*************************** ** THE GEM MESSENGER ** *************************** Volume 6, Number 42 July 18, 1996 --------------------------- 1996 SNOWMASS REPORT TAIL/SUBSTORM CAMPAIGN WG 1 --------------------------- From: "Larry Lyons" WG-1 is data oriented with a focus of defining an accurate spatial and temporal description of the substorm process in the magnetosphere and ionosphere. The timing of events in one region relative to another is critical to address the questions of cause and effect. It is our intent to assemble definitive data sets that can address key science issues and with which models of substorm processes can be tested and validated. A number of studies that have been completed or are underway were discussed, and plans were made for substorm studies from the WIND perigee passes of the near-Earth tail. A. The following refer to previous GEM intervals where the data analyses have been completed or are well developed. Further work is expected to be accomplished outside of the workshop environment in the currently established collaborations. Lead investigator are noted in parenthesis: 1. CRRES onsets (Hughes): A study has been completed by Sergeev giving field-aligned currents and field-aligned curvatures. Paper to be written. 2. Propagation of substorm injection region (Reeves): Propagation Earthward of synchronous orbit was found to occur at ~24 km/s. Timings relative to ground onset and relative GEOTAIL observations is to be investigated. 3. GEOTAIL flow studies for 11-14 Jan. 1994 GEM interval (Angelopolous: "hit jackpot"): Well defined tailward to Earthward flow transitions seen after15/16 onsets within time interval. Using data from other periods, it was found that the time delay of the flow transition relative to onset decreases with decreasing distance to the Earth. 4. Detailed study of 14 Jan. 1994, 0629 UT onset and 18-21 UT interval of GEOTAIL activity (Maynard): Emphasized x-line relationships to aurora. The near-Earth x-line may be activated multiple times on closed field lines before breaking through to the lobe. Both the near-Earth x-line and the distant x-line may be operative simultaneously. Plasmoids are 3-dimensional structures, and may be limited in the GSM Y direction. Paper nearing completion. 5. Electric field changes relative to onset using Goose bay and Sondrestrom observations during March 1993 GEM interval (Lyons). Electric field changes are being analyzed relative to 3-5 onsets. Study is to be pursued by Sanchez, Blanchard, Greenwald and Lyons. B. Ad-hoc GEM intervals and analyses which are currently being pursued. Investigators with potential collaborative data should contact the lead investigators in each case (in parentheses) 1. Classic isolated substorm at 0430 UT on 9 Feb. 1995 with comprehensive ISTP observations (Lui): Apparently triggered by the IMF. Paper to be written. 2. Model predictions for Lui event (Winglee): Predictions of B compared to IMP 8 and GEOTAIL observations on the nightside. 3. Nice isolated substorm of March 9, 1995, at 0248 UT with excellent ISTP data and a 1 hr and 20 min growth phase (Rodger). Indications of a small ring current and more than usual penetration. Current analyses have included MHD simulations. Analyses are continuing. 4. Two ISTP events with good radar coverage, Sondrestrom imager data, and GEOTAIL in center of tail at 25 Re (Sanchez): Magnetosphere-ionosphere coupling of onsets to be studied. Onsets at ~2245 UT on 7 Feb. 1995, ~01 UT on 8 Feb.1995, ~23 UT on 23 Feb. 1995, and ~0310 UT on 24 Feb. 1995) C. New GEM intervals centered around the WIND perigee passes. Starting last fall GEM has been soliciting ground based observations to support interesting satellite configurations that occur during the WIND perigee passes through the near magnetotail. The spring WIND perigee passes have added POLAR and POLAR imaging to the ISTP fleet as well as the usual geosynchronous satellites and DMSP. A number of these events were extensively discussed and it is apparent that coordinated data sets will be able to address a number of substorm related questions. The following list records significant events detected on WIND during these intervals. The original list provided by Jim Slavin detailed the WIND and GEOTAIL info. Additional comments have been added as appropriate. 1. September 16, 1995: WIND B-field dipolarizations at X = -13 Re during 2200 - 2400 UT substorm. GEOTAIL observing IMF. Good Sondrestrom measurements of expansion into the polar cap. 2. November 29, 1995: WIND B-field dipolarizations at X = -12 Re during 0030, 0630 and 0740 UT substorms. GEOTAIL at the dawn magnetopause/magnetosheath. Good Greenland data for first event. IMP-8 IMF 3. January 13, 1996: WIND B-field dipolarization at X = -11 to -12 Re during 0300 and 1530 UT substorms. GEOTAIL skimming the dayside magnetosphere. First event has multiple injections. Super Darn good for entire period. Greenland good. Effects seen at INTERBALL. Day-night comparisons on second substorm. 4. March 27, 1996: WIND and GEOTAIL B-field dipolarization at X = -15 Re and -18 Re respectively during 0940 UT substorm. INTERBALL in solar wind. POLAR imaging. 0925 pseudobreakup followed by big breakup at 0945. Also events at 2200 to 0300 on the 28th. 5. April 18, 1996: WIND and GEOTAIL B-field dipolarizations at X = -12 and -14 Re during substorms at 0500, 0730, and 1030 UT. Separation of 1 Re in X and Z and 10 Re in Y. INTERBALL and IMP in solar wind. Optical aurora equatorward of L = 4 in S Hem. 6. May 10, 1996: WIND B-field dipolarization at X = -12 Re during 0400 substorm. GEOTAIL in dayside magnetosphere. Apparently no solar wind data (IMP data gap). GOES dipolarization at 2300 local. 0400 injection at geosync. 0359 onset in POLAR images. INTERBALL 0400 magnetopause crossing. Good radar data. The following lead investigators for each numbered event were identified along with the topics on which they will concentrate. 1. Sanchez - MI coupling and ground based signatures 2. McPherron - associations of Pi2is and flows 3. Greenwald/Lyons - day-night relationships (also involving event 4) 4. Angelopoulos - localization of near tail effects 5. Slavin - substorm conjunctions 6. a. Greenwald/Baker - nightside electrodynamics at onset b. Reeves - oscillations and injection effects - small onsets In addition the following studies involving all events were identified. X. Lyons/Sibeck - onset study Y. Slavin/Singer - long term study of all B effects. PLEASE check your data for supporting information and contact lead investigator. If other investigations are apparent, coordinate with lead investigators. Remember the rules of the road: ____________________________ If you use someone's data, offer that person a chance to be part of the study, to have the option of participating as a co-author or to add any necessary and pertinent caveats. Keep the data suppliers and coordinators informed as to who is pursuing what topics and events. _____________________________ Nelson Maynard (nmaynard at mrcnh.com) Larry Lyons (Larry_Lyons at qmail2.aero.org) +-------------------------------------------------------------------------+ |To add name to the mailing list, send a message to: editor at igpp.ucla.edu | |For message to whole GEM mailing list, send to: gem at igpp.ucla.edu | | | |URL of GEM Home Page: http://igpp.ucla.edu/gem/Welcome.html | |Please update your e-mail address. | |CAUTION: Do not send messages to gem at igpp.ucla.edu unless you want | | your message to go to everyone in the GEM mailing list! | +-------------------------------------------------------------------------+