Status Report

Joint USAF/NOAA Report of Solar and Geophysical Activity 07 Sep 2005

By SpaceRef Editor
September 7, 2005
Filed under , ,
Joint USAF/NOAA Report of Solar and Geophysical Activity 07 Sep 2005

Prepared jointly by the U.S. Dept. of Commerce, NOAA,
Space Environment Center and the U.S. Air Force.
Updated 2005 Sep 07 2204 UTC

Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 250 Issued at 2200Z on 07 Sep 2005

IA. Analysis of Solar Active Regions and Activity from 06/2100Z
to 07/2100Z: Solar activity increased to high levels this period as
newly numbered Region 808 (S12E83) produced one of the largest solar
flares of Cycle 23. An X17/3b white light flare erupted in this
region at 07/1740Z. A large and fast CME was visible on the MK4
coronagraph at Mauna Loa. Intense centimetric radio bursts
accompanied this flare, including a 27,000 sfu Tenflare. Type II
(1860 km/s) and Type IV radio sweeps were also observed. This region
also produced a very long duration M1 flare, which peaked at
06/2202Z. A fast and bright CME (1400 km/s) on LASCO imagery was
observed with this event. The sunspot cluster associated with Region
808 is just now rotating into view, so an accurate assessment of
its true size and complexity will have to wait. Region 808 is the
return of old Region 798, which produced significant solar and
geophysical activity during its last passage on the visible disk.

IB. Solar Activity Forecast: Solar activity is expected to be
moderate to high. Region 808 is obviously a complex and
moderate-large size sunspot group with great flare potential. Expect
further major flares.

IIA. Geophysical Activity Summary 06/2100Z to 07/2100Z:
The geomagnetic field was quiet to active. Today’s powerful X17 flare
produced a sudden disturbance in the geomagnetic field at 07/1725Z.
This 82 nT magnetic crochet was one of the largest observed this
Solar Cycle. A slow rise in the greater than 10 MeV protons at
geosynchronous orbit began near issue time. The greater than 2 MeV
electron flux at geosynchronous orbit reached high levels again

IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to continue at quiet to unsettled levels with isolated
active periods. The CME activity associated with yesterday’s
long-duration M1 and today’s X17 flares were not Earth directed. The
greater than 10 MeV protons at geosynchronous orbit are slowly
rising now and are expected to continue to do so. These protons will
likely cross the 10 pfu threshold on 08 Sep.

III. Event Probabilities 08 Sep-10 Sep

  • Class M 70/75/75
  • Class X 30/30/30
  • Proton 60/50/40
  • PCAF yellow

IV. Penticton 10.7 cm Flux

  • Observed 07 Sep 100
  • Predicted 08 Sep-10 Sep 110/120/120
  • 90 Day Mean 07 Sep 091

V. Geomagnetic A Indices

  • Observed Afr/Ap 06 Sep 006/009
  • Estimated Afr/Ap 07 Sep 010/010
  • Predicted Afr/Ap 08 Sep-10 Sep 008/012-010/015-005/010

VI. Geomagnetic Activity Probabilities 08 Sep-10 Sep

A. Middle Latitudes

  • Active 20/20/15
  • Minor storm 05/05/05
  • Major-severe storm 01/01/01

B. High Latitudes

  • Active 25/25/20
  • Minor storm 10/10/05
  • Major-severe storm 01/01/01

SpaceRef staff editor.