ISTP Magnetic Cloud Investigation:

SOHO MDI Magnetograms

The earliest detection of the halo event by LASCO was at approximately 16 UT on January 6. The SOHO MDI magnetograms show two regions of activity on the meridian during this time. An MDI GIF movie of January 6 - 7, 1997 (1.3 MB) shows the evolution of the two regions shown on disk in the next figure:

6-Jan-1997 09:19 UT MDI full-disk magnetogram

The magnetograms for a previous possible magnetic cloud event (observed August 6-9 1996 by WIND ) are shown in the following movie. The travel time between the sun and L1 for a typical CME during quiet sun is roughly 3 - 4 days (3 and 3/4 days for a CME going 450 km/sec). The event is shown on the sun for the days previous to the detected cloud event: MDI GIF movie (1.9 MB) of July 30 - August 6, 1996 combined with an EIT 171 Å movie of the same area.

The following is a series of magnetograms, roughly one per week, obtained by the SOHO Summary Database. These are available for comparison with the list WIND has compiled of possible magnetic cloud events:

    Calendar Day

148.7-150.5 (1996) May 27-29
183.5-185.0 July 1-3
220.5-222.5 August 7-9
357 December 24
10.0 (1997) January 10, 1997

mdi_19960731_1429 mdi_19960802_0359 mdi_19960809_2323 mdi_19960816_0907
mdi_19960823_1429 mdi_19960830_0629 mdi_19960906_0629 mdi_19960913_2048
mdi_19960921_0136 mdi_19960927_1741 mdi_19961004_1736 mdi_19961011_0805
mdi_19961018_0448 mdi_19961025_0941 mdi_19961101_0453 mdi_19961108_0141
mdi_19961115_0141 mdi_19961121_1749 mdi_19961123_0624 mdi_19961130_0941
mdi_19961207_0317 mdi_19961214_0805 mdi_19961221_0317 mdi_19961228_0805

A brief investigation of a previous cloud event is described on another page.

Return to the ISTP Sun-Earth Connections Event page

Return to the ISTP Event solar data page

This page was created 6 January 1997.
This page was revised on 19 January 1997.
Barbara J. Thompson