Joint CEDAR-TIMED Storm Studies Tuesday 18 June 2002 Front Range Theatre 03:30-05:30 pm

WORKSHOP OBJECTIVE:
Coordinated investigation of the MLTI response to the 17-24 April 2002 magnetic storms and solar particle events with special focus on the 17-18 April TIMED-CEDAR magnetic storm campaign.

MAGNETIC STORM DRIVERS:
Solar active region 9906 produced a series of geoeffective events during 17-24 April 2002 -- 2 halo CMEs as it traversed the solar disk and, as it approached the sun's limb, an X-class flare and solar particle event accompanied by a CME (not aimed directly at Earth) as seen by SOHO and TRACE. All of the CME's lifted off the sun with high velocity, and thus ACE observed them arrive at Earth in a relatively short time driving shocked solar wind plasma accompanied by significant populations of soft (10's of keV to few MeV) solar particles.

INITIAL ASSESSMENT OF IMPACTS AT EARTH:
The first interplanetary CME triggered a magnetic storm (min provisional Dst ~-100 nT) on April 17 which did not fully recover before the second CME hit on April 19 producing a second magnetic storm (min provisional Dst ~-150 nT). Throughout the 7-day interval NOAA POES observed the polar cap bathed in different species and energy ranges of solar particles. Soft protons (and electrons in the first storm) entered the polar cap with each CME and hard solar protons expelled by the X-class flare filled the polar cap for more than 48 hours at a time when magnetic activity was low. On April 23, the magnetosphere was clipped by the third CME which produced only weak magnetic activity levels (min provisional Dst~-50nT). After this series of events, evidence from Polar and NOAA POES suggests that the proton and electron radiation belts were modified, providing a long-lived source of high-energy precipitating particles for the MLTI region. There were several interesting features in the auroral oval during this sequence of storms. The auroral emissions and particle precipitation observed by FAST had unusual fine-scale structure. During April 18 and possibly other intervals, sawtooth oscillations (not yet understood but thought to be associated with "global" substorm-related activity) were observed by LANL geosynchronous satellites. IMAGE and TIMED captured the intensification of broad regions of the auroral oval which appear to be associated with these sawtooth oscillations. The strong driving of auroral activity resulted in a double oval configuration clearly seen by IMAGE, FAST and TIMED. Bright proton auroras were observed throughout the storm sequence. Dramatic perturbations in NO, mesospheric ozone, atmospheric composition and heating were documented by TIMED.

DATA SETS:
During the first magnetic storm in the series on 17-18 April 2002 (Kp~6-7), coordinated observations were made jointly by the TIMED satellite and a globally-distributed set of ground based instruments, including Incoherent Scatter radars, SuperDarn HF radars, Medium Frequency and Meteor Wind radars, lidars, Fabry-Perot Interferometers, and optical imagers. Other satellites also made supporting observations. The measurements were coordinated by the CEDAR-TIMED storm project. A wide-variety of satellites (including ACE, IMAGE FUV, ENA and EUV instruments, FAST, DMSP, NOAA POES, SAMPEX, SNOE, LANL geosynchronous satellites, GOES, and POLAR) observed different aspects of this event and members of these satellite teams are either currently collaborating or are being sought to join us in an analysis of these events.

WORKSHOP GOALS:
The goals of the workshop are

1. to make a first assessment of the data collected by the various ground and space instruments, and
2. to develop the plans for the joint analysis of the data by the CEDAR community and for the study of this event through globalmodels.
   
   

Interested participants should bring their data and their ideas for analyzing or modeling the event to the workshop, and should contact both convenors prior to the meeting for allocation of time on the agenda.

FUTURE PLANS:
These events will form the basis for a special session proposal for the Fall 2002 AGU meeting joint with SH/SM/SA leading ultimately to a set of papers collected into a special section of one of the journals. In preparation for this special session, a workshop is being planned for sometime in August to facilitate interactions between the aeronomy, ionospheric, magnetospheric, heliospheric and solar research communities. In addition, there are plans to hold a 2-day workshop at Millstone Hill in the late October- early November 2002 time frame focused on aspects related to the ground-based 17-18 April 2002 magnetic storm campaign.