National Aeronautics and Space Administration

Living With A Star

Targeted Research and Technology

Solar wind geoeffectiveness as a function of IMF and dynamic pressure and its effect on high-latitude ionospheric energy deposition

ROSES ID: NNH05ZDA001N      Selection Year: 2006      

Program Element: Independent Investigation

Principal Investigator: Athanasios Boudouridis

Affiliation(s): University of California, Los Angeles

Project Member(s):
Anderson, Phillip Charles Collaborator University of Texas at Dallas
Lyons, Larry Co-I UCLA
Zesta, Eftyhia Co-I NASA Goddard Space Flight Center
Ridley, Aaron James Collaborator University of Michigan


The electric field and particle precipitation patterns at high

latitudes are two of the most significant considerations for

determining the ionospheric state during steady or variable solar

wind and Interplanetary Magnetic Field (IMF) conditions. It is

therefore of primary importance to fully understand what drives

the electric fields and particle precipitation at high latitudes.

It is well known that the IMF is the major contributor to

geomagnetic activity on Earth. Recent studies, however, have shown

that solar wind dynamic pressure variations cause global effects

when they encounter the terrestrial magnetosphere, strongly

affecting the magnetosphere, ionosphere, and upper atmosphere. In

particular, it has been shown that solar wind dynamic pressure

enhancements significantly increase particle precipitation and

cause global intensification of the aurora, thus significantly

increasing the deposition of energy in the Earth's upper

atmosphere. In addition, the extent of the enhanced energy

deposition is dependent on the preexisting state of the

magnetosphere, which is controlled by the IMF orientation.

Further studies have demonstrated that solar wind pressure

increases also affect the cross-polar-cap potential drop (CPCP),

and thus the coupling efficiency between the solar wind and the

Earth's magnetosphere in ways that cannot be accounted for solely

by the existing solar wind electric field. It is rather the

combined contribution of IMF and dynamic pressure, in ways that

are yet to be determined, that controls the coupling efficiency

between the solar wind and the magnetosphere. Therefore, the

pressure enhancements and IMF variations affect both the solar

wind geoeffectiveness and the energy input

in the high-latitude ionosphere and upper atmosphere. We propose

to study the relative contribution of solar wind dynamic pressure,

IMF Bz, and IMF By to solar wind geoeffectiveness during

steady and variable conditions, and investigate under which

circumstances the correlation between solar wind geoeffectiveness

and high-latitude energy deposition is the highest. For this

purpose we will utilize a combination of solar wind measurements,

low-altitude Defense Meteorological Satellite Program (DMSP)

data, and results of the Assimilative Mapping of Ionospheric

Electrodynamics (AMIE) technique.

We will focus our research on the following scientific questions:

1) What is the effect of different IMF orientations and solar wind

dynamic pressure levels on the solar wind-magnetosphere coupling

efficiency under steady conditions? 2) How do variations of dynamic

pressure and IMF modify the CPCP and the coupling efficiency?

3) How permanent or transient are these responses for step-like

changes in the solar wind, and what are the relevant timescales?

4) What is the relative contribution of dynamic pressure and IMF

orientation to the CPCP and solar wind geoeffectiveness under

steady or changing conditions? 5) How do IMF orientation, dynamic

pressure levels, and their changes affect high-latitude energy

deposition as measured by the intensity of precipitating flux or

ionospheric Joule heating?


Performance YearReferenceInvestigation TypeActions
1Boudouridis, A.; Lyons, L. R.; Zesta, E.; Ruohoniemi,...
not set
1Boudouridis, A.; Lyons, L. R.; Zesta, E.; Weygand, J...
not set


Performance YearReferenceActions
1Zesta, E.; Boudouridis, A.; Raeder, J.; Larson, D. J...
1Boudouridis, A.; Zesta, E.; Lyons, L. R.; Anderson, ...
1Boudouridis, A.; Zesta, E.; Lyons, L. R.; Ruohoniemi,...
1Zesta, E.; Boudouridis, A.; Raeder, J.; Larson, D. J...
1Boudouridis, A.; Lyons, L. R.; Zesta, E.; Young, M....
1Boudouridis, Athanasios; Lyons, Larry; Zesta, Eftyhia;...

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