Solar Terrestrial Activity Report

Last major update issued on July 2, 2011 at 05:25 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 1, 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 active on July 1. Solar wind speed ranged between 308 and 512 km/s under the influence of a high speed stream from CH460.

Solar flux measured at 20h UTC on 2.8 GHz was 87.6 (decreasing 15.2 over the last solar rotation). The planetary A index was 13 (STAR Ap - based on the mean of three hour interval ap indices: 12.8). Three hour interval K indices: 34323321 (planetary), 23432322 (Boulder).

The background x-ray flux is at the class A9 level.

At midnight UTC the visible solar disk had 6 spotted regions.

Region 11242 decayed quickly retaining only rudimentary penumbra on the trailing spots.
Region 11243 developed slowly and was quiet.
New region 11244 emerged in the northeast quadrant on June 27 and was numbered 4 days later by NOAA/SWPC. Slow decay was observed on July 1, weak polarity intermixing is still present.

Spotted regions not numbered by NOAA/SWPC:
[S1088] reemerged with spots on June 30. Location at midnight: S25W19
[S1093] emerged in the southeast quadrant near the center of the visible disk on July 1. The region has reversed polarities. Location at midnight: S05E03
[S1094] emerged in the southwest quadrant on July 1. Location at midnight: S17W45

Coronal mass ejections (CMEs)

June 29 - July 1: 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 small coronal hole (CH461) in the northern hemisphere was in an Earth facing position on June 30 and closed the same day. A trans equatorial coronal hole (CH462) was Earth facing on July 1-2.

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 poor to fair.

Forecast

The geomagnetic field is expected to be quiet with occasional unsettled intervals on July 2-3. Quiet to active is likely on July 4-5 due to effects from CH462.

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
S1079 2011.06.23     N10W58           plage
11242 2011.06.26
2011.06.28
5 14 N18W45 0050 DRO CRO location: N16W43

area: 0030

11243 2011.06.27
2011.06.28
10 23 N17E22 0060 CRO CSO

location: N15E22

area: 0090

11244 2011.06.27
2011.07.01
6 13 N15W11 0010 BXO BXO beta-gamma

formerly region S1087

S1088 2011.06.27   1 S25W19 0000   AXX  
S1089 2011.06.28     S23W45           plage
S1090 2011.06.29     N15E49         plage
S1091 2011.06.29     S23W09           plage
S1092 2011.06.30     S23E06         plage
S1093 2011.07.01   2 S05E02 0000   BXO    
S1094 2011.07.01   1 S17W45 0000   AXX    
Total spot count: 21 54  
Sunspot number: 51 114  

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
2011.04 112.6 54.4 (38.1 predicted, +2.9) 9.71
2011.05 95.8 41.6 (41.4 predicted, +3.3) 9.18
2011.06 95.8 37.0 (45.2 predicted, +3.8) 8.96
2011.07 87.6 (1) 1.6 (2A) / 51.0 (2B) (49.4 predicted, +4.1) (12.75)

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.