Solar Terrestrial Activity Report

Last update issued on July 7, 2003 at 03:20 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 2, 2003)]

Recent activity

The geomagnetic field was quiet to unsettled on July 6. Solar wind speed ranged between 616 and 750 km/sec. A solar wind disturbance was observed at 12:25 UTC at ACE. Initially there was only a minor increase in solar wind speed and a more distinct increase in the total field of the interplanetary magnetic field. The source of the disturbance is uncertain but does not appear to be a coronal hole flow.

Solar flux measured at 20h UTC on 2.8 GHz was 129.6. The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.4).
Three hour interval K indices: 33233333 (planetary), 33133332 (Boulder).

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

At midnight there were 5 spotted regions on the visible disk. Solar flare activity was moderate. A total of 6 C and 1 M class events was recorded during the day.

Region 10397 developed slowly and was less active than what could be expected. There is a magnetic delta structure within a northern penumbra in the trailing spots. The region still has the potential to produce major flares. Flares: C4.4 at 04:40, C1.3 at 05:32, C1.2 at 18:08, C2.3 at 18:35 and C1.3 at 20:04 UTC.
Region 10398 was quiet and stable.
Region 10400 was mostly unchanged except for losing its magnetic delta structure after the M flare. Flares: M2.3 flare at 00:32 and C1.5 at 03:38 UTC.
New region 10401 rotated into view at the southeast limb early in the day.

Spotted regions not numbered by SEC:
[S198] A new region rotated into view at the southeast limb during the latter half of the day. Location at midnight: S08E75.
Another region is emerging south of region 10401.

Coronal mass ejections (CMEs)

July 4-6: Only a few LASCO images available from July 4 (with the last C2 image displaying a CME off of most of the east limb following an event in region 10400), no images from July 5-6 are available. There is a problem with the SOHO high gain antenna. Until the high gain antenna is in a favorable position starting from mid July, SOHO science data will be transmitted over a low gain antenna and only a limited amount of data will be available.

July 6: A CME appears to have been associated with the M2 event in region 10400 early in the day. A fairly large filament eruption was observed beginning at 03:00 UTC in region 10397 and stretching east northeastwards across the central meridian. The CME associated with this event could be geoeffective and reach Earth on July 8 or 9.

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 trans equatorial coronal hole (CH47) will be rotating into a geoeffective position on July 8-9.

Processed GOES SXI coronal structure image at 16:28 UTC on July 6. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on July 7. A CME associated with an M2 flare in region 10400 early on July 6 could reach Earth on July 8 and cause unsettled to minor storm conditions that day and on  July 9. A high speed stream from coronal hole CH47 will cause unsettled to active conditions on July 11-13.

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 poor to fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay (weak signal) at first, later on another station, probably from Venezuela, had the best signal.]

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.