Solar Terrestrial Activity Report

Last major update issued on June 6, 2006 at 04:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 1, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 1, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update April 1, 2006)]
[Historical solar and geomagnetic data charts 1954-2005 (last update March 3, 2006)]
[Archived reports (last update June 5, 2006)]

Recent activity

The geomagnetic field was inactive to quiet on June 5. Solar wind speed ranged between 323 and 359 km/s (all day average 345 km/s - down 51 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 77.9. The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0).
Three hour interval K indices: 11100211 (planetary), 11112311 (Boulder).

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

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

Region 10892 developed further and was quiet. C flares are possible.

Coronal mass ejections (CMEs)

June 3-5: No partly or fully Earth directed CMEs were observed in incomplete LASCO imagery.

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 (CH227) in the northern hemisphere was in an Earth facing position on June 4-6.

Processed SOHO/EIT 284 image at 19:06 UTC on May 26. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet early on June 6. A high speed stream from CH227 will likely arrive during the day and cause quiet to minor storm conditions until June 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) Effects from a CME are likely to be observed at 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 to fair. Propagation on long distance northeast-southwest paths is fair to good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay and Radio Vibración (Venezuela) were both audible during the night. On other frequencies stations from Brazil had the best propagation with several good signals around. 1510 WWZN was the only North American signal identified.

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.

Active region	Date numbered	SEC spot count	STAR spot count	Location at midnight	Area	Classification	Comment
10887	2006.05.26			S13W70			plage
10891	2006.05.30			S14W59			plage
10892	2006.06.04	13	12	S08E53	0230	EKI	area was 0350 at midnight
Total spot count:		13	12
SSN:		23	22

Monthly solar cycle data

Month	Average solar flux at Earth	International sunspot number	Smoothed sunspot number
2000.04	184.2	125.5	120.8 cycle 23 sunspot max.
2000.07	202.3	170.1	119.8
2001.12	235.1	132.2	114.6 (-0.9)
2005.04	86.0	24.2	31.6 (-1.9)
2005.05	99.3	42.7	28.9 (-2.7)
2005.06	93.7	39.3	28.8 (-0.1)
2005.07	96.4	40.1	29.1 (+0.3)
2005.08	90.5	36.4	27.4 (-1.7)
2005.09	91.1	21.9	25.8 (-1.6)
2005.10	77.0	8.5	25.5 (-0.3)
2005.11	86.3	18.0	24.9 (-0.6)
2005.12	90.7	41.2	(22.8 predicted, -2.1)
2006.01	83.4	15.4	(20.1 predicted, -2.7)
2006.02	76.5	4.7	(17.1 predicted, -3.0)
2006.03	75.4	10.8	(15.1 predicted, -2.0)
2006.04	89.0	30.2	(14.4 predicted, -0.7)
2006.05	80.9	22.2	(13.5 predicted, -0.9)
2006.06	76.4 (1)	1.7 (2)	(11.4 predicted, -2.1)

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% lower.

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.

[DX-Listeners' Club]