Solar Terrestrial Activity Report

Last major update issued on July 5, 2010 at 04:10 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update July 2, 2010)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 3, 2010)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 4, 2010)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update July 3, 2010)]

Recent activity

The geomagnetic field was quiet on July 4. Solar wind speed ranged between 475 and 575 km/s under the decreasing influence of a high speed stream associated with an extension of the northern polar coronal hole.

Solar flux measured at 20h UTC on 2.8 GHz was 71.4. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.0). Three hour interval K indices: 21111122 (planetary), 21111222 (Boulder).

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

At midnight there were 2 spotted regions on the visible solar disk.

Region 11084 was quiet and stable.

Spotted regions not numbered by NOAA/SWPC:
[S785] This region emerged in the northwest quadrant early on July 4. Location at midnight: N17W39

Coronal mass ejections (CMEs)

July 2-4: No obviously Earth directed CMEs were seen in LASCO or STEREO images.

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 small trans equatorial coronal hole (CH412) could rotate into an Earth facing position on July 6.

Image courtesy of SDO (NASA) and the AIA consortium. Annotations are my own. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet on July 5-8. On July 9-10 there's a chance of unsettled conditions due to effects from CH412.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region Date numbered Spot count Location at midnight Area Classification SDO (NASA) / AIA 4500
image
Comment
SWPC STAR SWPC STAR
11084 2010.06.27 1 1 S19W32 0110 HSX HSX  
S785 2010.07.04   4 N17W39 0020   CRO  
Total spot count: 1 5  
SSN: 11 25  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
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)  
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.05 70.5 2.9 2.3 (+0.1) 4.75
2009.06 68.6 2.9 2.7 (+0.4) 5.22
2009.07 68.2 3.2 3.6 (+0.9) 5.49 / 4.55
2009.08 67.3 0.0 4.8 (+1.2) 5.70 / 4.89
2009.09 70.5 4.3 6.1 (+1.3) 3.88 / 3.61
2009.10 72.6 4.8 7.0 (+0.9) 3.66 / 3.56
2009.11 73.6 4.1 7.6 (+0.6) 2.45 / 2.63
2009.12 76.7 10.8 8.3 (+0.6) 1.41 / 1.92
2010.01 81.1 13.1 (9.2 predicted, +1.0) 2.93 / 3.07
2010.02 84.7 18.6 (10.4 predicted, +1.2) 4.15 / 4.61
2010.03 83.4 15.4 (12.1 predicted, +1.7) 4.58 / 4.65
2010.04 75.9 7.9 (13.6 predicted, +1.5) 10.22 / 10.24
2010.05 73.8 8.8 (15.0 predicted, +1.4) 9.18 / 8.15
2010.06 72.5 13.5 (16.4 predicted, +1.4) 8.17
2010.07 72.6 (1) 1.4 (2) (18.0 predicted, +1.6) (8.38)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official international sunspot number is typically 30-50% lower.
3) Running average based on the daily SWPC ap indices. Values in red are based on the official NGDC ap indices.

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.