Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 9, 2012 at 05:55 UTC. Most recent minor update posted at 20:30 UTC.

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

[POES auroral activity level since October 2009 - updated March 5, 2012]
Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to major storm on March 8. Solar wind speed at SOHO ranged between 456 and 828 km/s. A strong solar wind shock was observed at SOHO at 10:53 UTC, the arrival of the CMEs observed after the X flares on March 7. The initial part of the geomagnetic disturbance was much weaker than expected. Although it is unpredictable what happens when two CMEs interact, it isn't unusual that the magnetic fields carried along by the CMEs are partly neutralized in the merge process. The disturbance has intensified early on March 9 with major storm conditions observed 01-04h UTC.

Solar flux measured at 20h UTC on 2.8 GHz was 139.5 (increasing 28.7 over the last solar rotation). The planetary A index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 27.5). Three hour interval K indices: 21155643 (planetary), 10155533 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight UTC the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).

Region 11428 [S17W17] added some spots while the main penumbra split into smaller penumbrae. The region has weak polarity intermixing. A minor M class flare is possible. Flare: C7.2 at 02:53 UTC
Region 11429 [N17E03] lost penumbral area with the main penumbra fragmenting into smaller penumbrae. The region still has several magnetic delta structures and could produce further major flares. The region was the source of a long duration major M6.3 event peaking at 03:53 UTC on March 9. STEREO-B indicates that another full halo CME was produced by this event.
Region 11430 [N21W13] decayed with the leading penumbra splitting into smaller penumbrae. There's only rudimentary penumbra left on the trailing spots.
Region 11431 [S28W74] was quiet and stable.

Spotted regions not reported by NOAA/SWPC:
[S1515] rotated into view at the northeast limb on March 8. The region appears to have a magnetic delta structure. Location at midnight: N15E82
[S1516] emerged to the north of AR 11429 on March 8 with a single, diffuse spot. Location at midnight: N27E07

Minor update added at 11:10 UTC: As expected the CME earlier today was full halo in LASCO imagery. The current disturbance appears to be peaking at Kp 8. The planetary A index for the 07-10h UTC interval was 207 compared to 179 (Kp 8) one hour earlier. The very severe disturbance was caused by the interplanetary magnetic field being steadily strongly southwards for several hours. Over the last hour the IMF total field has weakened a bit and the southward orientation is not quite as strong.

One magnetic delta structure was gone in region 11429 after the LDE and the center of the region is becoming quite open. Several new ARs had spots at 10:00 UTC, see the most recent high resolution CHARMAP. S1517 was located at S23E33, S1518 at S26E23 while S1519 was at N06W25. AR 11431 has developed slowly today, and there is spot development in the southern part of region 1428 as well.

Minor update added at 20:30 UTC: AR S1515 at the east limb produced a C9.7 flare at 20:25 UTC. This region has all spots inside a single penumbra, and is a beta-delta region. Minor M class flares are possible. The disturbance that started yesterday is quickly decreasing in intensity. While max Ap was 207 for the 07-10, 08-11 and 10-13h UTC intervals, the IMF has weakened a lot and the most recent 3-hour interval has Ap at 12 (Kp 3).

Coronal mass ejections (CMEs)

March 6, 8: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
March 7: The X flares in region 11429 produced full halo CMEs which reached Earth on March 8.
March 9: The M6 event in region 11429 appears to have produced a full halo CME. This CME could reach Earth during the latter half of March 10 or early on March 11.

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

A large recurrent trans equatorial coronal hole (CH507) will likely rotate in an Earth facing position on March 13-14.

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.


Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is very poor to useless. Propagation on long distance northeast-southwest paths is poor.


The geomagnetic field is expected to be unsettled to severe storm on March 9 and quiet to active initially on March 10. Late on March 10 or early on March 11 another CME impact is likely and could cause active to severe storm conditions.

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
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
2K 1K
S1500 2012.02.29       N10W39           plage
S1505 2012.03.02       S27W27           plage
11428 2012.03.02
8 25 13 S17W19 0180 DAO DAI beta-gamma

area: 0300

location: S17W17

11429 2012.03.02
28 56 29 N17E01 0950 EKC EKC beta-gamma-delta

area: 1400

location: N17E03

reversed polarities

S1509 2012.03.03       S10W39           plage
11430 2012.03.04 8 21 13 N21W13 0180 DAO DAO  
11431 2012.03.04
2 2 1 S28W76 0020 CRO HRX  
S1512 2012.03.05       S17E10         plage
S1513 2012.03.07       S22E33         plage
S1514 2012.03.07       N12E24         plage
S1515 2012.03.08   2 1 N15E82 0080   DAO   beta-delta?
S1516 2012.03.08   1   N27E07 0000   AXX    
Total spot count: 46 107 57  
Sunspot number: 86 167 107  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 69 135 85  (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): 52 58 59 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
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
2010.12 84.2 14.4 28.8 (+2.3) 3.41 / 4.35
2011.01 83.6 19.1 31.0 (+2.2) 4.32 / 5.51
2011.02 94.6 29.4 33.4 (+2.4) 5.41 / 6.44
2011.03 115.0 56.2 36.9 (+3.5) 7.79 / 8.18
2011.04 112.6 54.4 41.8 (+4.9) 9.71 / 8.83
2011.05 95.8 41.6 47.6 (+5.8) 9.18 / 8.94
2011.06 95.8 37.0 53.2 (+5.6) 8.96 / 8.06
2011.07 94.2 43.9 57.2 (+4.0) 9.14 / 8.16
2011.08 101.7 50.6 59.0 (+1.8) 8.16 / 7.26
2011.09 133.8 78.0 (59.2 projected, +0.2) 12.80 / 12.27
2011.10 137.3 88.0 (59.4 projected, +0.2) 7.52 / 8.28
2011.11 153.5 96.7 (60.8 projected, +1.4) 4.58 / 5.55
2011.12 141.3 73.0 (63.6 projected, +2.8) 3.32
2012.01 132.5 58.3 (67.1 projected, +3.5) 6.59
2012.02 106.5 33.1 (71.0 projected, +3.9) 8.09
2012.03 123.5 (1) 18.5 (2A) / 71.5 (2B) (73.2 projected, +2.2) (19.72)

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.