EISCAT_3D: Fine-scale structuring, scintillation, and electrodynamics (FINESSE)

英国和世界其他地方一样，越来越依赖于技术系统，包括卫星通信、全球定位系统和电网，这些系统都面临着太空天气的风险。许多空间天气灾害起源于电离层，即海拔90公里及以上的电离大气层的上层，在那里，地球磁场引导的太阳风可以造成各种不可预测的有害影响。它引起电流流动，使大气加热，这一过程被称为焦耳加热，这反过来又会导致大气向上膨胀，对卫星产生阻力，从而使它们的轨道更难预测，并缩短它们的寿命。它产生了电离层的水平运动，通过摩擦改变了热层中的中性风。它产生了极光，与来自上方磁层的粒子降水有关，这改变了电离层的结构。此外，它还会引起等离子体的不稳定性，导致电离层变得波纹状，从而散射卫星发出的无线电波，从而干扰通信和GPS。虽然这种空间天气灾害的大尺度分布在全球环流模式中相对较好地再现了，但在小于模式网格的空间尺度上发生的物理现象却知之甚少，这阻碍了预报的改进。FINESSE项目将利用一种新的、独特的、由nerc资助的非相干散射雷达系统EISCAT_3D，该系统位于斯堪的纳维亚半岛北部，用于研究这些亚网格空间天气尺度。EISCAT_3D将能够以前所未有的空间和时间分辨率确定电离层结构，这些电离层结构在水平方向大约200公里，垂直方向大约800公里，从而对导致空间天气影响的过程进行成像。FINESSE还将利用下一代相干散射雷达来测量电离层运动，三台中性风成像仪来测量热层和电离层之间的相互作用，三台全天极光相机来观察上方磁层的降水区域，一台精细尺度极光成像仪来观察空间和时间尺度上的极光结构，甚至比EISCAT_3D可以探测的还要精细。以及一个射电望远镜和GPS接收器网络，以观察来自宇宙源和卫星的无线电信号的闪烁。FINESSE的主要目的如下。1)确定焦耳加热的小规模来源，将其置于极地极光扰动的大背景下，确定焦耳加热与卫星阻力之间的联系，并将这些结果纳入改进预报模型。2)确定小规模电离层结构的原因，并了解这是如何导致无线电信号闪烁的。3)在最小的时空尺度上探索极光动力学，以了解磁层和电离层之间耦合的物理特性，极光过程在电离层和大气的加热和结构中所起的作用，以及导致亚暴（向夜侧极光电离层爆炸释放能量）的不稳定性。FINESSE将与空间天气预报员和其他利益相关者联系，传播对产生空间天气危害的小规模过程的更深入了解，并将其转化为对英国的重大经济利益。

The UK along with the rest of the world is becoming increasingly dependent on technological systems, including satellite communications, global positioning systems, and power grids, that are at risk from space weather. Many space weather hazards originate in the ionosphere, the ionised upper part of the atmosphere at altitudes of 90 km and above, where solar wind energy channelled by the Earth's magnetic field can cause a variety of unpredictable and deleterious effects. It causes electrical currents to flow, which heat the atmosphere in a process known as Joule heating, which in turn can cause the atmosphere to expand upwards, producing drag on satellites, hence making their orbits harder to predict and reducing their lifetimes. It produces horizontal motions of the ionosphere which modify the neutral winds in the thermosphere through friction. It produces the auroras, associated with particle precipitation from the magnetosphere above, which modify the ionospheric structure. Moreover, it gives rise to plasma instabilities which cause the ionosphere to become corrugated, scattering radio waves from satellites consequently disturbing communications and GPS. Although the large-scale distribution of such space weather hazards is relatively well reproduced in global circulation models, the physics occurring on spatial scales smaller than the model grid is poorly understood, which holds back improvements in forecasting. The FINESSE project will exploit a new and unique NERC-funded incoherent scatter radar system, EISCAT_3D, located in northern Scandinavia, to study these sub-grid space weather scales. EISCAT_3D will be able to determine the ionospheric structure in a box roughly 200 km to a side horizontally and 800 km vertically, at an unprecedented spatial and temporal resolution, to image the processes leading to space weather effects. FINESSE will also exploit a next-generation coherent scatter radar to measure ionospheric motions, three neutral wind imagers to measure the interaction between the thermosphere and the ionosphere, three all-sky auroral cameras to view regions of precipitation from the magnetosphere above, a fine-scale auroral imager to observe auroral structures on spatial and temporal scales even finer than EISCAT_3D can probe, and a radio telescope and network of GPS receivers to look at the scintillation of radio signals from both cosmic sources and satellites. The main aims of FINESSE are as follows. 1) To determine the small-scale sources of Joule heating, to place these within the context of the larger picture of polar auroral disturbances, to determine the link between Joule heating and satellite drag, and to incorporate these results to improve forecast models. 2) To determine the cause of small-scale ionospheric structuring, and to understand how this leads to scintillation of radio signals. 3) To probe auroral dynamics at the very smallest temporal and spatial scales to understand the physics of coupling between the magnetosphere and ionosphere, the role auroral processes play in heating and structuring the ionosphere and atmosphere, and the instability that leads to substorms (explosive releases of energy into the nightside auroral ionosphere). FINESSE will liaise with space weather forecasters and other stakeholders to disseminate this greater understanding of small-scale processes in producing space weather hazards and to translate it into significant economic benefit to the UK.