Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 15, 2013 at 04:30 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 unsettled to minor storm on July 14. Solar wind speed at SOHO ranged between 347 and 397 km/s. The disturbance that began on July 12 intensified as the interplanetary magnetic field swung moderately southwards after 07h and stayed that way until 23h UTC. Since then the IMF has continued southwards but with a weaker total field.

Solar flux measured at 20h UTC on 2.8 GHz was 112.9 (decreasing 10.9 over the last solar rotation). The Potsdam WDC planetary A index was 24 (STAR Ap - based on the mean of three hour interval ap indices: 23.8). Three hour interval K indices: 33345453 (planetary), 33344433 (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 11791 [S14E22] developed a magnetic delta structure in the northern part of the largest penumbra. An M class flare is possible. The region was the source of a long duration C3 event peaking near 03:40 UTC on July 15. The associated CME may have an Earth directed component.
Region 11792 [N02E28] was quiet and stable.
New region 11793 [N19E79] rotated fully into view. The region could produce C and perhaps M class flares.
New region 11794 [N15W57] emerged on July 13 and received its NOAA number the next day.
New region 11795 [S06E66] rotated into view on July 13 and was numbered by SWPC the next day.

Spotted regions not numbered by SWPC:
S2543 [S22E10] reemerged with penumbra spots.
S2545 [S24E49] was quiet and stable.

Coronal mass ejections (CMEs)

July 12-14: 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 recurrent coronal hole (CH575) in the northern hemisphere will likely rotate into an Earth facing position on July 14-18.

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 minor storm on July 15. On July 16 a corotating interaction region associated with CH575 could cause unsettled to major storm conditions. This disturbance could extend to July 21, 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
11787 2013.07.02
2013.07.03
1     S13W75 0020 HAX     spotless
11789 2013.07.06
2013.07.07
      S27W65           plage
11790 2013.07.06
2013.07.07
      S15W54           plage
S2534 2013.07.06       N21W52           plage
S2537 2013.07.07       N22W43           plage
11791 2013.07.10
2013.07.12
15 27 14 S15E17 0110 DAI DAC beta-gamma-delta

location: S14E22

area: 0210

S2540 2013.07.10       N17W29           plage
11792 2013.07.10
2013.07.12
5 5 2 N04E29 0010 BXO BXO area: 0030

location: N02E28

S2542 2013.07.11       S14W37           plage
S2543 2013.07.12   6   S22E10 0008   AXX    
S2544 2013.07.12       N10E16           plage
S2545 2013.07.13   2   S24E49 0006   AXX  
11795 2013.07.13
2013.07.14
2 4 1 S06E64 0010 BXO AXX area: 0017
11793 2013.07.13
2013.07.14
3 10 5 N19E74 0150 DHO ESI location: N19E79

area: 0400

11794 2013.07.13
2013.07.14
2 6 2 N13W57 0010 BXO DRO location: N15W57

area: 0040

Total spot count: 28 60 24  
Sunspot number: 88 130 74  (total spot count + 10 * number of spotted regions)
Weighted SN: 48 73 37  (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): 53 46 41 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
2013.07 121.4 (1) 44.8 (2A) / 99.2 (2B) / 62.2 (2C) (58.0 projected, +0.1) (10.48)

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.