Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 22, 2012 at 04:55 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 21, 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 March 21. Solar wind speed at SOHO ranged between 350 and 403 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 99.9 (decreasing 3.4 over the last solar rotation). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.5). Three hour interval K indices: 21122132 (planetary), 10122221 (Boulder).

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

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11433 [N09W69] decayed slowly and quietly.
Region 11434 [S21W77] decayed slowly and quietly.
Region 11436 [S13W04] was quiet and stable.
Region 11438 [S15E57] was quiet and stable.
New region 11440 [S26W25] emerged on March 19 and was assigned a number by SWPC two days later. The region developed on March 21 and has polarity intermixing. There's rudimentary penumbra between two nearby opposite polarity trailing spots. If the region develops further there will be a chance of M class flaring. Flares: C2.9 at 12:52, C1.2 at 13:59, C1.1 at 15:50 UTC.

Spotted regions not reported by NOAA/SWPC:
[S1537] reemerged on March 21 with several spots. Location at midnight: S28W42
[S1539] emerged in the northeast quadrant on March 20. Location at midnight: N05E12
[S1540] emerged near the northeast limb on March 21. Location at midnight: N13E65
[S1541] rotated into view at the northeast limb on March 21. Location at midnight: N16E78
[S1542] emerged in the southwest quadrant on March 21. Location at midnight: S17W32

AR 11432 at the northwest limb produced a low level C (estimated magnitude C1.5) class event at 22:25 UTC. With GOES x-ray monitoring currently not available, AIA 094 and 131 were used to determine the time and approximate magnitude of the flare.

Coronal mass ejections (CMEs)

March 19-21: 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 coronal hole (CH508) in the southern hemisphere was in an Earth facing position on March 20. CH508 decayed and almost closed on March 20-21 due to emerging AR 11440. A recurrent coronal hole (CH509) in the northern hemisphere will likely rotate into an Earth facing position on March 25.

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 to fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on March 22. A high speed stream from CH508 could cause quiet to unsettled conditions on March 23-24.

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
11434 2012.03.10
2012.03.11
2 3 2 S22W77 0050 CSO HRX

area: 0020

11433 2012.03.10
2012.03.11
1 1 1 N09W69 0020 HSX HRX  
11435 2012.03.11
2012.03.15
2     S24W90 0070 HSX     rotated out of view
11436 2012.03.15
2012.03.16
  1   S14W06 0000   AXX location: S13W04
S1529 2012.03.15       N14W47           plage
11437 2012.03.16
2012.03.17
      S34W41           plage
S1531 2012.03.17       N06W58           plage
S1533 2012.03.18       N23E10           plage
S1534 2012.03.18       N13W00           plage
11438 2012.03.19
2012.03.20
2 3 2 S14E56 0070 HSX HSX  
11440 2012.03.19
2012.03.21
5 16 12 S26W24 0030 DAI DRI beta-gamma
S1537 2012.03.19   3 1 S28W42 0000   BXO    
S1539 2012.03.20   3   N05E12 0000   BXO  
S1540 2012.03.21   1 1 N13E65 0010   HRX    
S1541 2012.03.21   1 1 N16E78 0010   HRX    
S1542 2012.03.21   1   S17W32 0000   AXX    
Total spot count: 12 33 20  
Sunspot number: 62 133 90  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 37 53 40  (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): 37 47 50 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
 
2010.12 84.2 14.4 28.8 (+2.3) 4.35
2011.01 83.6 19.1 31.0 (+2.2) 5.51
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 (59.2 projected, +0.2) 12.27
2011.10 137.3 88.0 (59.4 projected, +0.2) 8.28
2011.11 153.5 96.7 (60.8 projected, +1.4) 5.55
2011.12 141.3 73.0 (63.6 projected, +2.8) 3.78
2012.01 132.5 58.3 (67.1 projected, +3.5) 7.15
2012.02 106.5 33.1 (71.0 projected, +3.9) 8.81
2012.03 118.8 (1) 52.2 (2A) / 77.0 (2B) (73.2 projected, +2.2) (24.91)

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 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.