Geospace System

Proposal for a GEM Focus Group on "Geospace System"

submitted to the GEM Steering Committee, October 23, 2009 by Bill Lotko, George Siscoe, Simon Shepherd and Bob Strangeway

We propose to initiate a GEM focus group (FG) to undertake a global, system-dynamics study of the coupled solar wind-magnetosphere-ionosphere-thermosphere system. We refer to the coupled system simply as the geospace system (GS).

Motivation

The proposal responds to two circumstances: first, 50 years of magnetospheric research have shown the geospace system to be interactively coupled in multiple ways from the solar wind to the thermosphere; and second, as GEM continues to move in its long-range program from the ‘divide-and-conquer’ stage to the more challenging synthesis stage, a focus group devoted to problems of the coupled system will leverage scientific progress in each of the GEM research areas and their evolving focus groups. The magnitude of the task to comprehend the global system in its coupled complexity is almost certainly too great for a single, scientist-centered research team and probably too great for the multiple teams of a single institution. Instead it would seem to require a sustained collaborative effort by experts of manifold specialties distributed among many institutions. It might even take the combined collaboration of the GEM community and a sizable portion of the CEDAR community.

An open planning session was held at the 2009 GEM Workshop in Snowmass to explore community interest in a focus group on the geospace system. It was decided that the proposed FG naturally resides within the broad purview of the GGCM Research Area. The planning session identified FG objectives, desirable attributes of GS projects, prospective GS topical studies, and organization of FG efforts. These ideas are incorporated in this proposal.

Objectives

The primary objectives of the FG are:

1. To investigate problems in which the coupled solar wind-magnetosphere-ionosphere-thermosphere behaves as an integral system and to reveal the relationships between key elements of the system and their modes of interaction;

2. To facilitate GGCM development through i) applications of global models to these problems, ii) evaluation of their successes and deficiencies in capturing observed system behavior, and iii) identification of missing physics and strategies for improving model fidelity; and

3. To advance empirical understanding by identifying and coordinating observations applicable to the coupled solar wind-magnetosphere-ionosphere-thermosphere system, and to propose and coordinate empirical tests and validations of global models using key observations.

Attributes of Geospace System Study Projects

To achieve these objectives, the FG will need to marshal community resources and exploit synergies with other GEM Focus Groups. Thus candidate studies of the geospace system should:

• involve relational issues between system elements and processes, especially, though not exclusively, elements and processes that are being investigated by other GEM FGs;
• be addressable with existing tools, methods, and data sets, but be open to new developments;
• have sufficiently broad and compelling interest to enlist a critical mass effort;
• entail both model applications and observations; and
• rally community efforts and organization around “challenge” themes and studies.

Projects utilizing new or timely “assets” in global modeling and/or observational capabilities (e.g., AMPERE, multifluid MHD, coupled SWMIT models) are especially desirable. Building on the work of the two GGCM FGs ending in 2010 would provide continuity, e.g., topical study (I) described below may enlighten the interplay between reconnection and global current regulation (FG2) and augment the scope of validation studies (FG1). A Geospace System Challenge preferably would be undertaken jointly with new or recharged versions of the existing but soon-to-expire GGCM FGs.

Prospective Topical Studies

It became apparent at the 2009 Snowmass planning session that approaching geospace problems from a system perspective will likely require some reorientation in community thinking in order to pose the right system questions. Two problem areas emerged as prime candidates for the initial thrust of the focus group: (I) regulation of reconnection and transpolar potentials, including stormtime saturation, and the global current-voltage relation, and (II) global resonance and quasi-periodic response of the coupled magnetosphere-ionosphere to solar wind driving, including sawtooth phenomena. The first of these problems, to first approximation, may be regarded as a slowly evolving or quasi-static property of the system, whereas the second is fundamentally dynamic. As is typical of system problems, (I) and (II) are not necessarily independent. Both involve relatively unexplored effects of mixed plasma circulation (ionospheric and solar wind origin) and its nonlinear interaction with the ionosphere-thermosphere, e.g., effects on particle precipitation, conductance and electrodynamics.

Problem (II) on global resonance overlaps one of the key problems of GEM FG13 on Modes of Solar Wind – Magnetosphere Energy Transfer. Although this overlap to some extent diminishes the impetus for this study project in the context of a geospace system FG, the mainly observational approach of focus group (13) might find considerable synergy with the envisioned modeling approach that would emerge from a GGCM sponsored FG on geospace system.

It was decided at the Snowmass workshop to convene a second planning session at the Fall AGU Gem Mini-Workshop to define and further refine the FG thrust, and in fact, the effort may be limited to just one topical study at that time. A GS FG devoted to problems of global scope, e.g. prospective topics (I) and (II) described above, could potentially offer a scientific scaffold for all GEM FGs, and it may serve to sharpen the questions addressed by them, thereby, promoting greater FG synergy.

