Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 13, 2013 at 07:10 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 unsettled on July 12. Solar wind speed at SOHO ranged between 325 and 540 km/s. A weak solar wind shock was observed at 16:32 UTC at SOHO, likely the arrival of the CME observed on July 9.

Solar flux measured at 20h UTC on 2.8 GHz was 117.6 (increasing 7.6 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: 7.8). Three hour interval K indices: 22222223 (planetary), 13322223 (Boulder).

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

At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).

Region 11785 [S10W76] decayed slowly and was mostly quiet.
Region 11787 [S14W49] decayed slowly and was mostly quiet.
New region 11791 [S14E47] rotated into view on July 10 and was numbered by USAF/SWPC 2 days later.
New region 11792 [N04E57] rotated into view on July 10 and got its NOAA number 2 days later.

Spotted regions not numbered by SWPC:
S2534 [N21W26] reemerged with penumbra spots.
S2540 [N17W03] was quiet and stable.
New region S2543 [S26E42] emerged with penumbra spots in an old plage area.
New region S2544 [N10E42] emerged with penumbra spots.

Coronal mass ejections (CMEs)

July 10-12: 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 coronal hole (CH575) in the northern hemisphere will likely rotate into an Earth facing position on July 14-16.

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 13 due to effects from the July 9 CME and quiet on July 14-15. On July 16 a corotating interaction region associated with CH575 could cause unsettled to major storm conditions. This disturbance could extend to July 19, gradually decreasing in intensity.

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
11785 2013.07.01 12 8 4 S11W68 0080 ESO CRO area: 0030

location: S10W76

11788 2013.07.01
2013.07.05
      S15W80           merged with AR 11787
11787 2013.07.02
2013.07.03
14 14 8 S13W49 0090 EAO ERO  
11789 2013.07.06
2013.07.07
1     S27W37 0000   AXX     plage

location: S23W47

see AR S2536

11790 2013.07.06
2013.07.07
      S15W26           plage
S2534 2013.07.06   5 3 N21W26 0016   BXO    
S2536 2013.07.07       S28W35         plage
S2537 2013.07.07       N22W17           plage
11791 2013.07.10
2013.07.12
7 12 7 S15E47 0050 DSO DRO  
S2540 2013.07.10   2 1 N17W03 0005   AXX  
11792 2013.07.10
2013.07.12
3 7 3 N05E55 0010 BXO BXO  
S2542 2013.07.11       S14W11         plage
S2543 2013.07.12   3   S26E42 0004   BXO    
S2544 2013.07.12   3 1 N10E42 0005   AXX    
Total spot count: 37 54 27  
Sunspot number: 87 134 97  (total spot count + 10 * number of spotted regions)
Weighted SN: 52 63 36  (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): 52 47 53 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
2013.07 122.8 (1) 39.8 (2A) / 102.9 (2B) / 63.0 (2C) (58.0 projected, +0.1) (9.61)

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.