Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 12 Apr 2004

By SpaceRef Editor
April 12, 2004
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.

Updated 2004 Apr 12 2210 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 103 Issued at 2200Z on 12 Apr 2004

IA. Analysis of Solar Active Regions and Activity from 11/2100Z
to 12/2100Z: Solar activity was at low levels. Region 588 (S15W68)
produced multiple C-class flares today. The largest was a C2/Sf
event that occurred at 12/0225Z. This region remains a reverse
polarity beta magnetic configuration. Updated LASCO imagery
indicates two separate occurrences of CME activity yesterday. A
partial halo CME was observed in response to the C9/Sf event
(erupted at 11/0419Z) that indicates potential for a glancing blow
from the likeliness of a resulting shock passage. The second, a
full halo CME first seen in C2 at 11/1154Z, was determined to be
backsided. New Region 591 (S15E01) was numbered today.

IB. Solar Activity Forecast: Solar activity is expected to be at
very low to low levels.

IIA. Geophysical Activity Summary 11/2100Z to 12/2100Z:
The geomagnetic field was at quiet to active levels. A shock passage
was observed at the ACE spacecraft at approximately 12/1730Z and it
is believed to be in response to the partial halo CME that was
associated with the C2 flare that occurred on 09/2040Z. Once again,
the IMF Bz remained predominantly northward and the geomagnetic
response was weak. Solar wind speeds peaked at near 540 km/s
shortly after the shock passage and has decreased to approximately
440 km/s at the time of this writing. The greater than 10 MeV
proton event that began at 11/1135Z, peaked at 35 pfu at 11/1845Z,
and ended at 12/0405Z. The greater than 2 MeV electron flux at
geosynchronous orbit reached high levels today.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to range from quiet to active levels. Minor storm
conditions may occur on 13 April in response to a shock passage from
yesterdays C9 flare and the associated partial halo CME. 14 and 15
April should see a return to predominantly unsettled levels with the
potential for active conditions, mostly in high latitude nighttime

III. Event Probabilities 13 Apr-15 Apr

  • Class M 15/15/10
  • Class X 01/01/01
  • Proton 10/05/01
  • PCAF green

IV. Penticton 10.7 cm Flux

  • Observed 12 Apr 091
  • Predicted 13 Apr-15 Apr 095/100/105
  • 90 Day Mean 12 Apr 109

V. Geomagnetic A Indices

  • Observed Afr/Ap 11 Apr 006/008
  • Estimated Afr/Ap 12 Apr 012/012
  • Predicted Afr/Ap 13 Apr-15 Apr 015/020-012/015-010/012

VI. Geomagnetic Activity Probabilities 13 Apr-15 Apr

A. Middle Latitudes

  • Active 30/25/20
  • Minor storm 15/10/10
  • Major-severe storm 10/05/05

B. High Latitudes

  • Active 40/30/20
  • Minor storm 20/15/10
  • Major-severe storm 10/10/05

SpaceRef staff editor.