Planning for a Geospace System Challenge

If selected, the GS FG will hold at least 2 breakout sessions at the 2010 GEM Workshop to refine the science questions of the primary project. If a consensus for a second project, or a secondary project, emerges at the 2009 AGU GEM Mini-Workshop, its science questions would also be refined at the 2010 Summer Workshop. Initial planning for a geospace system Challenge will be discussed at the 2010 Summer Workshop. Candidate events and comparison studies that address the science questions of the Challenge would be identified. Interim progress on assembling and coordinating relevant data sets and model results, together with interpretations of observational and model results, will be reviewed at the 2011 Summer Workshop, which would also provide an opportunity to draw on CEDAR community expertise at the anticipated joint meeting of CEDAR and GEM. Results from the challenge will be presented and discussed at 2012 Summer Workshop. Possible venues for publication of challenge results by participating scientists include a journal special issue or section.

Focus Group Co-chairs - Bill Lotko, George Siscoe, Simon Shepherd, Bob Strangeway

Focus Group Term - Nominally 3 years; proposal to extend to 5 years may be considered in Year 3

Summary: Initial Planning Session at Snowmass 2009

Notes from the breakout session (~25 participants)

Distinguishing Science of Geospace System Investigations

• Behavior manifested by coupled system

• Various elements of system act in concert

Key Questions

• How do elements interact?

• What are the right system questions?

Focus Group Objectives

• Guide Model Applications and Development

- Use models to explore geospace system problems

- What new physics is needed in models to improve fidelity in describing system behavior?

• Advance Empirical Understanding

– Identify and coordinate observations applicable to system behavior

– Formulate empirical tests and validations

Criteria for Focus Group Projects

• Involve system problems, relational issues between system elements

• Addressable with existing tools and methods

• Sufficient interest, critical mass effort

• Entail model applications and observations

• Problems can be formulated as “Challenges”

Desirable: Opportunistic in utilizing timely “assets,” both modeling and observational capabilities

Next Steps

• Develop FG proposal (11/1)

• Establish open Wiki (8/1)

• GEM Messenger announcement (8/1)

• Advocates for FG projects to address criteria on Wiki

– Reconnection/transpolar saturation

– Global resonance and sawtooth oscillation

– ...

• Identify 2-4 most compelling projects (to be named in proposal)

• Select 2 at 2009 GEM Mini Workshop (if GS proposal is accepted)

• Pursue 2 projects beginning at 2010 GEM Workshop

Planning Session: Prospectus for a GEM Focus Group on the "Geospace System"

First planning session organized by Bill Lotko and George Siscoe at the 2009 GEM Workshop in Snowmass

We would like to initiate a discussion among the magnetospheric and aeronomy communities (portions, at least) on the prospect of undertaking a global, system-dynamics study of the coupled solar wind-magnetosphere-ionosphere-thermosphere system, which we identify simply as the geospace system. The suggestion responds to two circumstances: first, 50 years of magnetospheric research have shown the geospace system to be interactively coupled in multiple ways from the solar wind to the thermosphere, and second, as GEM moves in its long-range program from the 'divide-and-conquer' stage to the more challenging synthesis stage, a focus group devoted to problems of the coupled system will leverage scientific progress in each GEM research area. The magnitude of the task to comprehend the global system in its coupled complexity is almost certainly too great for a single, scientist-centered research team and probably too great for the multiple teams of a single institution. Instead it would seem to require a sustained collaborative effort by experts of manifold specialties distributed among many institutions. It might even take the combined collaboration of the GEM community and a sizable portion of the CEDAR community.

The priorities of such a focus group clearly must be enlightened by community interest. To begin the conversation we can suggest among many possible directions several problems, each global in scope and of considerable current interest . We have asked some GEM participants to help initiate the discussion with a few slides on each problem. They include: 1) the dayside reconnection potential, its relationship to the polar cap potential, and the saturation of both at large IMF; 2) global resonance, periodicity of the magnetospheric response, and sawtooth phenomena; 3) ionospheric-magnetospheric plasma circulation, including ionospheric outflows, and its effects on plasmasheet and inner magnetospheric dynamics; and 4) prompt penetration electric fields and their relationship to the dayside ionospheric superfountain, storm enhanced density, and plasmaspheric plumes. While some aspects of these global problems can be treated as regional phenomena, differentiated by distinct physical processes, their dynamics seem to evolve as an integrated whole during extreme solar wind conditions. The geospace system thus behaves coherently across a broad spatiotemporal range, making it difficult to unravel its causal behavior by considering the response in terms of isolated elements or processes. Integration of global problems of this type into a system-dynamics picture spans the expertise of all five GEM research areas and several CEDAR working groups. We invite participation from the GEM community in deciding whether the time is right for this focus group, and, if so, how best to structure its direction.