The main science goal of this project is to improve our understanding of the electromagnetic coupling between Earth's ionosphere and magnetosphere. The distributions of the high latitude convection electric fields, field aligned currents (FAC) and conductances will be determined with improved spatial and temporal resolution using a unique set of tools. The resulting distributions will be used to investigate the following M-I coupling science questions:
1) What are the basic characteristics of the FACs?
2) How does the FAC pattern develop and grow during storms and substorms?
3) What is the relationship between electric potential and FACs during saturation events?
4) What do FAC tell us about variability in the ion and electron plasma sheets?
5) What is the distribution of magnetospheric energy input, and what are consequences for the Ionosphere-Thermosphere system?
The new tool to describe high latitude electrodynamics will be developed by combining a first-principles model of the I/T system (the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM)) with a data-based objective analysis model of ionospheric electron density (Ionospheric Data Assimilation Three Dimensional (IDA3D)), and the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) algorithm. TIMEGCM and IDA3D will be combined to provide global conductance estimates that will be assimilated by AMIE. AMIE assimilates various other electrodynamic datasets to obtain global maps of the high latitude potential pattern, conductance, and field aligned currents. AMIE output fields (convection and particles) will in turn be used to drive the TIMEGCM, predicting global responses to the M-I coupling specification. There is currently a disagreement between the values of conductances obtained from AMIE, TIMEGCM, IDA3D, and satellite Far Ultra-violet (FUV) imagers such as GUVI and IMAGE. The TIMEGCM conductance generally agrees well with AMIE when it is driven by AMIE fields. The conductances will be validated by comparison with data from the Sondrestrom Incoherent Scatter radar. We will compare the TIMEGCM ionization rates with those from the GLOW auroral code for given particle characteristics. The proposal brings together a broad group of magnetosphere, I-T, and electrodynamics experts to address the proposed science questions. This work represents an important contribution to the study of magnetosphere-ionosphere coupling, which is a key area of study as we seek to understand the chain of processes that govern solar-terrestrial relations and space weather. Finally, this study may also suggest improvements in the various global geospace models currently under development such as CISM (Center for Integrated Space-weather Modeling), which represent the distillation of the community's understanding of solar-terrestrial coupling.
The proposed study will advance discovery and understanding while also promoting teaching, training and learning. A significant portion of the research proposed here will be performed by a female graduate student at the University of Texas at San Antonio. UTSA is a minority serving institution. A student at UC Berkeley will also be partially funded by this project. The proposed activity will also benefit society in helping to understand variability in the geospace environment, which affects satellite lifetimes and orbits, and technological systems such as navigation, communications and surveillance systems.
