ISTP Magnetic Cloud Investigation:

May 20-29, 1996 cloud event

Note: This web page is preliminary, not citable, and for discussion purposes only

WIND detected a magnetic cloud which reached the Earth at roughly 14 UT on 27 May 1996, with a shock arriving earlier in the day. The event was followed by a high-density "corotating stream" similar to the cloud events of October 1995 and January 1997. The event resulted in a considerable amount of geomagnetic activity.

According to my notes, a filament which was at (N 15.2 E 10.05 P 25.26) at 15:11 UT on the 21st of May appears to have lifted off somewhere around 17:00 UT on the 21st. According to GOES data, there was a really minor X-ray event at that time, followed by a very quiet period for several days.

Probably the easiest two to compare are the Sac Peak h-alpha images from the 21st and the 22nd.

The lack of activity in LASCO, EIT, and GOES makes (currently) the apparent filament eruption of the 21st the best candidate on the sun for any sort of disturbance.

Here is a table of data sources and the "filament status" at the time:

EIT    apparent eruption in progress at 04:00 UT 22 May 1996 
Sac peak  filament there at  13:37 21 May 1996
Big Bear   gone at   14:04 22 May 1996
Big Bear   gone at   16:26 22 May 1996
Space Environment Lab there at  14:05 21 May 1996
Holloman   there at   16:51 21 May 1996
Mees    gone at   17:39 21 May 1996
Mees    gone at   17:09 21 May 1996
Kitt peak  gone at   19:39 21 May 1996
Kitt peak  there at   16:51 21 May 1996

From this data, I estimate that the filament erupted close to 17:00 UT on 21-May-1996.

WIND Key Parameters:

May 27, 1996
May 28, 1996

Celias Proton Monitor Data:

Carrington Rotation 1909: 5 May - 1 June 1996

The solar wind velocity was slightly less than 400 km/sec during the event, indicating that a disturbance would take about 4.5 days to reach Earth. Tracing back, a disturbance which first reached Earth at 12 UT on the 27th travelling 380 km/sec would have originated at around 21 UT on the 22nd. If the speed were 450 km/sec, the estimated date would be 15 UT on the 23rd.

GOES X-ray Flux:

May 20-23, 1996
May 23-26, 1996

May 20, 1996:

Sac Peak halph 19960520_2016

May 21, 1996:

Nobeyama radio 19960521_0000
Sac Peak halph 19960521_1337
SEL halph 19960521_1405
Holloman halph 19960521_1651
Holloman halph 19960521_1939
Kitt Peak 10830 Å 19960521_1754
Mees caiik 19960521_1709
Mees caiik 19960521_1739
Mees caiik 19960521_2231
Sac Peak caiik 19960521_1341

May 22, 1996:

Big Bear caiik 19960522_1839
Big Bear halph 19960522_1626
Holloman halph 19960522_1950
Kitt Peak 10830 Å 19960522_1911
Sac Peak caiik 19960522_1408
Sac Peak halph 19960522_1404

May 23, 1996:

Big Bear caiik 19960523_1738
Big Bear halph 19960523_1639
Holloman_halph 19960523_1929
Sac Peak caiik 19960523_1401
Sac Peak halph 19960523_1357
Mees caiik 19960523_1651
Mees caiik 19960523_1759
Mees caiik 19960523_2251
Nobeyama radio 19960523_0000
Nobeyama radio 19960523_2345

May 24, 1996:

Holloman halph 19960524_0060
Holloman halph 19960524_1920
Sac Peak caiik 19960524_1451
Sac Peak halph 19960524_1448
Sac Peak caiik 19960524_1651
Sac Peak caiik 19960524_1657
Mees caiik 19960524_2204
Nobeyama radio 19960524_0045
Nobeyama radio 19960524_2345

May 25, 1996:

Holloman halph 19960525_1257
Kitt Peak 10830 Å 19960525_1827
Nobeyama radio 19960525_0045
Nobeyama radio 19960525_2345

SOHO had a momentum management maneuver on the 24th, and so the LASCO data was sparse for the 21st and 22nd of May. The LASCO CME list reports a "faint loop with core" out of the southeast on the 22nd, but nothing else until the 24th. The Mauna Loa CME list is "temporarily off line" so I'll have to actually contact a human... As far as EIT goes, you don't get a much quieter sun.

EIT Images:

In case you were wondering how to get a prompt response out of Joe Gurman, try saying something like "nothing much was going on in EIT."

With minimal effort, you can see that the filament is more prominent (no pun intended) and perhaps the span of it is larger as well.

GGS-GEM discussion of magnetospheric activity associated with this event

Polar CCR (Ceppad, Camice, Rapid) Science Thrust: Magnetic clouds

ISTP January 6-11 1997 Sun-Earth Connections Event Page

EIT Magnetic Cloud Events Page

This page was created 30 January 1997.
This page was revised on 30 January 1997.
Barbara J. Thompson