Solar Terrestrial Activity Report

Last major update issued on July 5, 2004 at 04:20 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 July 1, 2004)]

Recent activity

The geomagnetic field was quiet on July 43. Solar wind speed ranged between 406 and 468 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 79.4 (the lowest solar flux since the end of the last solar minimum). The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.9).
Three hour interval K indices: 22222222 (planetary), 21221212 (Boulder).

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

At midnight there was 1 spotted region on the visible disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10639 decayed slowly and quietly. At the current rate of decay this region could become spotless late today or tomorrow

Coronal mass ejections (CMEs)

July 2-4: No obviously earth directed CMEs were 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

No obvious coronal holes are currently approaching geoeffective positions.

Processed SOHO/EIT 284 image at 01:06 UTC on July 5. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 5-9.

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 poor. Propagation along long distance north-south paths is good. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay and an unidentified station from the Buenos Aires area. Post sunrise propagation was particularly good towards Argentina, but with some stations from Uruguay as well. Argentina was noted with fair to good signals on a number of frequencies including 710, 790, 870, 950, 1190, 1420 and 1430 kHz. Uruguay was on 930, 970 and 1130 kHz. Again a second Brazilian was observed on 740 kHz together with the dominant Rádio Sociedade, this must have been a station from the southernmost parts of Brazil.

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.