Solar Terrestrial Activity Report

Last major update issued on July 3, 2006 at 02:25 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 7, 2006)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 7, 2006)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 7, 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 July 2. Solar wind speed ranged between 333 and 430 km/s (all day average 361 km/s - decreasing 82 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 87.1. The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.5).
Three hour interval K indices: 10001201 (planetary), 10011101 (Boulder).

The background x-ray flux is at the class A6 level.

At midnight there were 2 spotted regions on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10897 lost penumbra on the main spot, however, there a still several small spots in this region.
Region 10898 was mostly unchanged. C flares are possible.

Coronal mass ejections (CMEs)

June 30 - July 2: No partly or fully Earth directed CMEs were detected in incomplete LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent trans equatorial coronal hole (CH230) was in an Earth facing position on July 1-3.

Processed SOHO/EIT 284 image at 19:06 UTC on July 2. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be mostly quiet on July 3 and become unsettled to minor storm July 4-6 due to a high speed stream from CH230.

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. Propagation on long distance northeast-southwest paths is good. Trans Atlantic propagation conditions are normally monitored every night on 1470 kHz. Radio Cristal del Uruguay was the most frequently heard station, however, listening was very difficult because of an intense thunderstorm over the Bay of Biscaye. Only a few strong signals could be identified. Rádio Globo on 1220 kHz was very strong at S9+20dB while 1030 Radio del Plata and 1190 Radio América (both Argentina) were strong.

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
10897 2006.06.25 1 5 N06W23 0020 BXO  
10898 2006.06.28 13 12 S06E14 0290 CHO classification was DKO at midnight
S666 2006.06.28     N05W30     plage
Total spot count: 14 17  
SSN: 34 37  

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)
2005.05 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 23.0 (-1.9)
2006.01 83.4 15.4 (20.7 predicted, -2.3)
2006.02 76.5 4.7 (18.2 predicted, -2.5)
2006.03 75.4 10.8 (16.4 predicted, -1.8)
2006.04 89.0 30.2 (15.7 predicted, -0.7)
2006.05 80.9 22.2 (14.9 predicted, -0.8)
2006.06 76.5 13.9 (12.7 predicted, -2.2)
2006.07 86.3 (1) 2.3 (2) (11.3 predicted, -1.4)

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]