# Presentation: 003367

## Establishing a Magnetospheric-Ionospheric Roadmap

_***Harlan E. Spence***_*** ***
***Boston University ***
***Department of Astronomy and***
***Center for Space Physics***

***Seventh Annual Huntsville 2000 Workshop , Callaway Gardens, Pine Mountain, Georgia ******October 30 -November 3, 2000***

## Empirical Magnetic field mapping 

- Empirical Magnetic field mapping
- Detailed spectral particle mapping
- Distinct features in auroral Emission/particle precipitation associated with distinct magnetospheric phenomena
- Morphological particle population mapping
- Global ionospheric convection observations compared With global magnetospheric simulation flows

## Where are we? 

- The magnetosphere-ionosphere system is vast, dynamic, and complex
- Ultimately, dense arrays of satellites simultaneously measuring the important state variables of the plasma are needed to understand the coupled MI system – a future direction
- The ionosphere already provides a convenient location where synoptic studies (flows, precipitation, currents, aurora, etc.) are conducted.
- However, basic uncertainties remain on how to relate these globally-measured features with associated magnetospheric processes.
- Here I review some of the strategies aimed at establishing these linkages
- Successes and limitations will be highlighted.

## Establishing a Magnetospheric-Ionospheric Roadmap

- A Richly historic topic that would be difficult to review comprehensively in this talk – I’ll discuss mostly recent ideas instead and use representative examples (so my apologies in advance)
- A critically important but elusive issue, elusive owing to the complexities of the mapping and the inherent time-dependencies that complicate associations
- A problem that grows more imperative as we seek understanding of the intimately coupled global ionosphere-magnetosphere as a system
- Progress is being made on many fronts and that is helping to define the next class of major missions

## Some Problems Associated with MI Cartography

- The ionospheric Resistive scale length Inherently limits visibility of magnetospheric features – It defines the minimum Magnetospheric feature in  auroral features (~!00km)
- The auroral accelerator decouples the M-I system just when it gets interesting! – Strong parallel potentials form in regions of strong parallel current– the ionospheric “screen” can be distorted and field lines can be far from equipotentials; auroral emissions can also be misleading
- Inductive electric fields are significant and also confound mappings – It is extremely dangerous to ignore time variations of the magnetic field
- Incomplete particle observations in angle and/or energy can lead to unresolvable ambiguities; multipoint observations help resolve the other difficulty of space/time separation

## Empirical Global Magnetic Field Mapping

**Tsygnanenko 96 Model**
**w/ diamagnetic cusp and tilt**

## Particle Mapping – Spectral Matching and UBK Analysis

- Linkages can be determined by virtue of Energetic particles guided by magnetic field lines between two locations -  Mappings of detailed spectral shapes have been explored between lEO and GEO and between MEO and HEO – these techniques effectively test empirical magnetic field models
- At lower particle energies, UBK analysis is required to establish interspacecraft mappings owing to the importance of electric drifts– Comparisons of particle distributions between HEO spacecraft (I.e., Whipple et al.) can be used in conjunction with UBK to extract electric fields with a presumed magnetic configuration; this is a powerful tool that has only recently been fully exploited – more work is called for!

## MI Connections Through Associations of Distinct Features

- Specific gross features in the ionosphere and magnetosphere can be exploited to establish linkages -  Examples include:
- velocity-dispersed ions in the cusp associated with reconnection
- north-south aligned arcs in the aurora associated with Bursty bulk flows
- identification of the open-closed boundaries in the magnetosphere and ionosphere

## HEO/MEO Comparisons of the OCB Location

- From Fennell et al., 1999

***HEO/MEO Comparisons of the OCB Location***

## Particle Precipitation Region Identification

- Newell and Meng have provided the most modern Statistical roadmap of ionospheric precipitation to its magnetospheric source Using DMSp; the statistical picture provides rich insights into event analysis

## Global Numerical Simulation/Global Ionospheric Comparisons

- Global MHD models can provide 			            a time-dependent, global roadmap; 			         but how do we test such models?
- Synoptic Ionospheric observations 		         (ground magnetometer arrays 			        and radars) provide movies of 		          evolving convective flows that 			       are of the appropriate size scale for MHD – this is just one approach for validation
- Growing use of this data/model comparison holds the promise of truly global context, at least in some limited cases and in some limited senses

## Particle Mapping Between Two High-Altitude Spacecraft: 

***Particle Mapping Between Two High-Altitude Spacecraft: ***
***Polar/Geotail Comparisons***

## Particle Mapping Between Two High-Altitude Spacecraft: 

***Particle Mapping Between Two High-Altitude Spacecraft: ***
***Polar/Geotail Comparisons***

## Establishing a Magnetospheric-Ionospheric Roadmap

- A Richly historic topic that would be difficult to review comprehensively in this talk – I’ll discuss mostly recent ideas instead and use representative examples (so my apologies in advance)
- A critically important but elusive issue, elusive owing to the complexities of the mapping and the inherent time-dependencies that complicate associations
- A problem that grows more imperative as we seek understanding of the intimately coupled global ionosphere-magnetosphere as a system
- Progress is being made on many fronts and that is helping to define the next class of major missions