Joint USAF/NOAA Report of Solar and Geophysical Activity 22 Apr 2003
SDF Number 112 Issued at 2200Z on 22 Apr 2003
IA. Analysis of Solar Active Regions and Activity from 21/2100Z
to 22/2100Z: Solar activity was low. Region 338 (N18W20) continued
to develop in both size and magnetic complexity. It was responsible
for most of the C-class activity this period, including a C4/Sf
flare at 22/2011Z. There were some indications that a weak delta
configuration was developing in this region. A Type II (960 km/s)
radio sweep was detected at 22/0716Z, associated with a CME off the
NE limb. A CME was also detected earlier in the period, associated
with a B-class flare in Region 336 (N14E10). The largest region on
the disk – Region 337 (S14E29), exhibited some decay and
simplification over the past 24 hours. These CMEs do not appear to
be Earthward directed. Minor C-class activity was observed in
Regions 337 (S14E29), and 339 (N16W71). New Region 342 (N18W07) was
numbered today.
IB. Solar Activity Forecast: Solar activity is expected to be at
low levels. There is a chance for a low level M-class flare from
Region 337 or Region 338.
IIA. Geophysical Activity Summary 21/2100Z to 22/2100Z:
The geomagnetic field was unsettled to active. A high speed solar
wind stream that began early on 21 April continues. Solar wind
speeds exceeded 600 km/s early in the period, but gradually declined
to below 550 km/s by the end of the period. The greater than 2 MeV
electrons at geosynchronous orbit reached high levels again today.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be at unsettled to minor storm levels. The most
disturbed periods are expected late on day one through day two due
to the anticipated arrival of a CME associated with the M2/1n flare
on 21/1307Z. A return to predominantly unsettled conditions is
expected on day three with occasional active periods possible.
III. Event Probabilities 23 Apr-25 Apr
- Class M 25/25/25
- Class X 05/05/05
- Proton 05/05/05
- PCAF green
IV. Penticton 10.7 cm Flux
- Observed 22 Apr 132
- Predicted 23 Apr-25 Apr 140/145/145
- 90 Day Mean 22 Apr 126
V. Geomagnetic A Indices
- Observed Afr/Ap 21 Apr 012/021
- Estimated Afr/Ap 22 Apr 015/022
- Predicted Afr/Ap 23 Apr-25 Apr 020/030-020/025-015/015
VI. Geomagnetic Activity Probabilities 23 Apr-25 Apr
A. Middle Latitudes
- Active 40/40/30
- Minor storm 20/20/10
- Major-severe storm 05/05/01
B. High Latitudes
- Active 50/50/40
- Minor storm 30/30/15
- Major-severe storm 15/15/05
