NOAA SEC Report of Solar-Geophysical Activity 10 Apr 2002

:Product: Report of Solar-Geophysical Activity

:Issued: 2002 Apr 10 2210 UTC

# Prepared jointly by the U.S. Dept. of Commerce, NOAA,

#Space Environment Center and the U.S. Air Force.

#

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 100 Issued at 2200Z on 10 Apr 2002

IA.  Analysis of Solar Active Regions and Activity from  09/2100Z

to 10/2100Z:  Solar activity was at high levels.  An M8.2/1N flare

occurred at 10/1231 UTC from Region 9893(N19W14) characterized by

parallel ribbons and multiple eruptive centers.  Associated with

this flare was a Type II radio burst (702 km/s) and a partial halo

CME observed from SOHO/LASCO imagery.  Region 9893 has begun to

decay and has simplified to a beta-gamma magnetic configuration.

Region 9899 (N18E22) has increased in magnetic complexity to a

beta-gamma spot and produced an M1.6/1n flare at 10/1907 UTC.

Region 9901(N20W02) has shown growth in spot count and magnetic

complexity.  Region 9904 (S16W21) has developed a small delta

configuration in the leader spot.  Region 9905 (S17E04) was numbered

today.

IB.  Solar Activity Forecast:  Solar activity is expected to be

moderate.  Region 9893 is in decay phase but still has the potential

for a major flare.  Region 9899 and Region 9901 are in a growth

phase and could produce M-class events.

IIA.  Geophysical Activity Summary 09/2100Z to 10/2100Z:

The geomagnetic field was at quiet levels for most of the day with

one period of unsettled conditions from 15-18Z.  The lingering

effects of the high speed stream appear to be ending.  Greater than

2 MeV electrons have returned to near background levels after three

days of enhancement.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is

expected to be quiet to active.  There is a chance of increased

geomagnetic activity late on day two due to a CME shock passage.  On

day three of the forecast period another CME shock is expected (from

the M8/1N flare on 10/1231 UTC) and geomagnetic activity is expected

to reach unsettled to active conditions.  There is a slight chance

of isolated minor storm levels especially at high latitudes.

III.  Event Probabilities 11 Apr-13 Apr

Class M    60/60/60

Class X    10/10/10

Proton     05/05/05

PCAF       yellow

IV.  Penticton 10.7 cm Flux

Observed           10 Apr 194

Predicted   11 Apr-13 Apr  195/190/185

90 Day Mean        10 Apr 203

V.  Geomagnetic A Indices

Observed Afr/Ap 09 Apr  002/006

Estimated Afr/Ap 10 Apr  006/008

Predicted Afr/Ap 11 Apr-13 Apr  004/008-008/010-012/015

VI.  Geomagnetic Activity Probabilities 11 Apr-13 Apr

A.  Middle Latitudes

Active                10/15/20

Minor storm           01/05/10

Major-severe storm    01/01/05

B.  High Latitudes

Active                15/15/20

Minor storm           05/05/10

Major-severe storm    01/01/05