Solar Terrestrial Activity Report

Last major update issued on July 1, 2004 at 03:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 2, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 2, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 2, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28, 2004)]
[Archived reports (last update June 21, 2004)]

Recent activity

The geomagnetic field was quiet to unsettled on June 30. Solar wind speed ranged between 534 and 569 km/sec under the the slowly decreasing influence of a high speed stream from coronal hole CH103.

Solar flux measured at 20h UTC on 2.8 GHz was 81.8 (lowest solar flux at Earth since the end of the last solar minimum). The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 11.9).
Three hour interval K indices: 32333232 (planetary), 33433322 (Boulder).

The background x-ray flux is at the class A3-A4 level.

At midnight there were 2 spotted regions on the visible disk. The solar flare activity level was low. A single C class events was recorded during the day.

Region 10639 decayed slowly in the trailing spot section.
Region 10640 decayed slowly. Flare: C1.3 at 14:39 UTC.

Coronal mass ejections (CMEs)

June 28-30: A limited number of LASCO images available during this interval. No obviously earth directed CMEs have been detected.

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 (CH103) was in a geoeffective position on June 26-27.

Processed SOHO/EIT 284 image at 13:05 UTC on June 15. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 1-4.

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. When the high speed stream has arrived the color changes to green.
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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is very poor. Propagation along long distance north-south paths is fair. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant stations tonight: Radio Vibración (Venezuela) and Radio Cristal del Uruguay. A nice opening was noted towards the Ceará region of Brazil near local sunrise with the best signals on 600 (interesting and unidentified), 620 (Rádio Assuncăo) and 930 kHz (Rádio Metropolitana).

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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

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 analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.