Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 13, 2012 at 07:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update June 2, 2012)] [Cycle 24 progress NEW]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 1, 2012)]

[POES auroral activity level since October 2009 - updated July 2, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to active on July 12. Solar wind speed at SOHO ranged between 346 and 471 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 165.4 (increasing 20.5 over the last solar rotation). The Potsdam WDC planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 15.6). Three hour interval K indices: 44432212 (planetary), 23442312 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight UTC the visible solar disk had 9 spotted active regions (in 2K resolution SDO images).

Region 11518 [N12W42] was quiet and could become spotless today.
Region 11519 [S16W32] was quiet and stable.
Region 11520 [S17W05] decayed slowly losing many small spots and some penumbral area. Opposite polarity umbrae within the huge penumbra are not as close as they were before the X1 flare. The complex magnetic layout has changed little over the last day and further X class flares are possible. Flares: C4.0/1F at 01:36, C3.1 at 08:05, major long duration X1.4 event peaking at 16:49 UTC. A wide and large CME was visible in STEREO imagery from 17:00 UTC. While there were no LASCO imagery at the time, later images displayed a full halo CME. The flare was associated with an above 10 MeV proton event.
Region 11521 [S22W23] decayed in the trailing spot section barely retaining rudimentary penumbra. The leader penumbra increased its area. Flare: M1.0/1F at 20:03 UTC
New region 11522 [N12W21] was first observed with spots on July 7 and was numbered by SWPC 5 days later when new flux emerged in the leading spot section.
New region 11523 [S28E31] emerged on July 11 and was numbered by SWPC the next day.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1776
[S16W14] was mostly quiet and stable. Flare: C1.3 at 01:09 UTC.
S1777 [S12W08] was quiet and stable.
S1785 [S23W40] decayed slowly and quietly.

Coronal mass ejections (CMEs)

July 10-11: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
July 12: The X1 LDE in AR11520 was associated with a large and very wide CME. The core of the CME is likely Earth directed and could reach Earth before noon on July 14.

Coronal holes

Coronal hole history (since October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

No obvious potentially geoeffective coronal holes are currently in or near Earth facing positions. 

Coronal hole map

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, 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 this method, the extent and intensity of both CHs 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 13 and early on July 14. The CME observed on July 12 could reach Earth near noon on July 14 and cause minor to very severe geomagnetic storming lasting 18-30 hours. Quiet to active is likely on July 16.

Coronal holes (1) Coronal mass ejection (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 magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11518 2012.07.03
2012.07.04
  2   N09W40 0000   AXX location: N12W42
11519 2012.07.04 1 2 1 S14W31 0050 HSX CSO area: 0070

location: S16W32

11520 2012.07.05
2012.07.06
53 44 18 S16W09 1460 FKC EKC beta-gamma-delta

location: S17W05

area: 1350

SWPC count, location, classification and area probably includes ARs S1776 and S1777

S1776 2012.07.05   25 11 S16W14 0200   DAO  
S1777 2012.07.05   6 2 S12W08 0040   HSX  
11521 2012.07.07
2012.07.09
18 19 13 S21W21 0210 ESI ESI beta-gamma

location: S22W23

area: 0320

11522 2012.07.07
2012.07.12
4 9 5 N13W21 0020 CRO CRO  
S1785 2012.07.07   1   S23W40 0000   AXX  
S1787 2012.07.08       S20W48           plage
S1788 2012.07.09       N02W49           plage
S1790 2012.07.10       N08E39           plage
S1791 2012.07.10       N12E15           plage
S1792 2012.07.10       N26W16         plage
11523 2012.07.11
2012.07.12
6 11 7 S27E31 0010 BXO CRI  
S1794 2012.07.11       S27W21         plage
Total spot count: 82 119 57  
Sunspot number: 132 209 127  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 105 155 93  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 79 73 70 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K

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
 
2011.04 112.6 54.4 41.8 (+4.9) 8.83
2011.05 95.8 41.6 47.6 (+5.8) 8.94
2011.06 95.8 37.0 53.2 (+5.6) 8.06
2011.07 94.2 43.9 57.2 (+4.0) 8.16
2011.08 101.7 50.6 59.0 (+1.8) 7.26
2011.09 133.8 78.0 59.5 (+0.5) 12.27
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 96.7 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 (65.0 projected, +1.6) 7.15
2012.02 106.5 33.1 (66.5 projected, +1.5) 8.81
2012.03 114.7 64.2 (67.2 projected, +0.7) 16.08
2012.04 113.0 55.2 (66.5 projected, -0.7) 10.10
2012.05 121.5 69.0 (64.8 projected, -1.7) 7.06
2012.06 119.6 64.5 (64.0 projected, -0.8) 10.08
2012.07 157.3 (1) 49.8 (2A) / 128.7 (2B) (65.0 projected, +1.0) (17.46)

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 quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.