Solar Terrestrial Activity Report

Last major update issued on July 19, 2011 at 06:15 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 19, 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 18. Solar wind speed ranged between 348 and 535 km/s under the influence of a high speed stream from the northern part of CH466.

Solar flux measured at 20h UTC on 2.8 GHz was 102.0 (increasing 7.1 over the last solar rotation). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.5). Three hour interval K indices: 23222212 (planetary), 13321322 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight UTC the visible solar disk had 11 spotted regions.

Region 11250 was quiet and stable.
Region 11251 was quiet and stable.
Region 11252 was quiet and stable.
Region 11254 displayed no significant changes and was mostly quiet. Flare: C1.0 at 10:28 UTC
Region 11255 was quiet and stable.
Region 11256 decayed slowly and quietly.
Region 11257 added penumbral area to the leader spot and appears to be maturing. Occasional C flares are possible.
New region 11258 emerged in the northeast quadrant on July 15 and was numbered by SWPC 3 days later.
New region 11259 rotated into view at the northeast limb on July 17 and got an SWPC number the following day.

Spotted regions not numbered by NOAA/SWPC:
[S1123] emerged in the northeast quadrant on July 17. Location at midnight: N10E28
[S1124] emerged in the southwest quadrant on July 18. Location at midnight: S34W55

Coronal mass ejections (CMEs)

July 16-18: 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) was Earth facing on July 14-18.

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 to active on July 19-21 with a chance of minor storm intervals due to a high speed stream from CH466. Quiet conditions are likely on July 22-23.

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
11250 2011.07.10 2 1 S27W61 0050 CSO HSX  
11251 2011.07.10
2011.07.11
3 2 N16W21 0080 HSX HSX

area: 0120

11257 2011.07.10
2011.07.17
12 15 N20W69 0120 DSI DSO

area: 0260

location: N21W70

S1112 2011.07.11     N06W44           plage
11255 2011.07.12
2011.07.14
5 9 N18W06 0020 CRO BXO location: N18W03
11252 2011.07.12
2011.07.13
  1 N25E06 0000   AXX

 

S1115 2011.07.12     N16W56           plage
11254 2011.07.13
2011.07.14
15 25 S22E11 0060 CAI CAI

location: S23E12

11253 2011.07.13     N14W82           plage
11256 2011.07.14
2011.07.15
4 6 N09W06 0020 DRO BXO

 

11258 2011.07.15
2011.07.18
5 6 N11W37 0020 CRO BXO formerly region S1120
S1121 2011.07.16     N18E18           plage
11259 2011.07.17
2011.07.18
1 6 N24E69 0030 DAO CAO formerly region S1122

location: N24E71

area: 0060

S1123 2011.07.17   1 N10E28 0000   AXX  
S1124 2011.07.18   1 S34W55 0000   AXX    
Total spot count: 47 73  
Sunspot number: 127 183  (raw spot count + 10 * number of spotted regions)
Classification adjusted SN: 81 98  (Sum of raw spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 76 60  k * (sunspot number). k = 0.6 for SWPC. k = 0.33 for STAR SDO

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 90.3 (1) 38.1 (2A) / 65.7 (2B) (49.4 predicted, +4.1) (8.93)

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.