Solar Terrestrial Activity Report

Last update issued on July 20, 2003 at 01:10 UTC. Flare info added at 05:45 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 active on July 19. Solar wind speed ranged between 473 and 755 km/sec under the increasing influence of a high speed stream from the easternmost geoeffective part of coronal hole CH48.

Solar flux measured at 20h UTC on 2.8 GHz was 146.0. The planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 27.1).
Three hour interval K indices: 43344445 (planetary), 53344345 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 11 spotted regions on the visible disk. Solar flare activity was low. A total of 16 C class events was recorded during the day. Optically uncorrelated flares: C1.3 at 18:26, C1.2 at 18:42, C1.3 at 19:09, C3.0 at 22:25 and C1.7 at 22:58 UTC. Most of these probably occurred in region 10410 but with neither SXI nor relevant SOHO image available during this time interval this can not be confirmed.

Region 10405 was quiet and stable.
Region 10409 decayed slowly and quietly.
Region 10410 developed impressively adding a significant amount of penumbral area. This large region has a strong magnetic delta structure in the central southern spot section and major flares are likely over the next few days. Flares: C1.4 at 03:21, C3.4 at 09:31, C1.1 at 11:23, C1.4 at 14:46, C1.4 at 15:25, C1.7 at 15:56 and C2.4 at 20:18 UTC
Region 10411 was quiet and stable.
Region 10412 developed slowly and remains capable of minor M class flare production. Flare: C1.8 (with an associated moderate type II radio sweep) at 01:36 UTC.
Region 10413 decayed slowly and could soon become spotless.
Region 10414 was generally unchanged and quiet.
New region 10415 (S210) emerged early on July 18 in the northeast quadrant and was numbered by SEC the next day. This region developed quickly on July 19 and currently has a magnetic delta structure in a leading penumbra. Flares: C1.1 at 14:22, C1.7 at 17:34 and C2.7 at 23:58 UTC.

Spotted regions not numbered by NOAA/SEC:
[S211] A new region emerged in the southeast quadrant early on July 18. Location at midnight: S06E04.
[S212] A new region emerged in the southwest quadrant on July 19. Location at midnight: S08W29.
[S213] A new region emerged in the southeast quadrant on July 19. Location at midnight: S20W25.

Coronal mass ejections (CMEs)

July 19: A faint partial halo CME was observed in LASCO C3 images early in the day following an event in region 10412. The CME was observed over the west limbs and some of the east limbs.

July 18: No potentially geoeffective CMEs observed.

July 17: A faint halo CME was associated with a C9 flare in region 10412. The CME was observed in LASCO C2 images after 09h UTC.

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 was in a geoeffective position on July 12-16. A coronal hole (CH49) in the southern hemisphere is rotating into view at the east limb.

Processed GOES SXI coronal structure image at 17:30 UTC on July 19. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to minor storm on July 20 and quiet to active on July 21-23.

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. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay.]

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.