Solar Terrestrial Activity Report

Last major update issued on October 1, 2010 at 04:00 UTC.

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

Recent activity

The geomagnetic field was very quiet on September 29. Solar wind speed ranged between 347 and 438 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 89.9 (up 12.7 over the last solar rotation). The planetary A index  was 1 (STAR Ap - based on the mean of three hour interval ap indices: 1.1). Three hour interval K indices: 00001001 (planetary), 00001111 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight UTC the visible solar disk had 4 spotted regions.

Region 11109 added some small spots near the main penumbra and lost a few trailing spots.
Region 11110 slowly and could soon become spotless.
Region 11111 added a few small spots.

Spotted regions not numbered by NOAA/SWPC:
[S819] This region emerged in the northeast quadrant on September 30. Location at midnight: N16E04.

Coronal mass ejections (CMEs)

September 28-30: 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

No significant coronal holes are currently in or near Earth facing positions. A couple of small coronal holes are near Earth facing positions on October 1 and could be numbered later today.

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 fair to good. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on October 1-3.

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 Current Previous
11109 2010.09.21 11 17 N21W39 0240 DHI DSI  
11110 2010.09.26 3 2 N19W60 0030 BXO AXX area: 0010
11110 2010.09.29 1 5 N24E42 0010 AXX BXO  
S818 2010.09.29     S15W35         spotless
S819 2010.09.30   1 N16E04 0000   AXX    
Total spot count: 15 25  
SSN: 45 65  

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
2009.06 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 6.2 (+1.4) 3.88 / 3.61
2009.10 72.6 4.8 7.1 (+0.9) 3.66 / 3.56
2009.11 73.6 4.1 7.6 (+0.5) 2.45 / 2.63
2009.12 76.7 10.8 8.3 (+0.7) 1.41 / 1.92
2010.01 81.1 13.2 9.3 (+1.0) 2.93 / 3.07
2010.02 84.7 18.8 10.6 (+1.3) 4.15 / 4.61
2010.03 83.4 15.4 (12.3 predicted, +1.7) 4.58 / 4.65
2010.04 75.9 7.9 (13.9 predicted, +1.6) 10.22 / 10.24
2010.05 73.8 8.8 (15.2 predicted, +1.3) 9.18 / 8.15
2010.06 72.5 13.5 (16.6 predicted, +1.4) 8.17 / 6.85
2010.07 79.8 16.1 (18.3 predicted, +1.7) 6.31 / 5.15
2010.08 79.2 19.6 (19.5 predicted, +1.2) 8.49 / 7.77
2010.09 81.1 (1) 35.3 (2B) (20.7 predicted, +1.2) (5.33)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) 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. 2B) Month average to date.
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 on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.