Joint USAF/NOAA Report of Solar and Geophysical Activity 27 Jul 2002
:Product: Report of Solar-Geophysical Activity
:Issued: 2002 Jul 27 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 208 Issued at 2200Z on 27 Jul 2002
IA. Analysis of Solar Active Regions and Activity from 26/2100Z
to 27/2100Z: Solar activity increased to high levels. Region 44
(S22E03) produced two major flares early in the period: an M8/2n at
26/2112 UTC and an M5 at 26/2217 UTC, both associated with moderate
to strong discrete radio bursts. The M8 flare was also associated
with a full-halo CME. Both major flares occurred along the magnetic
neutral line separating Regions 44 and 39 (S16E07). Some decay was
observed in the leader spots of Region 44, but it remained large and
magnetically complex with a magnetic delta configuration evident
within its intermediate spots. Region 39 produced isolated C-class
flares including a C9/Sf at 27/0212 UTC. It also remained large and
complex, but changed little during the period. Strong magnetic delta
configurations persisted within its leading and trailing spots.
Region 45 (N06W25) was in a growth phase and displayed minor
polarity mixing. New Region 51 (S17E65) was assigned.
IB. Solar Activity Forecast: Solar activity is expected to be at
moderate to high levels. Isolated M-class flares are expected from
Regions 39 and 44. There is also a fair chance for a major flare
from either of these regions.
IIA. Geophysical Activity Summary 26/2100Z to 27/2100Z:
Geomagnetic field activity was at unsettled to active levels during
most of the period. This activity may have been due to a weak
high-speed solar wind stream. The greater than 10 MeV proton event
that began at 22/0655 UTC ended at 27/0320 UTC. The maximum flux for
this event was 28 pfu at 23/1025 UTC.
IIB. Geophysical Activity Forecast: Geomagnetic field activity is
expected to be at unsettled levels at the start of the period.
Activity is expected to increase to active to major storm levels
beginning late on 28 July as today’s halo CME reaches Earth. This
disturbance is expected to subside to mostly unsettled levels by 30
July. There is a chance for a greater than 10 MeV proton event
during the period.
III. Event Probabilities 28 Jul-30 Jul
Class M 80/80/80
Class X 30/30/30
IV. Penticton 10.7 cm Flux
Observed 27 Jul 231
Predicted 28 Jul-30 Jul 230/225/220
90 Day Mean 27 Jul 164
V. Geomagnetic A Indices
Observed Afr/Ap 26 Jul 010/017
Estimated Afr/Ap 27 Jul 013/017
Predicted Afr/Ap 28 Jul-30 Jul 010/012-025/030-018/020
VI. Geomagnetic Activity Probabilities 28 Jul-30 Jul
A. Middle Latitudes
Minor storm 10/20/10
Major-severe storm 01/10/05
B. High Latitudes
Minor storm 15/25/15
Major-severe storm 01/15/10