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NOAA Space Weather Advisory

Official Space Weather Advisory issued by NOAA Space Environment Center
Boulder, Colorado, USA

2003 May 29 at 02:00 p.m. MDT (2003 May 29 2000 UTC)


Title: Major solar flares and Moderate to Strong geomagnetic storm

A recent series of three major flares have been observed on the Sun. All of
these flares have been from a complex sunspot region near the center of the
solar disk. The flare events all reached R3 level on the NOAA radio blackout
scale. The times of the flare events were 5:07 pm MDT on 27 May (27/2307
UTC), 6:27 pm MDT on 27 May (28/0027 UTC), and 6:47 pm MDT on 28 May
(29/0047 UTC). Strong solar wind has been observed in response to the first
two coronal mass ejections associated with the first two flare events, with
the first passage apparently around 5:55 am MDT on 29 May (29/1155 UTC) and
the second around 12:30 pm MDT on 29 May (29/1830 UTC). The strong solar
wind has increased geomagnetic activity to strong levels (G3 on the NOAA
scale). There is a good chance that there will be additional periods of
strong geomagnetic activity during the next 24 hours. In addition to the
current disturbances in progress, a coronal mass ejection associated with
the third solar flare is likely to pass the earth sometime between midnight
and 6:00 am MDT on 30 May 2003, which should also add to the current
geomagnetic disturbance. 

In addition, an S2 solar radiation storm is in progress in association with
the major flare activity.

G3 geomagnetic storms can lead to problems with electrical power systems
including the need for voltage corrections, and triggering of false alarms
on some protective devices. These storms also can affect spacecraft
operations including surface charging on satellite components, increases in
drag for low-Earth-orbit satellites, and corrections for orientation
problems. Additional effects include intermittent satellite navigation and
low-frequency radio navigation problems, intermittent HF radio, and aurora
as low as Illinois and Oregon (typically 50? geomagnetic lat.). 

R3 radio blackouts result in widespread HF radio communication outages on
the dayside of the Earth and can also degrade low frequency navigation

S2 solar radiation storms can lead to infrequent single-event upsets in
spacecraft operations, small effects on HF propagation through the polar
regions, possible small effects on navigation at polar cap locations.

Data used to provide space weather services are contributed by NOAA, USAF,
NASA, NSF, USGS, the International Space Environment Services and other
observatories, universities, and institutions. 

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