Copyright © National Academy of Sciences. All rights reserved.
Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR WIND-MAGNETOSPHERE INTERACTIONS
225
9.4.1 Regions
Observation from instruments on space platforms have provided researchers with a global view of the
different plasma regions found in the magnetosphere and enabled a general understanding of their statistical
structure and shape. During the past decade, space missions have delivered pathfinder global observations
of some of the inner magnetospheric regions. These observations, from the IMAGE and TWINS satellites,
were revolutionary in their global perspective but were unfortunately characterized by relatively low
spatial and temporal resolution. Also during the past decade, from THEMIS and from serendipitous alignments of Heliophysics Systems Observatory satellites, researchers acquired pathfinder one-dimensional
simultaneous in situ observations of the outer magnetosphere, but still have no unambiguous observations
of its two-dimensional or three-dimensional structure and evolution. In sum, scientists do not know the
instantaneous global and mesoscale structure of each of the various regions, nor how it evolves with time
and solar wind driving.
To understand how the system as a whole behaves in response to variations in the solar wind driver
requires a better view of the simultaneous evolution of the various parts of the system, leading to the first
SWMI science goal for the coming decade.
9.4.1.1 SWMI Science Goal 1. Determine How the Global and Mesoscale Structures in the Magnetosphere Respond to Variable Solar Wind Forcing
Digging Deeper
Investigation into the global and mesoscale magnetospheric reaction to the solar wind is a challenging
problem. Much like meteorology, the plasmas of geospace interact in a highly complex, nonlinear way.
Actions and reactions feed back on each other. For example, merging of the magnetic fields of the solar
wind and Earth may impose up to a few hundreds of thousands of volts across the entire magnetosphere,
activating an enormous, global convection cycle that strips away tons of near-Earth plasma and drags Earthward the plasma-loaded magnetic field lines of the distant nightside magnetosphere. In response, geospace
creates its own cross-scale network of intricately interconnected electrical currents and fields whose effect
is anything but uniform. Partial and temporary shielding occurs in some regions, while amplification of
solar wind driving occurs in other regions, although exactly where and on what timescales are poorly
known. Internal feedback profoundly modifies the whole system and can outlast by hours the cessation
of solar wind forcing.
Predicting the behavior of this highly coupled, self-modifying system will require powerful models
that include many physical processes operating over a wide range of spatial and temporal scales. The
development and validation of such models will require a strong foundation in observations of global
BOX 9.1 DECADAL SURVEY KEY SCIENCE GOALS
1. Determine the origins of the Sun’s activity and predict the variations in the space environment.
2. Understand the dynamics and coupling of Earth’s magnetosphere, ionosphere, and atmosphere and
their response to solar and terrestrial inputs.
3. Determine the interaction of the Sun with the solar system and the interstellar medium.
4. Discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe.
Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR WIND-MAGNETOSPHERE INTERACTIONS
225
9.4.1 Regions
Observation from instruments on space platforms have provided researchers with a global view of the
different plasma regions found in the magnetosphere and enabled a general understanding of their statistical
structure and shape. During the past decade, space missions have delivered pathfinder global observations
of some of the inner magnetospheric regions. These observations, from the IMAGE and TWINS satellites,
were revolutionary in their global perspective but were unfortunately characterized by relatively low
spatial and temporal resolution. Also during the past decade, from THEMIS and from serendipitous alignments of Heliophysics Systems Observatory satellites, researchers acquired pathfinder one-dimensional
simultaneous in situ observations of the outer magnetosphere, but still have no unambiguous observations
of its two-dimensional or three-dimensional structure and evolution. In sum, scientists do not know the
instantaneous global and mesoscale structure of each of the various regions, nor how it evolves with time
and solar wind driving.
To understand how the system as a whole behaves in response to variations in the solar wind driver
requires a better view of the simultaneous evolution of the various parts of the system, leading to the first
SWMI science goal for the coming decade.
9.4.1.1 SWMI Science Goal 1. Determine How the Global and Mesoscale Structures in the Magnetosphere Respond to Variable Solar Wind Forcing
Digging Deeper
Investigation into the global and mesoscale magnetospheric reaction to the solar wind is a challenging
problem. Much like meteorology, the plasmas of geospace interact in a highly complex, nonlinear way.
Actions and reactions feed back on each other. For example, merging of the magnetic fields of the solar
wind and Earth may impose up to a few hundreds of thousands of volts across the entire magnetosphere,
activating an enormous, global convection cycle that strips away tons of near-Earth plasma and drags Earthward the plasma-loaded magnetic field lines of the distant nightside magnetosphere. In response, geospace
creates its own cross-scale network of intricately interconnected electrical currents and fields whose effect
is anything but uniform. Partial and temporary shielding occurs in some regions, while amplification of
solar wind driving occurs in other regions, although exactly where and on what timescales are poorly
known. Internal feedback profoundly modifies the whole system and can outlast by hours the cessation
of solar wind forcing.
Predicting the behavior of this highly coupled, self-modifying system will require powerful models
that include many physical processes operating over a wide range of spatial and temporal scales. The
development and validation of such models will require a strong foundation in observations of global
BOX 9.1 DECADAL SURVEY KEY SCIENCE GOALS
1. Determine the origins of the Sun’s activity and predict the variations in the space environment.
2. Understand the dynamics and coupling of Earth’s magnetosphere, ionosphere, and atmosphere and
their response to solar and terrestrial inputs.
3. Determine the interaction of the Sun with the solar system and the interstellar medium.
4. Discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe.