Solar Terrestrial Activity Report

Last major update issued on June 29, 2007 at 03:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update June 3, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update May 18, 2007)]

Recent activity

The geomagnetic field was quiet to unsettled on June 28. Solar wind speed ranged between 344 and 363 km/s (average speed was 348 km/s, decreasing 13 km/s from the previous day). Solar wind density increased significantly after 19h UTC as the leading front of a disturbance related to CH275 reached Earth.

Solar flux measured at 20h UTC on 2.8 GHz was 74.9. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 11112123 (planetary), 11212223 (Boulder).

The background x-ray flux is at the class A1 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 10961 decayd slowly and was quiet.
New region 10962 emerged near the southeast limb. This region appears to be unstable, however, only a single spot without penumbra was observed at the end of the day.

Coronal mass ejections (CMEs)

June 26-28: No obvious fully or partially Earth directed CMEs were observed in 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 coronal hole (CH275) in the southern hemisphere was in an Earth facing position on June 25-27.

.

Processed SOHO/EIT 195 image at 00:00 UTC on June 29. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on June 29-30 due to effects from CH275 and quiet to unsettled on July 1.

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.

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
10961 2007.06.25 5 2 S11E36 0180 CSO classification was HSX at midnight, area 0120, location: S09E34
10962 2007.06.28 2 1 S12E67 0040 BXO classification was AXX at midnight, area 0000, location: S08E64
Total spot count: 7 3  
SSN: 27 23  

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)
2006.04 89.0 30.2 17.1 (-0.3)
2006.05 80.9 22.3 17.3 (+0.2)
2006.06 76.5 13.9 16.3 (-1.0)
2006.07 75.7 12.2 15.3 (-1.0)
2006.08 79.0 12.9 15.6 (+0.3)
2006.09 77.8 14.4 15.6 (+0.0)
2006.10 74.3 10.4 14.2 (-1.4)
2006.11 86.3 21.5 12.7 (-1.5)
2006.12 84.5 13.6 (12.1 predicted, -0.6)
2007.01 83.3 16.9 (11.7 predicted, -0.4)
2007.02 77.7 10.6 (11.1 predicted, -0.6)
2007.03 72.2 4.8 (10.7 predicted, -0.4)
2007.04 72.4 3.7 (10.9 predicted, +0.2)
2007.05 74.4 11.7 (11.0 predicted, +0.1)
2007.06 73.6 (1) 18.5 (2) (11.3 predicted, +0.3)

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.


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