Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 23 May 2002

By SpaceRef Editor
May 23, 2002
Filed under , ,

:Product: Report of Solar-Geophysical Activity
:Issued: 2002 May 23 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 143 Issued at 2200Z on 23 May 2002
IA. Analysis of Solar Active Regions and Activity from 22/2100Z
to 23/2100Z: Solar activity was low. Region 9961 (S22E22) grew
slowly as it produced a few minor C-class flares. The delta
configuration is now apparent in the center of the group, as the
leading spot simplified. Region 9957 (N10W19) decayed slightly but
still retains a modest degree of magnetic complexity. Two new
regions, 9966 (N10E34) and 9967 (N13E46) emerged.
IB. Solar Activity Forecast: Solar activity is expected to be
moderate. Regions 9957 and 9961 are the most likely sites for
isolated M-class flares. There continues to be a slight chance for a
major flare event.
IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z:
The geomagnetic field varied from quiet to severe storm levels. The
first of two shocks detected today passed ACE around 1000 UTC, as
solar wind speeds increased from 400 to 600 km/s, causing a sudden
impulse of 87 nT to be registered at Boulder at 1051 UTC. At
approximately 1500 UTC, a second shock, boosting solar wind speeds
to near 1,000 km/s for a short period, was seen at ACE. This
perturbation caused a 26 nT sudden impulse at Boulder at 1545 UTC.
This activity is thought to be an effect of the multiple CMEs
observed to leave the sun yesterday. The greater than 10 MeV proton
event that began at 22/1755 UTC attained a tentative maximum of 820
pfu at 23/1055 UTC and continues in progress.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at active to minor storm levels for the next 24 hours
as the current disturbance wanes. No additional shocks or CMEs are
expected. The field should continue to calm to unsettled conditions
by the end of the interval. The greater than 10 MeV proton fluxes
should continue to slowly decline.
III. Event Probabilities 24 May-26 May
Class M 50/50/50
Class X 10/10/10
Proton 35/10/10
PCAF yellow
IV. Penticton 10.7 cm Flux
Observed 23 May 180
Predicted 24 May-26 May 175/170/170
90 Day Mean 23 May 184
V. Geomagnetic A Indices
Observed Afr/Ap 22 May 010/014
Estimated Afr/Ap 23 May 045/050
Predicted Afr/Ap 24 May-26 May 025/030-015/015-010/010
VI. Geomagnetic Activity Probabilities 24 May-26 May
A. Middle Latitudes
Active 45/40/30
Minor storm 25/20/15
Major-severe storm 25/10/05
B. High Latitudes
Active 15/25/30
Minor storm 25/30/20
Major-severe storm 40/20/15

SpaceRef staff editor.