NATIONAL
SCIENCE FOUNDATION
|
NATIONAL
SCIENCE FOUNDATION
|
|
|
|
|
|
Solar Influences |
|
The Solar Influences Program at NSF is the aggregate of three related but distinct activities: The Solar Influences program supports research on those elements of Earth's space environment that are most important to Global Change. Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) CEDAR
is a broadbased community initiated upper atmospheric research program within
NSF's Division of Atmospheric Sciences. The goal is to understand the behavior
of atmospheric regions from the middle atmosphere upward through the thermosphere
and ionosphere into the exosphere in terms of coupling, energetics, chemistry,
and dynamics on regional and global scales. These processes are related
to the sources of perturbations that propagate upward from the lower atmosphere
as well as to solar radiation and particle inputs from above. The activities
within this program combine observations, theory and modeling.
Description The CEDAR concept originated in the mideighties and was developed over several years through workshops, symposia, and committee deliberations by nearly 100 scientists involved in aeronomical studies. These activities led to a comprehensive report that provided a framework for developing upper atmospheric research in the United States through an evolutionary strategy of instrument development and deployment coordinated with campaign activities related to the globalscale, coupled, nearearth environment. The program has attracted a large number of graduate students and many international collaborators. Guidance is provided by a science steering committee appointed by the NSF Aeronomy and Upper Atmospheric Facilities program directors; scientific feedback to the community is provided by newsletters and an annual summer workshop.Three broad categories embrace the scientific goals of the CEDAR program: (1) dynamics and energetics of the upper atmosphere, with particular emphasis on the hard to observe region between 80 and 150 km; (2) coupling between the mesosphere, ionosphere, thermosphere, exosphere, and magnetosphere; and (3) horizontal coupling between adjacent geographic regions. CEDAR has provided the community with improved spectrometers, interferometers, and imagers; allowed upgrades of existing facilities; and supported the development of lidars and small radars. Several facilities have been established containing a broad array of state of the art tools to provide a solid infrastructure with which to attack outstanding aeronomy problems well into the future. A report has recently been prepared that summarizes the results from the first five years of CEDAR funding. Link to Interim Review, 1988-1992 Prepared by the CEDAR Science Steering Committee Link to CEDAR Phase III Report Geospace Environment Modeling (GEM) Motivation and Purpose The magnetosphere illustrates very effectively the interconnectedness of earth system components. The space plasma environment also affects various technological systems, from ground-based power grids and communication systems to spacecraft. All space plasmas, energetic particles, and electromagnetic coupling effects of the near-space environment are filtered through the magnetosphere. The purpose of GEM is to support basic research into the dynamical and structural properties of the magnetosphere. One of the objectives is the construction of a global geospace general circulation (GGCM) model with predictive capability. Such a quantitative magnetospheric model would be analogous to existing general circulation models for the lower atmosphere and would also be linked to ongoing developments of general circulation models of the upper atmosphere (stratosphere to the thermosphere) being supported by the Aeronomy program and the CEDAR research opportunity. Description The strategy for achieving GEM goals is to undertake a series of "campaigns," in both theory and observational modes, each focusing on particular aspects of the geospace environment. The first campaign, continuing through about FY 1996, focused on the magnetospheric cusp and boundary layer. The second campaign on the magnetotail and substorms began in FY 1994 and is anticipated to continue through FY 1999. The third campaign on the inner magnetosphere began in 1996 and is expected to continue through 2000. A new campaign on Magnetosphere-Ionosphere coupling is expected to begin in 1999. Along with these focused area of research are observational campaigns based on various events of opportunity in which NSF-supported ground-based observations play an important and unique role. Ground-based access to the geospace environment has improved substantially within the past decade and both GEM and CEDAR are reaping the rewards of these technological advances.Radiative Inputs of the Sun to Earth (SunRISE)Radiative Inputs of the Sun to Earth (SunRISE) is a program that supports basic research on the impact of the Sun's varying radiative output (total irradiance, ultraviolet (UV) and extreme ultraviolet (EUV)) upon the Earth and its atmosphere. Description The Sun is now recognized to have undergone significant and welldocumented variations on long timescales. The indications are that modifications of some aspects of the solar activity have been associated with terrestrial climate changes such as the 17th century "Little Ice Age" and the 1112th century "Medieval Optimum." Modern observations now show irradiance changes on the scale of a few years, as well as on shorter timescales. These naturally occurring fluctuations in the radiative input to the Earth's atmosphere are small but comparable to other effects which are recognized as important for climate processes on the Earth. An understanding of these effects and the underlying physical processes is thus essential for the interpretation and understanding of the severity of modern anthropologicallyinduced global climate changes. The SunRISE initiative grew out of a communitywide workshop on this subject held in Boulder, Colorado in 1987, and a working document subsequently produced by the steering committee (RISE: A Research Plan for the 1990s on Solar Irradiance Variations). The purpose of this program of studies is to examine the origin of the variations in the total irradiance and the spectral irradiance of the Sun, particularly the UV and EUV components. The goal is to increase our understanding of the Sun's radiative output to the Earth and to improve our capability of predicting its changes. Special emphasis will be given to the nature of solar variability and the resulting terrestrial response. Together with the efforts already underway, which include interpretation of existing data as well as the development of new instrumentation and new observations, it is intended to support a wide range of studies on this problem.
|
|
|
The
Geospace Environment Modeling program focuses on the near-earth portion
of geospace from the lower ionosphere to where the earth system interacts
with the solar wind. This space plasma environment, called the magnetosphere,
is a strongly coupled, electrodynamic system which links the earth's atmosphere
with the local astrophysical environment. Thus, magnetospheric physics
is a discipline which stands at the intersection of earth system science
and modern astronomy.