Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 28 Jul 2005

By SpaceRef Editor
July 28, 2005
Filed under , ,

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Jul 28 2204 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 209 Issued at 2200Z on 28 Jul 2005

IA. Analysis of Solar Active Regions and Activity from 27/2100Z
to 28/2100Z: Solar activity was moderate due to an M1 x-ray event at
0030 UTC from newly numbered Region 792 (N12E78). The event was
associated with a CME off the east limb with a plane of sky speed of
about 850 km/s. Region 792 is clearly the return of old Region 786,
and is likely to have been the source of the recent series of CME’s
originating behind the east limb. The region was also responsible
for the remainder of today’s occasional C-class and B-class
activity. Region 791 (N14W20), the only other spotted group on the
Sun, was quiet and stable.

IB. Solar Activity Forecast: Solar activity is expected to moderate
with Region 792 as the dominant source of activity. There is also a
slight chance for major flare activity from this group.

IIA. Geophysical Activity Summary 27/2100Z to 28/2100Z:
The geomagnetic field was mostly unsettled to active with a minor
storm period from 0300-0600 UTC. Solar wind data indicate the onset
of a co-rotating interaction region late on the 27th followed by the
onset of coronal hole stream by about midday on the 28th. Solar wind
speed is currently steady at around 600 km/s. A greater than 10 MeV
proton event began at 2300 UTC on the 27th and reached a maximum so
far of 32 PFU at 1300 UTC on the 28th. The event continues in
progress with a flux of 27 PFU at the end of the analysis interval.
The main source for this event appears the shock driven by the fast
CME of 27/0454 UTC. It should be noted, however, the flux levels
were already enhanced prior to this event. This initial enhancement
may have been caused by one or more of the earlier CME’s that
originated behind the east limb; for example the CME’s of 26/0930
UTC, 25/1106 UTC, and 24/1418 UTC.

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be mostly unsettled with a chance for some active
periods for 29 July. Conditions are expected to decline to
predominantly unsettled for 30 July and should be quiet to unsettled
for 31 July. The greater than 10 MeV proton event is expected to end
sometime on 29 July, provided that no new particles are accelerated
by new activity from Region 792.

III. Event Probabilities 29 Jul-31 Jul

  • Class M 70/70/70
  • Class X 10/10/10
  • Proton 90/10/10
  • PCAF Yellow

IV. Penticton 10.7 cm Flux

  • Observed 28 Jul 096
  • Predicted 29 Jul-31 Jul 105/110/115
  • 90 Day Mean 28 Jul 096

V. Geomagnetic A Indices

  • Observed Afr/Ap 27 Jul 015/017
  • Estimated Afr/Ap 28 Jul 016/030
  • Predicted Afr/Ap 29 Jul-31 Jul 010/015-010/012-007/010

VI. Geomagnetic Activity Probabilities 29 Jul-31 Jul

A. Middle Latitudes

  • Active 35/30/25
  • Minor storm 20/20/15
  • Major-severe storm 05/05/05

B. High Latitudes

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

SpaceRef staff editor.