Solar Terrestrial Activity Report

Last major update issued on July 7, 2011 at 03:50 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, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 2, 2011)]

[POES auroral activity level charts since October 2009 - updated July 4, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on July 6. Solar wind speed ranged between 345 and 437 km/s under the decreasing influence of a stream from CH462.

Solar flux measured at 20h UTC on 2.8 GHz was 84.6 (decreasing 2.9 over the last solar rotation). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.1). Three hour interval K indices: 23311222 (planetary), 23421322 (Boulder).

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

At midnight UTC the visible solar disk had 7 spotted regions.

Region 11243 displayed only minor changes, the single penumbra took on an asymmetrical shape.
Region 11244 decayed slowly and quietly. The region will be rotating over the northwest limb today.

Spotted regions not numbered by NOAA/SWPC:
[S1096] rotated into view at the southeast limb on July 4. Location at midnight: S20E44
[S1100] emerged in the southeastern quadrant on July 5. Location at midnight: S35E04
[S1101] emerged in the southeastern quadrant on July 6. Location at midnight: S16E50
[S1102] emerged at the northeastern limb on July 6. Location at midnight: N14E74
[S1103] rotated into view at the northeastern limb on July 6. Location at midnight: N19E82

Coronal mass ejections (CMEs)

July 4-6: No obviously earth directed CMEs were observed.

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 coronal hole (CH463) in the northern hemisphere was Earth facing on July 5-6. A recurrent coronal hole (CH464)  in the southern hemisphere will become Earth facing on July 7-8.

The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using the new method, the extent and intensity of both holes are consistent with other data sources.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on July 7. A high speed stream from CH463 could reach Earth on July 8 and cause some unsettled and active intervals until July 10. On July 10-11 a high speed stream from CH464 could cause quiet to active conditions.

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

(Click on image for higher resolution image) Compare to the previous day's image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.

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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
11243 2011.06.27
2011.06.28
14 19 N15W46 0100 DAI CAO

location: N16W46

beta-gamma

11244 2011.06.27
2011.07.01
2 1 N14W79 0050 DSO HRX area: 0030
S1090 2011.06.29     N15W16           plage
S1092 2011.06.30     S20W55           plage
S1095 2011.07.02     N15W22           plage
S1096 2011.07.03   1 S20E44 0000   AXX  
S1097 2011.07.05     N01E23         plage
S1098 2011.07.05     N03E13         plage
S1099 2011.07.05     S23E14         plage
S1100 2011.07.05   1 S35E04 0000   AXX  
S1101 2011.07.06   2 S16E50 0000   AXX    
S1102 2011.07.06   3 N14E74 0010   BXO    
S1103 2011.07.06   1 N19E82 0000   AXX    
Total spot count: 16 28  
Sunspot number: 36 98  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2010.04 75.9 8.0 14.0 (+1.7) 10.22 / 10.24
2010.05 73.8 8.7 15.5 (+1.5) 9.18 / 8.15
2010.06 72.5 13.6 16.4 (+0.9) 8.17 / 6.85
2010.07 79.8 16.1 16.7 (+0.3) 6.31 / 5.15
2010.08 79.2 19.6 17.4 (+0.7) 8.49 / 7.77
2010.09 81.1 25.2 19.6 (+2.2) 5.33 / 5.45
2010.10 81.6 23.5 23.2 (+3.6) 6.07 / 6.27
2010.11 82.5 21.5 26.5 (+3.3) 4.80 / 5.50
2010.12 84.2 14.4 28.8 (+2.3) 3.41 / 4.35
2011.01 83.6 19.1 (30.6 predicted, +1.8) 4.32 / 5.51
2011.02 94.6 29.4 (32.6 predicted, +2.0) 5.41 / 6.44
2011.03 115.0 56.2 (35.2 predicted, +2.6) 7.79 / 8.18
2011.04 112.6 54.4 (38.1 predicted, +2.9) 9.71 / 8.83
2011.05 95.8 41.6 (41.4 predicted, +3.3) 9.18 / 8.94
2011.06 95.8 37.0 (45.2 predicted, +3.8) 8.96
2011.07 85.6 (1) 8.3 (2A) / 42.8 (2B) (49.4 predicted, +4.1) (10.13)

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 SIDC international sunspot number is typically 30-50% lower. 2B) Month average to date.
3) Running average based on the preliminary 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.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.