Solar Terrestrial Activity Report

Last update issued on July 15, 2003 at 03:55 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 quiet to active on July 14. Solar wind speed ranged between 444 and 605 km/sec. Weak solar wind disturbances were observed beginning at ACE at 10:44 and 21:50 UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 127.2. The planetary A index was 15 (STAR Ap - based on the mean of three hour interval ap indices: 16.4).
Three hour interval K indices: 33423334 (planetary), 24423434 (Boulder).

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

At midnight there were 10 spotted regions on the visible disk. Solar flare activity was low. A total of 2 C class events was recorded during the day.

Region 10401 decayed fairly quickly and lost about half of its penumbral area.
Region 10405 was generally unchanged and quiet.
Region 10406 decayed and could become spotless today or tomorrow.
Region 10407 developed slowly and quietly.
Region 10408 developed slowly and was quiet.
Region 10409 developed quickly during the latter half of the day adding many spots and nearly doubling the penumbral area. A magnetic delta structure has formed in the central eastern part of this compact region. M class flares are likely and a major flare is possible. Flares: C8.7 at 01:20 and C1.0 at 02:40 UTC.
Region 10410 was quiet and stable.

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. SEC has this region as part of region 10409. Location at midnight: N17E49.
[S206] This small region rotated into view at the northeast limb early on July 14. Location at midnight: N18E74.
[S207] Another region rotated into view at the northeast limb around noon on July 14. Location at midnight: N14E80.

Coronal mass ejections (CMEs)

July 12: With some LASCO images recently having become available, a fairly large CME and slow (source not yet identified) is evident in C3 images.

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: 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 and developing coronal hole (CH48) in the northern hemisphere and with a large trans equatorial extension will rotate into a geoeffective position on July 12-15.

Processed GOES SXI coronal structure image at 22:32 UTC on July 14. 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 15-18, 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 good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none, many stations noted, particularly from Brazil, Argentina and Uruguay. At times very good propagation towards Brazil above 1350 kHz with some of the low power stations still being received nearly an hour after local sunrise.]

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.