Solar Terrestrial Activity Report

Last update issued on July 16, 2003 at 02:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update July 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update July 2, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update July 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update July 11, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on July 15. Solar wind speed ranged between 548 and 612 km/sec. The solar wind disturbance which was observed beginning at ACE at 21:50 UTC on July 14 intensified early on June 15. Its most likely source is a filament eruption and an associated CME observed on July 11. A high speed stream from coronal hole CH48 arrived at approximately 19h UTC on June 15 at ACE.

Solar flux measured at 20h UTC on 2.8 GHz was 125.8. The planetary A index was 27 (STAR Ap - based on the mean of three hour interval ap indices: 27.9).
Three hour interval K indices: 55353344 (planetary), 55343344 (Boulder).

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

At midnight there were 11 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.

Region 10401 decayed quickly lost nearly all trailing spots.
Region 10405 was mostly unchanged and quiet.
Region 10406 decayed slowly and quietly.
Region 10407 decayed slowly and quietly.
Region 10408 was mostly unchanged and quiet.
Region 10409 decayed in the westernmost part of the trailing spot section while some development occurred in the easternmost part. There is a weak magnetic delta structure near the center of the region. Flares: C1.6 at 01:22, C2.0 at 02:07, C1.6 a5 02:21 and C1.6 at 03:04 UTC.
Region 10410 developed during the latter half of the day as polarities became mixed.
New region 10411 rotated into view on July 14 and was numbered by SEC the following day. Strangely SEC has chosen to include the spot of region S206 in this region. The spots both have positive polarity and the polarity fields surrounding the spots are well separated.

Spotted regions not numbered by SEC:
[S204] A new region emerged on July 13 to the west northwest of region 10409, slow development was observed on July 14-15. SEC has this region as part of region 10409. Location at midnight: N16E33.
[S206] This small region rotated into view at the northeast limb early on July 14. Location at midnight: N18E61.
[S208] A new region emerged in the  northwest quadrant west of region 10407 on July 15. Location at midnight: N11W29.

Coronal mass ejections (CMEs)

July 13: A filament eruption beginning at 00:32 UTC in spotless region 10404 and along the southern border of CH48 visibly affected the corona as far north as N20 (on the other side of coronal hole CH48) and areas well into the northwest quadrant. LASCO C3 images indicate a faint CME with most of the ejected material observed off the southern limbs.

July 14-15: No potentially geoeffective CMEs observed.

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 coronal hole (CH48) in the northern hemisphere and with a large trans equatorial extension will rotate into a geoeffective position on July 12-16.

Processed GOES SXI coronal structure image at 20:48 UTC on July 15. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on July 16-18, mainly due to a high speed stream from coronal hole CH48.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay, some stations from Brazil were noted as well. Listening was very difficult because of static caused by an intense thunderstorm moving into France.]

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.