Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 12, 2013 at 05:20 UTC.

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

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated June 30, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet to minor storm on July 11. Solar wind speed at SOHO ranged between 336 and 463 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 113.4 (increasing 4.3 over the last solar rotation). The Potsdam WDC planetary A index was 18 (STAR Ap - based on the mean of three hour interval ap indices: 18.0). Three hour interval K indices: 23433352 (planetary), 55453343 (Boulder).

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

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

Region 11785 [S13W60] decayed further and produced a few low level C flares.
Region 11787 [S14W35] decayed slowly and quietly.

Spotted regions not numbered by SWPC:
S2536 [S28W22] was quiet and stable. USAF/SWPC unfortunately reassigned spotless AR 11789 to this region despite a significant distance between the ARs.
S2539 [S17E63] was quiet and stable.
S2540 [N16E08] was quiet and stable.
S2541 [N04E71] was quiet and stable.
New region S2542 [S14E02] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

July 10-11: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
July 9: A filament eruption in the northern central hemisphere began near 14h UTC and was associated with a faint full halo CME.

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

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 active on July 12-13 due to effects from the July 9 CME and quiet on July 14.

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
11783 2013.06.29
2013.06.30
      N07W87          

plage

11785 2013.07.01 39 36 15 S13W57 0240 EAI DSI  
11788 2013.07.01
2013.07.05
      S15W66           merged with AR 11787
S2523 2013.07.02       S23W54            
11787 2013.07.02
2013.07.03
14 26 11 S15W36 0100 ESI EAO beta-gamma
S2525 2013.07.02       N11W50           plage
S2526 2013.07.02       N05W56           plage
11789 2013.07.06
2013.07.07
2     S28W24 0010   AXX     plage

location: S23W33

see AR S2536

11790 2013.07.06
2013.07.07
      S15W12           plage
S2534 2013.07.06       N17W14         images/AR_S2534_20130710_2345.jpg plage
S2536 2013.07.07   3 2 S28W22 0011   BXO  
S2537 2013.07.07       N22W04           plage
S2539 2013.07.10   6 2 S17E63 0025   BXO  
S2540 2013.07.10   2   N16E08 0004   AXX  
S2541 2013.07.10   3 3 N04E71 0010   AXX  
S2542 2013.07.11   1   S14E02 0002   AXX    
Total spot count: 55 77 33  
Sunspot number: 85 147 83  (total spot count + 10 * number of spotted regions)
Weighted SN: 65 87 43  (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): 51 51 46 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 peak) 96.7 (cycle peak) 61.1 (+1.2) 5.55
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
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 58.1 (-0.0) 8.07
2012.10 123.3 53.3 58.6 (+0.5) 9.97
2012.11 121.3 61.8 59.7 (+1.1) 7.08
2012.12 108.6 40.8 59.6 (-0.1) 3.44
2013.01 127.1 62.9 (58.7 projected, -0.9) 4.69
2013.02 104.3 38.0 (58.3 projected, -0.4) 6.11
2013.03 111.3 57.9 (57.9 projected, -0.4) 10.56
2013.04 124.8 72.4 (57.5 projected, -0.4) 5.40
2013.05 131.4 78.7 (57.6 projected, +0.1) 9.73
2013.06 110.1 52.5 (57.9 projected, +0.3) 12.60
2013.07 123.2 (1) 37.0 (2A) / 104.4 (2B) / 62.2 (2C) (58.0 projected, +0.1) (9.78)

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 the 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.