT-3D (DRIIVE)

在支持空间气象研究的日地科学中，最大的悬而未决的问题之一是：高纬度电离层如何在小范围内变化，以响应来自上方和下方的驱动？一个直接的实际后续问题将是：小规模过程对更大的上层大气环境有什么影响？这些问题的答案对于理解空间天气对社会的影响至关重要。英国气象局最近对空间天气预报业务进行了投资，并将空间天气列入国家风险登记册，这证明了这一领域对英国越来越重要。为了回答这些问题，我们需要了解在被称为中层-低热层-电离层(MLTI-75-200公里高度)的区域发生的过程及其如何影响更广泛的耦合电离层-上层大气系统。电离层和高层中性大气本质上是联系在一起的：一个扰动，另一个变化。这对我们的近地空间环境有影响，在近地空间环境中，大气密度的变化造成空间碎片轨道的变化，增加了不可预见的碰撞风险；随着地球空间变得更加拥挤，这是一种重大的自然灾害。空间天气通过摩擦焦耳加热和粒子能量沉积在改变这一地区方面发挥了很大作用，但不是唯一的重要驱动因素。低层大气中的天气推动了电离层的变化，这种变化可以与外部强迫相媲美，但其相对贡献远未被理解，因为这些过程没有得到充分的观察。了解这一贡献的另一个障碍是我们无法适当地解释小规模的变化，无论是从上到下驱动的。高层大气模型通常不能解决这种变异性，但我们知道，如果不这样做，就会导致对大气加热幅度的低估高达40%。这一加热过程既依赖于空间天气的驱动，也依赖于中性大气成分和动力学的变化。该项目将使用全新的下一代电离层雷达：位于芬诺斯坎迪亚北部的EISCAT-3D。这是由NERC资助的一部分。它能够对大体积的局部电离层成像，并在1-100公里的水平尺度上提供测量。它将是独一无二的，具有高垂直和时间分辨率以及电离层电场矢量的多点测量。雷达的视场将覆盖极光地带纬度的相当大一部分，以便在那里进行的测量结果可以应用于更广泛的区域。我们将利用雷达的独特能力来量化空间天气事件沉积到MLTI的能量，并测量从低层大气向上传播的小尺度波的影响。我们将使用一系列辅助仪器，包括新部署的光学设备，并确定中性和电离区域之间的耦合如何影响能量平衡。解决这些过程将使我们能够确定它们在高层大气加热中的作用。我们将使用E3D观测和综合的高层大气模式来确定和应用小范围变化引起的加热估计的修正方法。利用先进的模型，加上我们的观测结果，我们将确定小尺度如何影响地球东南部环境中的低空卫星碎片场。这个项目直接涉及NERCHight LIGHT主题机会公告中确定的两个优先领域(并涉及其他领域)，因此回答了关键问题：高纬度电离层如何在小尺度上对来自上方和下方的驱动做出反应？

One of the biggest unanswered questions in the solar-terrestrial science that underpins Space Weather research is:How does the high latitude ionosphere vary on small scales in response to driving from above and below?An immediate practical follow-on question would be: what are the impacts of small-scale processes to the larger upperatmosphere environment? The answers to these questions are essential for understanding how Space Weather impacts onsociety. This area is of growing importance to the UK, as evidenced by recent investment in operational Space Weatherforecasting at the Met Office and the inclusion of Space Weather in the National Risk Register.To answer these questions, we need to understand the processes that occur in the region known as the Mesosphere-Lower Thermosphere-Ionosphere (MLTI - 75-200 km altitude) and how they affect the wider coupled ionosphere-upperatmospheresystem. The ionosphere and upper neutral atmosphere are intrinsically linked: perturb one and the otherchanges. This has implications for our near-Earth space environment where variations in atmospheric density producechanges in the orbits of space debris, increasing the risk of unforeseen collisions; a significant natural hazard as Geospacegrows more crowded. Space Weather plays a big role in modifying this region through frictional Joule heating and particleenergy deposition but is not the only important driver. The weather in the lower atmosphere drives changes in theionosphere that can be comparable to external forcing, but the relative contribution is far from understood, as theprocesses are under-observed. Another barrier to knowing that contribution is our inability to properly account for smallscale variability, whether driven from above or below. Upper atmosphere models typically do not resolve this variability, yetwe know that not doing so leads to underestimates of the magnitude of atmospheric heating by as much as 40%. Thisheating is a process that relies both on space weather driving and changes in the neutral atmosphere composition anddynamics.This project will use the brand new, next generation ionospheric radar: EISCAT-3D, located in northern Fennoscandia. Thisis part funded by NERC. It is capable of imaging a large volume of the local ionosphere and providing measurements onhorizontal scales of 1-100 km. It will be unique with high vertical and temporal resolution and multipoint measurements ofthe ionospheric electric field vector. The field of view of the radar will cover a decent proportion of the auroral zone inlatitude, such that results from the measurements made there can be applied to the wider region.We will use the unique capabilities of the radar to quantify the energy that is deposited into the MLTI from space weatherevents and also measure the impact of small-scale waves that propagate upwards from the lower atmosphere. We will usea range of support instrumentation, including newly deployed optics, and determine how the coupling between the neutraland ionized regimes affect the energy balance. Resolving these processes will let us establish their role in upperatmospheric heating.We will use the E3D observations together with comprehensive upper atmosphere models to determine and apply methodsof correcting estimates of heating due to the small-scale changes. Using advanced models with inputs informed by theresults of our observations we will determine how the small-scales affect the low altitude satellite debris field in the Earth'souter environment.This Project directly addresses two of the priority areas (and touches on others) that have been identified in the NERCHighlight Topic Announcement of Opportunity, and so answers the key question: How does the high latitude ionospherevary on small scales in response to driving from above and below?