The GEM 99 Summer Workshop was the kick off
event for the inner magnetosphere/
storms campaign. The purpose of the campaign is to compare and
contrast a
small number of well-observed magnetic cloud events with the aim
of isolating
and understanding some of the most pressing science issues involved
in the
interaction of magnetic clouds with the interplanetary medium,
and the response
of the terrestrial environment. The goal is to apply information
on the inner
magnetosphere and its couplings to the solar wind, ionosphere
and magnetotail
during magnetic storms to the specification of an inner magnetosphere
module or
modules for the GGCM.
SELECTED EVENTS:
* 15-18 May 1997
* 24 Sep - 01 Oct 1998
(also an ISTP event study, ISR World Days were 21-25
Sep)
* 18-31 October 1998
(ISR World Days were 19-21 Oct)
SUMMARY:
The Plasmasphere/Ring Current Working Group
(WG1) conducted 5 sessions during
the GEM meeting last summer either alone or joint with other working
groups and
campaigns to identify major science issues that might be pursued
through
comparative analysis of the three storm events listed above.
These sessions
were:
* Introduction and planning for the magnetic storms campaign
(joint
WG1 & WG2)
* Ion outflow and convection (joint session between WG1 and
the M-I
Coupling Campaign
* Global picture of the 3 storm events (joint WG1 & WG2)
* Ring current/plasmasphere observations & models for
the 3 events
(WG1)
* Inner magnetosphere / tail coupling issues (joint session
among WG1,
WG2 and the Tail/Substorm Campaign
Major sciences issues identified in these sessions
focus on the impacts of
high solar wind dynamic pressure on: (1) ion outflow, (2) storm/substorm
coupling, (3) global electric field configuration and shielding
effects,
(4) fate of plasmaspheric material, and (5) ring current sources
and losses.
A sampling of new results is given below.
The POLAR spacecraft was within the polar cap
when the dynamic pressure
increased dramatically in Sept 98 and provided unique observations
of the
impacts on the ion outflow. Ion outflows were also observed by
LANL
geosynchronous satellites during the October 98 event. The auroral
oval
responded to the enhanced dynamic pressure by immediately brightening
uniformly
over the dayside oval; the nightside oval followed within 1 minute
on Sept 98.
Similar behavior was seen during the October 98 event. POLAR
EFI observed
electric fields down to L~2.2 during the main phase of the Oct
98 storm. SAIDs
were seen during both the Sept 98 and Oct 98 events from Millstone
Hill radar.
Fast flows were seen by MPA at geosynchronous orbit during the
Oct 98 event
possibly associated with the SAID event at low altitudes. MPA
observations
show magnetosheath and cold plasmaspheric ions on the same flux
tube during
both May 97 and Sept 98 raising the possibility of obtaining information
on
the fate of the plasmaspheric material during high solar wind
dynamic pressure
events. High solar wind dynamic pressure was due to high densities
during the
Oct 98 event and high velocities during the Sept 98 event raising
the
possibility for examining the impacts of these two different conditions
on ring
current sources and losses. The POLAR spacecraft passed through
the ring
current peak during the main phase of the Oct 98 storm providing
excellent
observations of the build up. Interesting signatures of superdense
plasma
sheets, extreme magnetic field stretching, reverse field draping
at dusk, ion
outflows, and plasmaspheric drainage were seen at geosynchronous
orbit during
some or all of these 3 events.