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

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.