Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 24, 2013 at 04:50 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 on July 23. Solar wind speed at SOHO ranged between 347 and 373 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 106.7 (increasing 0.2 over the last solar rotation). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 21011111 (planetary), 22111322 (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 11793 [N20W40] decayed slowly and quietly.
Region 11795 [S04W57] remerged with a penumbra spot.
Region 11799 [S18W03] decayed slowly and quietly.
Region 11800 [S07W04] developed as new flux emerged in the northern part. A split is being considered for the southeastern spot section.
New region 11801 [N20E71] rotated into view on July 22 and was numbered by SWPC the next day.
New region 11802 [N13W47] emerged on July 22 and got a NOAA number the next day.
New region 11803 [S09E12] emerged on July 18 and was numbered by SWPC 5 days later.

Spotted regions not numbered by SWPC:
S2550 [S19W60] reemerged with a penumbra spot.
New region S2565 [S12E77] rotated into view with a single spot.
New region S2566 [S13E37] emerged with penumbra spots.
New region S2567 [N21E22] emerged with penumbra spots in an old plage area.

Coronal mass ejections (CMEs)

July 21-23: 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 (CH576) was in an Earth facing position on July 22-23.

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 poor.

Forecast

The geomagnetic field is expected to be quiet on July 24. A high speed stream from CH576 could cause quiet to active conditions on July 25-26.

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
11797 2013.07.13
2013.07.17
      S19W68           plage
11795 2013.07.13
2013.07.14
  1   S06W69         location: S04W57
11793 2013.07.13
2013.07.14
5 14 4 N20W40 0110 ESO ESO

area: 0140

S2550 2013.07.15   1   S19W60 0004   AXX    
11798 2013.07.17
2013.07.18
      S12W28           plage
11799 2013.07.17
2013.07.18
1 1   S16W04 0010 AXX AXX area: 0003
11800 2013.07.17
2013.07.18
9 29 14 S07W03 0050 DSO DAI  
11803 2013.07.18
2013.07.23
6 9   S09E11 0010 BXO BXO  
S2559 2013.07.19       S13W49           plage
S2560 2013.07.19       N18W15           plage
S2562 2013.07.20       S32W56           plage
11801 2013.07.22
2013.07.23
1 1 1 N20E66 0060 HSX HSX location: N20E71
11802 2013.07.22
2013.07.23
2 4 2 N14W47 0010 BXO BXO  
S2565 2013.07.23   1   S12E77 0004   AXX    
S2566 2013.07.23   2   S13E37 0003   AXX    
S2567 2013.07.23   4   N21E22 0004   AXX    
Total spot count: 24 67 21  
Sunspot number: 84 177 61  (total spot count + 10 * number of spotted regions)
Weighted SN: 39 82 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): 50 62 34 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
2013.07 117.7 (1) 66.1 (2A) / 89.1 (2B) / 54.9 (2C) (58.0 projected, +0.1) (10.23)

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.