Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 15, 2013 at 04:55 UTC. Minor update posted at 16:30 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 February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on March 14. Solar wind speed at SOHO ranged between 276 and 419 km/s. Solar wind speed increased slowly after noon, likely due to the arrival of a low speed stream from CH559. The interplanetary magnetic field was mostly northwards resulting in only a minor increase in geomagnetic activity. A weak solar wind shock was observed near 04:40 UTC on March 15, the likely arrival of a CME observed on March 12.

Solar flux measured at 20h UTC on 2.8 GHz was 122.8 (increasing 19.6 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.8). Three hour interval K indices: 11112111 (planetary), 01013222 (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 11689 [S18W71] decayed slowly and quietly.
Region 11690 [N24W35] was quiet and stable.
Region 11691 [N12W40] decayed slowly with polarity intermixing disappearing during the day.
Region 11692 [N09E10] was quiet and stable.
Region 11694 [N15E12] was quiet and stable.
Region 11695 [N09E33] was quiet and stable.
Region 11696 [N04W08] decayed slowly and quietly.
New region 11697 [N14W22] emerged on March 13 and was numbered the next day by SWPC.
New region 11698 [S19W29] emerged quickly and has polarity intermixing.

Spotted regions not numbered by SWPC:
S2278 [S16W46] lost the spots from the previous day and gained a spot further west.
New region S2291 [S13W26] emerged with penumbra spots.

Update added at 16:30 UTC on March 15: AR 11692 produced a long duration M1.1/1F event peaking at 06:58 UTC. This event was associated with a large and wide full halo CME in STEREO A/B and LASCO. The CME could reach Earth on March and cause minor to severe geomagnetic storming.

Coronal mass ejections (CMEs)

March 12: A weak partial halo CME was observed in LASCO imagery from the combined ejecta of the C2 LDE near the central meridian and a filament eruption in the northeast quadrant. The CME may have had a weak Earth directed component.
March 13: A CME was observed off the east limbs early in the day following a filament eruption near ARs 11696 and 11692 late on March 12. No obvious Earth bound components were observed.
March 14: 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 small northern hemisphere coronal hole (CH559) was in an Earth facing position on March 11. A small coronal hole (CH560) in the southern hemisphere was Earth facing on March 14 but seemed to be closing by the end of the day.

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

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 15 due with a chance of active intervals if the CME observed on March 12 arrives. Quiet to unsettled consitions are likely on March 16-17. A few unsettled intervals are possible on March 18 due to effects from CH560.

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
11687 2013.03.02
2013.03.03
      N08W79        

plage

11689 2013.03.03
2013.03.04
4 5 3 S18W69 0030 CRO BXO  
11690 2013.03.06 2 2   N25W36 0010 BXO BXO  
11693 2013.03.06
2013.03.10
      N18W88           plage
11691 2013.03.07
2013.03.08
8 18 6 N13W39 0120 DAO DSO area: 0190

location: N12W40

S2278 2013.03.08   1   S16W46 0002   AXX  
11692 2013.03.09 2 10 2 N09E09 0200 HSX CHO

area: 0330

11694 2013.03.09
2013.03.10
1 7 3 N15E11 0020 HRX CRO  
S2284 2013.03.09       N27W58           plage
11695 2013.03.10
2013.03.11
1 3 1 N09E31 0160 HSX CSO area: 0230

location: N09E33

11696 2013.03.11 15 14 6 N05W09 0150 EAI ESO beta-gamma

area: 0270

location: N04W08

S2286 2013.03.11       N09W30           plage
S2287 2013.03.12       S25E57         plage
S2288 2013.03.12       N13W25           plage
11697 2013.03.13
2013.03.14
4 9 5 N15W22 0030 CRO DRO  
S2290 2013.03.13       N17W53         plage
11698 2013.03.14 6 15 5 S20W29 0020 CRO DAO   area: 0060
S2291 2013.03.14   2   S13W26 0005   AXX    
Total spot count: 43 86 31  
Sunspot number: 133 196 111  (total spot count + 10 * number of spotted regions)
Weighted SN: 75 122 67  (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): 80 69 61 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
2013.03 116.8 (1) 42.5 (2A) / 94.1 (2B) / 48.8 (2C) (51.5 projected, -1.0) (7.29)

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.