Solar Terrestrial Activity Report

Last major update issued on July 17, 2011 at 05:55 UTC. Minor update posted at 08:40 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 on July 16. Solar wind speed ranged between 346 and 462 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 93.8 (decreasing 5.3 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: 11111222 (planetary), 12221211 (Boulder).

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

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

Region 11245 was quiet and stable.
Region 11250 was quiet and stable.
Region 11251 was quiet and stable.
Region 11252 decayed and could soon become spotless.
Region 11254 developed slowly and was quiet.
Region 11255 was quiet and stable.
Region 11256 decayed slowly and quietly.

Spotted regions not numbered by NOAA/SWPC:
[S1108] reemerged on July 15 and developed further on July 16. Location at midnight: N19W42
[S1112] emerged in the northeast quadrant on July 11. Location at midnight: N06W18
[S1120] emerged in the northeast quadrant on July 15. Location at midnight: N10W12
[S1121] emerged in the northeast quadrant on July 16. Location at midnight: N18E44

Minor update added at 07:40 UTC on July 17: Region S1108 is developing very quickly and could produce C flares (the classification is currently CAI). Additionally there is an active region at the northeast limb which could be capable of C class flaring.

Coronal mass ejections (CMEs)

July 14-16: 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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet during the first half of July 17, there's a chance a high speed stream from the northwestern part of CH466 could reach Earth later in the day and cause quiet to active conditions. 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
11245 2011.07.06
2011.07.07
2 2 N14W65 0010 BXO BXO

location: N15W68

probably a new region which emerged several degrees to the west of the original 11245

11248 2011.07.06
2011.07.08
    N20W58           plage
11249 2011.07.07
2011.07.09
    S16W73          

location: S18W39

11250 2011.07.10 1 2 S26W34 0080 HSX CAO location: S28W35
11251 2011.07.10
2011.07.11
2 5 N16E04 0070 HSX CSO

location: N15E06

S1108 2011.07.10   7 N19W42 0010   BXO  
S1110 2011.07.10     S28W46           plage
S1112 2011.07.11   6 N06W18 0000   AXX  
11255 2011.07.12
2011.07.14
  7 N18E19 0000   AXX location: N15E22
11252 2011.07.12
2011.07.13
1 1 N25E32 0000 AXX AXX

location: N23E32

S1115 2011.07.12     N16W30           plage
11254 2011.07.13
2011.07.14
7 18 S22E36 0050 DSO DRI

location: S24E38

11253 2011.07.13     N14W53           plage
11256 2011.07.14
2011.07.15
2 4 N08E21 0020 CRO CRO

location: N07E23

S1120 2011.07.15   1 N10W12 0000   AXX  
S1121 2011.07.16   1 N18E44 0000   AXX    
Total spot count: 15 54  
Sunspot number: 75 164  (raw spot count + 10 * number of spotted regions)
Classification adjusted SN: 33 70  (Sum of raw spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10)

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 88.7 (1) 30.8 (2A) / 59.6 (2B) (49.4 predicted, +4.1) (9.26)

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.