:Product: Weekly Highlights and Forecasts
:Issued: 2002 Sep 24 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
16 - 22 September 2002

Solar Activity ranged from low to moderate levels.  Moderate activity
was observed on 16 September and again on 20 September due to
impulsive M-class flare activity.  For flare times and magnitudes,
please refer to the Energetic Events or Optical Flare lists.  Low
activity was observed for the rest of the summary period.  The most
significant event during the period was a long-duration C8/1f flare
and associated CME on 17 September, from Region 114 (S12, L=288,
class/area Dkc/470 on 14 September).  The largest region on the
visible disk, Region 119 (S14, L=229, class/area Dkc/670 on 21
September), emerged rapidly over the course of the period, but did
not produce much beyond some scattered and predominantly impulsive
C-class flares.  Region 114 was the source of an impulsive M-class
flare on 16 September, and on 20 September, two impulsive M-class
flares occurred in Region 126 (S23, L=141, class/area Dao/180 on 20
September).  Some Type-II radio sweeps with associated CME’s visible
in SOHO/LASCO imagery occurred on 17 September and 19 September,
however the ejecta from these events did not appear earth-directed.

Solar wind data were available from the NASA Advanced Composition
Explorer (ACE) spacecraft for most of the summary period.  Solar
wind speeds followed a rising trend during 16-18 September and
persisted near 500 km/s for most of those days.  On 19 September, a
transient CME shock passage was observed just before 0600 UTC, and
subsequent wind speeds reached 750 km/s later that day.  Wind speeds
fell to near 400 km/s by early on 20 September, and remained near
that level for the rest of the period.  Total IMF field remained
mostly less than 10 nT throughout the period.  Some intervals of
persistent southward Bz near –5 nT were evident on 19 September and
22 September.

Energetic proton flux at geo-synchronous orbit remained near
background levels throughout the summary period.

The greater than 2 MeV electron flux at geo-synchronous orbit ranged
from normal to high levels during the period, in the wake of high
speed stream effects from the prior week.  Electron flux reached
high levels on 16-17 September and on 19 September.

The geomagnetic field was at quiet to active levels.  Elevated solar
wind speed caused isolated active periods 16-18 September.  The CME
shock arrival on 19 September, attributed to the long-duration C8
flare event discussed above, lead to sustained active conditions
late on that day.  Thereafter, quiet to unsettled levels persisted
for the remainder of the summary period.

Forecast of Solar and Geomagnetic Activity
25 September - 21 October 2002

Solar activity is expected to be low to moderate.  An increased
chance for moderate activity may accompany the expected return of
the Region 105/114 complex to the visible disk during 05-19 October.

The slight chances for a proton event occurrence will be somewhat
greater during the latter half of the period.

The greater than 2 MeV electron flux at geo-synchronous orbit may
reach event thresholds on 03-04 October and 09-10 October, due to
the possibility of recurrent coronal hole effects.

The geomagnetic field is expected to be mainly quiet to unsettled for
most of the forecast period.  Isolated active conditions are
possible on 02-03 October and on 08-09 October, in response to
recurrent coronal hole effects.


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