Solar Terrestrial Activity Report

Last update issued on June 19, 2003 at 03:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 3, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update June 17, 2003)]

Recent activity

The geomagnetic field was active to severe storm on June 18. Solar wind speed ranged between 417 and 665 km/sec. A moderately strong solar wind shock was observed at SOHO at 04:44 UTC. The interplanetary magnetic field was mostly moderately to strongly southwards for several hours after the shock and this caused major to severe geomagnetic storming lasting until noon. The source of this shock is likely the full halo CME observed on June 15/16. A high speed stream from coronal hole CH44 dominated the solar wind after 15h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 120.4. The planetary A index was 54 (STAR Ap - based on the mean of three hour interval ap indices: 53.9).
Three hour interval K indices: 56764444 (planetary), 45433333 (Boulder). [SEC have since June 11 been reporting faulty values for the Boulder K indices in their RSGA and SGAS products. They are using the data from the high latitude magnetometer at College, Alaska instead of the ones recorded at Boulder by USAF.  As of June 16 NOAA/SEC is claiming that the Boulder magnetometer is faulty. The K indices as reported by USAF are used in this report.]

The background x-ray flux is at the class B3 level.

An above 10 MeV proton flux enhancement began at 09h UTC and became a proton event after 20h UTC. This event is intensifying slowly and has reached 22 pfu early on June 19. The source of this event is highly likely an eruption a few days behind the northwest limb in old region 10375. A CME associated with this event was visible in LASCO images shortly after the proton enhancement began.

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was very low with no events reaching the C class level.

Region 10380 decayed slowly and rotated to the southwest limb.
Region 10385 decayed slowly and quietly.
Region 10386 developed slowly and quietly as more spots emerged between the largest penumbrae. The region still has a magnetic delta structure and could produce major flares. The region is currently a reversed polarity region. New region 10387 rotated into view at the northeast limb on June 17 and was numbered by SEC the next day. The region has become more complex and has a weak magnetic delta structure in the trailing penumbra. A delta could be developing at the eastern edge of the leading penumbra as well. Minor M class flares will become possible if development continues in this region.

Spotted regions not numbered by NOAA/SEC:
[S186] A new region emerged in the southern hemisphere near the central meridian on June 17. Location at midnight: S18W19.
[S189] A new region emerged in the southeast quadrant on June 18. Location at midnight: S01E22.

Coronal mass ejections (CMEs)

June 17: A fast full halo CME was observed in LASCO C3 images after the major M class flare in region 10386 late in the day. The CME could reach Earth during the latter half of June 19 and intensify the current geomagnetic disturbance.

June 18: A large CME was observed off of the west limb after 09h UTC and was likely associated with an eruption in region 10375 which rotated over the northwest limb a few days ago.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent and well defined trans equatorial coronal hole (CH44) was in a geoeffective position on June 16-17. A new coronal hole (CH45) in the southern hemisphere is developing and will be in a geoeffective position on June 18-19.

Processed SOHO EIT 284 image at 02:06 UTC on June 19. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on June 19-20 due to a high speed stream from coronal hole CH44 and CME effects. Unsettled to active is likely on June 21-23 as a high speed stream from coronal hole CH45 dominates the solar wind.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless and will likely be useless to very poor until at least June 24. Propagation along north-south paths is poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay (weak signal), other frequencies were more interesting with stations from Brazil noted on 1480, 1510 and 1590 kHz.]

Coronal holes (1)	Coronal mass ejections (2)	M and X class flares (3)

1) Effects from a coronal hole could reach Earth within the next 5 days.
2) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.

Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.

Active solar regions (Recent map)

Compare to the previous day's image.

Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SEC or where SEC has observed no spots.

Monthly solar cycle data

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically 30-50% less.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.