Solar Terrestrial Activity Report

Last major update issued on July 16, 2011 at 06:30 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 11, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2110 [May-June 2011] - 2111 [June-July 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on July 15. Solar wind speed ranged between 374 and 484 km/s under the influence of a high speed stream from CH465 during the first half of the day.

Solar flux measured at 20h UTC on 2.8 GHz was 93.8 (decreasing 5.4 over the last solar rotation). The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.9). Three hour interval K indices: 13111112 (planetary), 13111122 (Boulder).

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

At midnight UTC the visible solar disk had 10 spotted regions.

Region 11245 was quiet and stable.
Region 11250 decayed slowly and was quiet.
Region 11251 was quiet and stable.
Region 11252 decayed and was quiet.
Region 11254 added a few spots and was quiet.
Region 11255 was quiet and stable.
New region 11256 emerged in the northeast quadrant on July 14 and was numbered the following day by SWPC.

Spotted regions not numbered by NOAA/SWPC:
[S1108] reemerged with a single spot on July 15. Location at midnight: N22W33
[S1112] emerged in the northeast quadrant on July 11. Location at midnight: N07W05
[S1120] emerged in the northeast quadrant on July 15. Location at midnight: N12E03

Coronal mass ejections (CMEs)

July 13-15: 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 large trans equatorial coronal hole (CH466) will likely become Earth facing on July 14-17.

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.

Forecast

The geomagnetic field is expected to be quiet on July 16. A high speed stream from the northwestern part of CH466 could reach Earth on July 17 and cause quiet to active conditions while the southern part of CH466 likely will cause unsettled to minor storm conditions on July 19-20.

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
11247 2011.07.03
2011.07.08
    S18W82          

location: S19W86

plage

11245 2011.07.06
2011.07.07
1 1 N13W49 0000 AXX AXX

location: N14W48

11248 2011.07.06
2011.07.08
    N20W44           plage
11249 2011.07.07
2011.07.09
    S16W59          

location: S18W39

11250 2011.07.10 4 6 S27W21 0080 CSO CSO location: S28W22
11251 2011.07.10
2011.07.11
1 3 N17E17 0100 HSX HSX

location: N15E18

S1108 2011.07.10   1 N22W33 0000   AXX    
S1110 2011.07.10     S28W33           plage
S1112 2011.07.11   5 N07W05 0000   AXX  
11255 2011.07.12
2011.07.14
3 8 N18E33 0000 BXO BXO location: N18E36
11252 2011.07.12
2011.07.13
3 2 N25E45 0010 BXO AXX

location: N24E47

S1115 2011.07.12     N16W17           plage
11254 2011.07.13
2011.07.14
5 8 S22E49 0050 CAO CRO

location: S24E51

11253 2011.07.13     N14W40           plage
11256 2011.07.14
2011.07.15
3 5 N09E34 0020 DRO DRO formerly region S1119

location: N07E36

S1120 2011.07.15   1 N12E03 0000   AXX    
Total spot count: 20 40  
Sunspot number: 90 140  

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 88.4 (1) 28.4 (2A) / 58.6 (2B) (49.4 predicted, +4.1) (9.48)

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.