Storm-time sub-auroral electric fields: Ionospheric and magnetospheric control
ROSES ID: NNH05ZDA001N Selection Year: 2006
Program Element: Focused Science Topic
Principal Investigator: Pontus Brandt
Affiliation(s): The Johns Hopkins University Applied Physics Laboratory
Project Member(s):
Zheng, Yihua Co-I NASA Goddard Space Flight Center
Sotirelis, Thomas Co-I JHU/APL
DeMajistre, Robert Co-I The Johns Hopkins University Applied Physics Laboratory
Summary:
The role of electric fields in the sub-auroral ionosphere have been
underestimated for a long time largely due to the lack of
understanding of their origin and global behavior. Solar irradiation,
Joule heating and the ring current cause ionospheric electric
fields. Separation of their different origins is inherently difficult
due to limited spatial coverage of measurements (radars, low-latitude
satellites).
We propose to provide a realistic model of the sub-auroral electric
field, produced by the ionospheric closure of the ring current, using
observations and modeling, and investigate how it is controlled by
magnetospheric activity and ionospheric conductance. The output
electric fields is intended to be used as input by other thermospheric
models investigating the transport and density of the
ionosphere/thermosphere. Our work can be divided into the following
tasks.
TASK I - Perform a correlative statistical study of ionospheric
electric fields. Three types of electric fields will be investigated:
(1) Penetration (or undershielding) electric fields; (2) Sub-auroral
Polarization Streams (SAPS); (3) Midnight-dawnside, sub-auroral flow
reversals. Observational parameters will include solar wind
conditions, ionospheric conductance, Region-2 current intensity.
TAKS II - The sub-auroral, ionospheric electric field of selected
storm events will be modeled using the Comprehensive Ring Current
Model (CRCM), which computes the electric field, self-consistently
arising from the closure of the ring current through the ionosphere.
TAKS III - The results from the observational and model study will be
combined into a climatological model of the behavior of the
sub-auroral, ionospheric electric fields.
The most outstanding ionospheric effect is the uplift of plasma
through penetration electric fields on the low-latitude dayside,
causing storm enhanced densities (SED) in the F-layer. The SEDs
corotate into the duskside ionosphere where ring-current driven
electric fields transport plasma to mid-latitudes and sunward. The
SEDs have far reaching consequenses for a number of technological
systems over our heavily populated continent. For example, the Wide
Area Augmentation System (WAAS) assists positioning of civil aircraft
by providing time delay of Global Positioning System (GPS) signals
from geosynchronous satellites. However, WAAS can only provide time
delays from about a two dozen of stations over the North American
continent, forcing aircraft to interpolate the time delay value
between stations. At disturbed times, the ionosphere display very high
densities in very confined regions which makes the position
determination by interpolation invalid.
The proposed work fulfills the NASA National Objective: ``Study the
Earth system from space and develop new space-based and related
capabilities for this purpose.'' and all of its sub-objectives. As
recommended by the LWS TR\&T Science Definition Team, the proposed
work relies on large-scale modeling work that addresses the coupling
between the two traditional domains of the storm-time magnetosphere
and ionosphere and offers to provide its output (large-scale,
sub-auroral electric fields driven by the magnetosphere) to be used
further by thermospheric models. We therefore believe that the
proposed work will be a useful strategic capability in understanding
the storm-effects on the global electrodynamics and the mid- and low
latitude ionosphere/thermosphere system.
Presentations:
Performance Year | Reference | Actions |
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1 | Zheng, Y.; Brandt, P. C.; Sotirelis, T. S.; Talaat,Â...
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1 | Brandt, P. C.; Zheng, Y.; Talaat, E.; Sotirelis, T.;...
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1 | Talaat, E. R.; Sotirelis, T. S.; Hairston, M. R.; B...
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