SolarNews October 1991

We are now in month 60 of solar cycle 22. Solar activity levels observed in August were similar to those experienced in July. August had a total of 35 Class M or greater flares. There were only four M5 or greater events. The average monthly sunspot number in August rose by 3% over July while the average daily 10.7-cm flux decreased by 1%. The slight increase in sunspot number did not affect the tentative solar cycle 22 maximum of July 1989 as based on this index.

Flare activity was elevated during the first week of the month as Region 6757 (N22, L=246) dominated. This region grew from a simple bipolar group of only 10 millionths of the solar hemisphere when first observed on 29 July, to a large magnetically complex area measuring 1050 millionths six days later. It produced numerous moderate level flares and two major events during this time. The major events consisted of an X1/2B flare at 02/0318UT and an M7/2B at 03/2241UT. Flare activity dropped significantly between 8-15 August with the 10.7-cm flux falling to the lowest levels since April. Moderate to major flare activity returned on 16 August when region 6786 (S10, L=012) produced an M6/1B flare at 0621UT. Region 6805 (N22, L=245) produced the final major flare of the month just after its east limb transit. An X2/2B flare erupted from this area at 25/0115UT.

Only one satellite level proton event was observed during the month. The event began at 26/1704UT as a result of the X2 flare on 25 August. The event reached a maximum of 240pfu at energies greater than 10MeV at 27/1830UT and ended at 28/2005UT.

August had no geomagnetically quiet days. The most disturbed days were 12 and 19 August. The GOES-7 spacecraft experienced a magnetopause crossing between 12/1500-1630UT. This disturbance lacked a well correlated solar source. The disturbance on 19 August also lacked a definitive source. However, eruptive filaments may have contributed. Since late March, there have been a near record number of days at major storm levels or above. This level of activity has not been observed since 1960.

Solar activity should continue at generally moderate levels for the next several months with pulses possible through the beginning of 1991. Statistically, the equinox periods are more geomagnetically active, so September-October should continue at disturbed levels.

--The Space Environment Services Center

Announcing a conference on all aspects of solar and stellar seismology, to be held 11-14 August, 1992, at the Foothills Lab of the National Center for Atmospheric Research, in Boulder, Colorado.

The principal organizer for this meeting is Tim Brown (HAO/NCAR). The scientific organizing committee consists of:

J. Christensen-Dalsgaard (University of Aarhus) J. Harvey (National Solar Observatory) H. Hudson (University of California San Diego) R. Gilliland (Space Telescope Science Institute) J. Toomre (University of Colorado) W. Weiss (University of Vienna)

While there will be some time devoted at this meeting to the status and prospects of the GONG program as such, the organizers intend that the main focus of the conference should be on recent scientific results in helio- and asteroseismology. There will be published proceedings, and participants are encouraged to contribute poster papers to appear in these proceedings. A list of invited speakers and topics will be announced at a later time.

Those interested in attending this conference are invited to contact:

At this Workshop, presentation of new ideas, reviews, and problems in the following topics will be made through formal papers, panel discussions, and Working Groups.

• Solar activity, forecasts and impacts on geospace and geophysical activities

• Ionospheric events: their predictability and impacts

• Geomagnetic activity: forecasts, correlations with solar phenomena, impacts

• Evaluation of forecasts

• User requirements for solar-terrestrial predictions

• Review of the present solar maximum

For further information, please contact:

     Dr. Richard Coles               Tel: 1-613-837-4241
     ARWC Ottawa, Geomagnetism
     Geophysics Division, GSC        FAX: 1-613-824-9803
     1 Observatory Crescent
     Ottawa, Canada  K1A 0Y3         Telex: 053 3117

--Vic Gaizauskas