October 22nd, 1999
Ionospheric Convection Movies
POLAR Auroral Movies
Movies made from Polar images on Friday, 22 October 1999
of the auroral storm that occurred over the
Observations of Solar Wind Conditions
- SOHO/EIT movie, October 17-18, 1999 (51Kb)
- EIT Image, October 17, 2312 UT
- EIT Image, October 18, 0024 UT
- SOHO/LASCO Movie, October 18, 1999 (356Kb)
- SOHO/LASCO C3 Movie, October 18, 1999 420 Kb
- LASCO C2 Image, October 18, 0126 UT
- LASCO C2 Image, October 18, 0626 UT
- LASCO C3 Image, October 18, 0818 UT
October 22, 1999 Event Summary
A solar wind interplanetary compound stream hits the Earth's magnetosphere
in the morning of October 22, 1999, and a display of intense
aurora at midlatitude over continental USA was observed by the
POLAR cameras (VIS, and UVI), while observers across the mid-west
sections of North America reported
the unusual sighting of aurora as far south as Kansas.
These disturbances noticed in America and elsewhere produced
the strongest magnetic storm of the year.
Preliminary time line
LASCO and EIT observed a partial halo CME beginning late UT on 1999/10/17,
and continuing into 1999/10/18. The event was first visible in C2 at 00:06
UT on 1999/10/18, as a bright arcade over NE limb. Fainter extensions were
visible along the east limb and over the south pole. The event extended over
about 210 degrees, from PA 0 (N pole) to PA 210 (SW limb). Measurements at
PA 45 (NE limb) show a gradual acceleration of 17 m/s^2 throughout the
field of view, with a final measured speed of 450 km/s at 13 solar radii.
EIT observed a filament activation and eruption, with an accompanying wave
event, on the SE portion of the disk, beginning at 23:12 UT on 1999/10/17.
WAVES/WIND and Culgoora/Australia detected type II radio burst enhancements
in the 10 MHz frequency range from 2327 to 2336 on October 17.
At 0145 UT on October 21 an IP shock reaches Earth compressing the
magnetosphere but causing minor 'unsettled' conditions to the
geomagnetic environment because it was followed by more than 12 hours
of an almost uninterrumpted northward interplanetary field,
with well above average (~ 20 nT ejecta magnetic field) solar wind speed of
> 400 km/s, and a mean density of approximately 12 AMU/cm^3 (ACE/MAG and
SWEPAM, and WIND/MFI and SWE NRT observations).
Near 21 UT on October 21, the plasma conditions remain the
same but the interplanetary magnetic field turns sharply South and starts large
amplitude oscillations which last until almost the end of the day when
the velocity of the solar wind and the magnitude of the ejecta's magnetic
field sharply increase to above 500 km/s and well above 20 nT respectively.
The geomagnetic disturbances reached maximum near 0700 UT when the ejecta
magnetic field near Earth reached above 30 nT while almost completely
oriented southward and disturbed storm time index (Dst) reached - 231 nT.
Followed by abrupt rise on the solar wind speed up to above 700 km/s
announcing the arrival of a high speed stream which continued to affect the
Earth vicinity for several more days.
During the more disturbed conditions several ISTP spacecraft were ideally
located to study the solar wind-magnetospheric-ionospheric coupling, with
GEOTAIL for example able to record very unusual radio emissions down-stream
of the Earth, in the magnetotail region (private communication Dr. Roger
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