Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 13, 2012 at 05:15 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 severe storm on March 12. Solar wind speed at SOHO ranged between 394 and 748 km/s. The CME observed on March 10 arrived was observed reaching SOHO at 08:43 UTC. The interplanetary magnetic field was initially strong and southwards, then swung northwards for about an hour. The next 1.5 hours saw a sustained period with strong southwards Bz. This caused major to severe storming. Later on the IMF weakened and was mostly weakly southwards.

Solar flux measured at 17h UTC on 2.8 GHz was 130.3 (increasing 22.9 over the last solar rotation, the observation at 20h UTC was incorrect and much lower than the readings at 17 and 23h UTC). The planetary A index was 37 (STAR Ap - based on the mean of three hour interval ap indices: 37.4). Three hour interval K indices: 21267432 (planetary), 22267443 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11428 [S16W73] decayed further and could become spotless before rotating out of view.
Region 11429 [N18W52] decayed significantly losing many spots and penumbral area. As there is still a magnetic delta structure in the central spot region, there's a minor possibility of another major flare.
Region 11430 [N21W68] decayed slowly and was mostly quiet.
Region 11432 [N14E27] added many small spots. Currently the region has polarity intermixing, however, it is possible to interpret the southeastern part of the region as a separate region. If that spot section continues to develop the region could be split tomorrow.
Region 11433 [N11E50] developed slowly and has weak polarity intermixing.
Region 11434 [S22E57] decayed slowly and quietly.

Spotted regions not reported by NOAA/SWPC:
[S1524] emerged in the southeast quadrant on March 11. Location at midnight: S26E31

Coronal mass ejections (CMEs)

March 10: The M8 event in region 11429 was associated with an inpressive halo CME which reached Earth on March 12.
March 11-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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 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.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 13 due to weak CME effects, active intervals are possible. On March 14-15 quiet conditions are likely. A high speed stream from CH507 could cause unsettled to minor storm conditions on March 16-17.

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 magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11428 2012.03.02
2012.03.03
1 2   S15W72 0030 HSX AXX

 

11429 2012.03.02
2012.03.03
14 20 16 N18W50 0380 EKC EHC beta-gamma-delta

reversed polarities

location: N18W52

area: 0600

11430 2012.03.04 1 2 1 N22W67 0030 HSX HRX  
S1512 2012.03.05       S23W30           plage
S1514 2012.03.07       N12W28           plage
11432 2012.03.08
2012.03.09
9 28 14 N13E26 0080 DSO DRI beta-gamma

maybe two regions

S1516 2012.03.08       N27W45           plage
S1517 2012.03.09       S25W20          
S1520 2012.03.09       N27W17           plage
11434 2012.03.10
2012.03.11
2 4 2 S23E44 0050 CSO DSO  
11433 2012.03.10
2012.03.11
2 13 5 N11E50 0080 CSO CSO  
S1524 2012.03.11   1   S26E31 0000   AXX  
Total spot count: 29 70 38  
Sunspot number: 89 140 88  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 64 96 64  (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): 53 49 48 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
3.25
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
2012.03 128.0 (1) 30.6 (2A) / 79.1 (2B) (73.2 projected, +2.2) (26.28)

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.