Introduction

    There is little doubt that reconnection occurs at some point during substorms. However, a big controversy still exists on whether reconnection in the magnetotail precedes or succeeds substorm expansion onset. The Near-Earth Neutral Line (NENL) model (Hones, 1979) proposes that the expansion phase of a substorm coincides with the onset of reconnection between field lines of opposite hemispheres after a growth period where lobe magnetic flux is added as a consequence of reconnection on the dayside magnetopause facilitated by a southward IMF Bz. Other models, however, suggest that expansion does not require reconnection and that the process of earthward transport can be achieved via other mechanisms such as near-Earth cross-tail current disruption, or a nonlinear growth of macroscale instabilities.

    As part of its participation in the International Solar Terrestrial Physics Program (ISTP), SRI International has scheduled, since the winter of 1995-1996, 84 intervals of Sondrestrom Incoherent scatter radar operations in coordination with POLAR, GEOTAIL, WIND, Interball Tail, and other ISTP spacecraft. These runs were designed to identify the mechanisms that  govern reconnection and the rate of transport in the magnetotail.

    The table below shows the intervals where there was geomagnetic activity. Note that the table includes five intervals of dedicated storm radar measurements in support of the National Space Weather Program.
 

Methods of convection measurement using the
Sondrestrom Incoherent scatter radar

ELEVATION SCANS

COMBINATION OF ELEVATION AND COMPOSITE SCANS
 


Reconnection and Convection Database

DATE
TIME INTERVAL 
(UT)
Feb 07-08, 1996
18-03
May 19-20, 1996
20-04
Sep 09-10, 1996
18-08
Dec 09-10,1996
18-06
Dec 10-11, 1996
16-04
Dec 15-16, 1996
20-04
Jan 01-02, 1997
17-05
Jan 12-13, 1997
22-06
Feb 08-09, 1997
19-06
May 27-28, 1997
18-04
Sep 30-Oct 02, 1997 (CME radar run)
16-01
Nov 06-08, 1997 (CME radar run)
09-06
Nov 21-22, 1997
21-06
Dec 01-02, 1997
20-04
Jan 08-09, 1998
21-06
Jan 13-14, 1998
22-06
Jan 28-30, 1998 (CME radar run)
20-02
Feb 03-04, 1998
22-06
Feb 08-09, 1998
19-04
Feb 09-10, 1998
21-06
Feb 14-15, 1998
21-06
Feb 19-20, 1998
21-05
Feb 20-21, 1998
21-05
Mar 02-03, 1998
21-05
Mar 12-13, 1998
22-06
Apr 23-24, 1998
20-04
Apr 29-30, 1998
21-08
May 04-05, 1998 (CME radar run)
09-09
May 21, 1998
01-10
May 30-31, 1998
18-05
Jun 10-11, 1998
21-10
Jun 20-21, 1998
22-05
Jul 06-07, 1998
22-07
Jul 11-12, 1998
22-08
Jul 16-17, 1998
21-05
Aug 06-07, 1998
22-03
Aug 11-12, 1998 (CME radar run)
22-22
Sep 01-02, 1998
22-05