:Product: Weekly Highlights and Forecasts
:Issued: 2002 Apr 09 2212 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Environment Center
# Product description and SEC contact on the Web
# http://www.sec.noaa.gov/weekly.html
#
#                Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
01 - 07 April 2002

Solar activity ranged from low to high levels. Activity was low
during most of the period, but increased to high levels on 04 April
by virtue of an impulsive M6 X-ray flare at 04/1532 UTC. The source
for this flare was beyond the southeast limb, possibly from old
Region 9866 (S09, L =191), which had a history of energetic flare
production (see PRF #1385 – 1386). This region rotated into view on
05 April and was (re) numbered as Region 9896 (S11, L = 194,
class/area Hsx/110 on 06 April). However, Region 9896 appeared to be
a simply structured H-type spot group and produced no flares during
the rest of the period. C-class flares occurred during the rest of
the period from a number of active regions including Regions 9885,
9887, 9893 and 9899. Region 9885 (N13, L = 320, class/area Eki/710
on 01 April) was moderate in size and complexity. It was in a
gradual growth phase until 05 April, then began to slowly decay.
Region 9887 (N02, L = 296, class/area Eki/720 on 04 April) was in a
growth phase until 06 April, which included the development of a
short-lived delta magnetic configuration on 02 April. This region
appeared to stabilize on 07 April as a large, moderately complex
spot group. Region 9893 (N18, L = 215, class/area Eki/370 on 06
April) began to develop on 07 April with increased spots and
magnetic complexity. Region 9899 (N18, L = 183, class/area Hsx/180
on 07 April) showed gradual spot growth late in the period.

Solar wind data were available from NASA Advanced Composition
Explorer (ACE) spacecraft for most of the summary period. A
recurrent high-speed stream was in progress as the period began,
then subsided early on 04 April. The source for this high-speed
stream was a recurrent coronal hole. Solar wind velocities were
elevated during 30 March – (early) 04 April. The highest velocities
occurred during 31 March – 01 April with “gusts” in the 750 to 830
km/sec range. Another (weak) high-speed stream, also due to a
coronal hole,  commenced on 07 April associated with a relatively
minor increase in velocities (peaks to 470 km/sec).

There were no proton events at geo-synchronous orbit.

Greater than 2 MeV electron fluxes were at moderate to high levels
during 04 – 05 April. Normal to moderate flux levels occurred during
the rest of the period.

The geomagnetic field was disturbed during 01 – 03 April with
unsettled to active periods due to recurrent coronal hole effects.
Quiet to unsettled conditions occurred during the rest of the
period.

Forecast of Solar and Geomagnetic Activity
10 April - 06 May 2002

Solar activity is expected to be low to moderate. Isolated, low-level
M-class flares are likely during the period. There will also be a
chance for an isolated major flare during the period.

There will be a slight chance for a proton event through 15 April. No
proton events are expected for the rest of the period.

Greater than 2 MeV fluxes may reach high levels around 30 April – 02
May. Normal to moderate flux levels are expected during the rest of
the period.

Active geomagnetic field conditions are possible during 25 – 27 April
due to recurrent coronal hole effects. Quiet to unsettled conditions
are expected during the remainder of the period.


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