Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 15, 2012 at 04:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update May 3, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update May 3, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update May 3, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 3, 2012)]

[POES auroral activity level since October 2009 - updated May 12, 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 unsettled on May 14. Solar wind speed at SOHO ranged between 424 and 514 km/s weakly under the influence of a high speed stream from CH516.

Solar flux measured at 20h UTC on 2.8 GHz was 130.0 (increasing 16.2 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.5). Three hour interval K indices: 32111112 (planetary), 22111212 (Boulder).

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

At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).

Region 11476 [N10W48] decayed further with only traces of rudimentary penumbra remaining on the trailing spots. An M class flare is still a possibility.
Region 11477 [S23W05] was quiet and stable.
Region 11478 [S24E04] was quiet and stable.
Region 11479 [N13E27] was quiet and stable.
Region 11481 [S10E48] was quiet and stable.
Region 11482 [N13E36] decayed slowly and quietly.
Region 11483 [S27E39] developed slowly. The region currently has polarity intermixing. Rudimentary penumbra is observed on two narrowly spaced opposite polarity spots in the southeastern part of the region. Further C class flaring is possible.
Region 11484 [N12E79] developed slowly and quietly

Spotted active regions not numbered by NOAA/SWPC:
New region S1654 [S26E70] emerged near the southeast limb with a tiny spot.
New region S1655 [S17E36] emerged with tiny spots in an old plage field.
New region S1656 [S32W17] emerged with a tiny spot.
New region S1657 [S22W32] emerged with a tiny spot.
New region S1658 [S23W64] emerged with a single spot.

Coronal mass ejections (CMEs)

May 11-12: A filament eruption began after 18h UTC on May 11 and involved a large area around the center of the disk, including the southern part of AR 11476, AR 11480 and extending towards the east. A CME was observed in STEREO-B at 23:54 UTC and in STEREO-A a couple of hours later when images resumed. LASCO displays a slow and small halo CME. The CME is likely Earth directed.
May 13-14: No obviously Earth directed CMEs were observed in LASCO or 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

No obvious 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 to active on May 15 due to weak CME effects. Quiet conditions are likely on May 16-18.

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
11476 2012.05.04
2012.05.05
53 40 23 N09W46 0600 FKO FKI beta-gamma-delta
11477 2012.05.07
2012.05.08
4 4 1 S22W05 0040 HSX CSO

 

11478 2012.05.08
2012.05.10
4 2 1 S24E04 0070 HSX HSX area: 0120
11480 2012.05.08
2012.05.11
      S16W52           plage

location: S17W44

S1642 2012.05.09       S15W30           plage
11479 2012.05.10
2012.05.11
1 3 2 N14E26 0050 HSX CSO

area: 0090

S1645 2012.05.10       S12W30           plage
11482 2012.05.11
2012.05.13
4 11 7 N14E35 0050 CSO CSO area: 0090
S1647 2012.05.11       N13E02         plage
11483 2012.05.12
2012.05.13
7 21 6 S27E37 0010 BXO DRI beta-gamma

area: 0040

11481 2012.05.12
2012.05.13
1 3 1 S11E47 0020 HSX CSO area: 0040
11484 2012.05.13 2 10 8 N10E65 0010 BXO DSI beta-gamma

area: 0060

S1651 2012.05.13       N31E27         plage
S1652 2012.05.13       S03W18         plage
S1653 2012.05.13       N28W10         plage
S1654 2012.05.13   1   S26E70 0000   AXX    
S1655 2012.05.13   5 1 S17E36 0000   AXX    
S1656 2012.05.13   1 1 S32W17 0000   AXX    
S1657 2012.05.13   1 1 S22W32 0000   AXX    
S1658 2012.05.13   1 1 S23W64 0010   AXX    
Total spot count: 76 103 53  
Sunspot number: 156 233 173  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 98 146 96  (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): 94 82 95 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
 
2011.02 94.6 29.4 33.4 (+2.4)  6.44
2011.03 115.0 56.2 36.9 (+3.5) 8.18
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 (61.2 projected, +1.3) 5.55
2011.12 141.3 73.0 (63.9 projected, +2.7) 3.78
2012.01 132.5 58.3 (67.4 projected, +3.5) 7.15
2012.02 106.5 33.1 (71.4 projected, +4.0) 8.81
2012.03 114.7 64.2 (73.5 projected, +2.1) 16.08
2012.04 113.0 55.2 (74.5 projected, +1.0) 10.10
2012.05 122.5 (1) 46.1 (2A) / 102.1 (2B) (75.8 projected, +1.3) (10.48)

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.