Status Report

NOAA SEC Report of Solar-Geophysical Activity 13 Apr 2001

By SpaceRef Editor
April 13, 2001
Filed under , ,
:Product: Report of Solar-Geophysical Activity
:Issued: 2001 Apr 13 2200 UT
# 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 103 Issued at 2200Z on 13 Apr 2001
IA.  Analysis of Solar Active Regions and Activity from  12/2100Z
to 13/2100Z:  Solar activity was very low. Region 9415 (S22W59)
declined in size and number of spots during the period. This region
still retains a beta-gamma-delta magnetic configuration and is still
capable of producing M and X-class events. Region 9418 (N26W46)
developed into a more magnetically complex beta-gamma configuration,
however it produced very little activity today.
IB.  Solar Activity Forecast:  Solar activity is expected to be low
to moderate. Region 9415 is still capable of producing another major
flare before it rotates over the western limb.
IIA.  Geophysical Activity Summary 12/2100Z to 13/2100Z:
The geomagnetic field was at quiet to severe storm levels. A coronal
mass ejection (CME), from an M2 flare on 11 April, impacted earth at
13/0735 UTC. A sudden impact of 19 nT was detected at the Boulder
USGS magnetometer. The resulting disturbance caused major and severe
geomagnetic storm conditions from 13/1900-2100 UTC, and minor to
major storm conditions from 13/1200-1500 UTC. Conditions subsided to
active levels for the remainder of the period. The greater than 10
MeV proton event ended at 13/1800 UTC. The polar cap absorption
event (PCA) ended during the period.
IIB.  Geophysical Activity Forecast:  The geomagnetic field is
expected to be unsettled to minor storming for the first two days of
the period. These conditions will be the result of another impact at
earth of a CME. This CME originated from an X2 event on 12 April.
The expected arrival time is mid to late 14 April and at onset could
cause major storm levels, with brief severe storm levels at high
latitudes possible. Conditions should subside to quiet to active
levels on the third day.
III.  Event Probabilities 14 Apr-16 Apr
Class M    80/70/60
Class X    25/15/10
Proton     25/15/10
PCAF       green
IV.  Penticton 10.7 cm Flux
Observed           13 Apr 137
Predicted   14 Apr-16 Apr  135/130/140
90 Day Mean        13 Apr 166
V.  Geomagnetic A Indices
Observed Afr/Ap 12 Apr  029/038
Estimated Afr/Ap 13 Apr  025/035
Predicted Afr/Ap 14 Apr-16 Apr  050/055-025/030-015/015
VI.  Geomagnetic Activity Probabilities 14 Apr-16 Apr
A.  Middle Latitudes
Active                25/35/25
Minor storm           40/15/10
Major-severe storm    30/10/06
B.  High Latitudes
Active                25/35/35
Minor storm           30/25/20
Major-severe storm    40/20/12

SpaceRef staff editor.