Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 29, 2013 at 06:45 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update March 1, 2013)] [Cycle 24 progress (last update March 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated March 24, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to active on March 28. Solar wind speed at SOHO ranged between 352 and 497 km/s. A high speed stream associated with CH562 became the dominant solar wind source during the afternoon and evening hours of the day, the disturbance associated with this stream has become stronger early on March 29.

Solar flux measured at 20h UTC on 2.8 GHz was 98.7 (decreasing 12.3 over the last solar rotation). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.3). Three hour interval K indices: 41121322 (planetary), 41122322 (Boulder).

The background x-ray flux was at the class B3 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11704 [N15E06] was quiet and stable.
Region 11705 [S12W22] decayed slowly and quietly.
Region 11706 [S07W09] decayed slowly and quietly.
New region 11707 [S11E32] emerged quickly. Further development will increase trhe likelihood of C and perhaps minor M class flares.
New region 11708 [N11E72] rotated into view on March 27 and was numbered by SWPC the next day. C flares are possible.

Spotted regions not numbered by SWPC:
S2314 [S18E38] reemerged with penumbra spots.
S2316 [S32W08] developed slowly and quietly.
New region S2320 [S22E60] emerged with several spots.
New region S2321 [S15E65] emerged with penumbra spots.
New region S2322 [S14E16] emerged with a single spot.
New region S2323 [S12W12] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

March 26-28: 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 recurrent trans equatorial coronal hole (CH562) was in an Earth facing position on March 25-27. A recurrent northern hemisphere coronal hole (CH563) was in an Earth facing position on March 28.

Coronal hole map

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 to good.

Forecast

The geomagnetic field is expected to be quiet to active on March 29-31 due to effects from CH562/563.

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 2K resolution) Compare to the previous day's image. 0.5k image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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
S2310 2013.03.22       S22W37           plage
11704 2013.03.23 1 9 3 N15E06 0090 HAX CSO area: 0120
11705 2013.03.24
2013.03.25
  2   S12W24 0004   BXO location: S12W22
S2314 2013.03.25   2 1 S18E38 0008   AXX    
11706 2013.03.26
2013.03.27
2 2 2 S06W09 0010 BXO BXO  
S2316 2013.03.26   7 6 S32W08 0030   AXX  
11708 2013.03.27
2013.03.28
2 6 3 N12E71 0050 CSO CAO  
S2318 2013.03.27       N16W24         plage
S2319 2013.03.27       S55W52         plage
11707 2013.03.28 4 13 7 S11E32 0020 BXO DRI   area: 0070
S2320 2013.03.28   6 2 S22E60 0016   BXO    
S2321 2013.03.28   2 2 S15E65 0010   BXO    
S2322 2013.03.28   1   S14E16 0001   AXX    
S2323 2013.03.28   1   S12W12 0002   AXX    
Total spot count: 9 51 26  
Sunspot number: 49 161 106  (total spot count + 10 * number of spotted regions)
Weighted SN: 19 64 39  (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): 29 56 58 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 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)
2011.11 153.5 (cycle max) 96.7 (cycle max) 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 65.5 (+2.1) 7.15
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.03 114.7 64.3 66.8 (-0.1) 16.08
2012.04 113.0 55.2 64.6 (-2.2) 10.10
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 57.7 (-1.2) 13.90
2012.08 115.4 63.0 58.1 (+0.4) 7.96
2012.09 122.9 61.4 (57.9 projected, -0.2) 8.07
2012.10 123.3 53.3 (57.0 projected, -0.9) 9.97
2012.11 121.3 61.4 (56.1 projected, -0.9) 7.08
2012.12 108.6 40.8 (54.9 projected, -1.2) 3.44
2013.01 127.1 62.9 (53.6 projected, -1.3) 4.69
2013.02 104.3 38.0 (52.5 projected, -1.1) 6.11
2013.03 111.6 (1) 73.8 (2A) / 81.7 (2B) / 50.8 (2C) (51.5 projected, -1.0) (9.28)

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) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
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.