Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 6, 2013 at 06:05 UTC. Irregular updates are likely until July 12.

[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 5. Solar wind speed at SOHO ranged between 318 and 383 km/s. A weak disturbance was in progress most of the day and intensified early on July 6. The most likely source is a co-rotating interaction region associated with a northern hemisphere coronal hole (which rotated across the central meridian several days ago).

Solar flux measured at 20h UTC on 2.8 GHz was 140.8 (increasing 37.6 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.0). Three hour interval K indices: 22222231 (planetary), 22322332 (Boulder).

The background x-ray flux was at the class B7 level.

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

Region 11784 [S16W21] matured and appeared to be decaying late in the day.
Region 11785 [S09E24] has many spots and 2 minor magnetic delta structures. A major flare is possible.
Region 11787 [S15E44] has minor polarity intermixing and could produce a minor M class flare. C5+ event: impulsive C8.5 flare at 13:01 UTC.

Spotted regions not numbered by SWPC:
S2521 [N12W18] was quiet and stable.
S2523 [S24E23] reemerged with penumbra spots.
S2525 [N10E08] reemerged with penumbra spots.
S2526 [N05E22] reemerged with penumbra spots.

Coronal mass ejections (CMEs)

July 3-5: 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

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 good.

Forecast

The geomagnetic field is expected to be quiet to active on July 6 due to effects from a corotating interaction region and quiet on July 7-8.

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
11779 2013.06.24
2013.06.25
      N17W84         plage
11782 2013.06.27
2013.06.28
      S15W51           plage
11783 2013.06.29
2013.06.30
      N07W12        

plage

11784 2013.06.30
2013.07.01
15 38 15 S16W23 0070 DAI DAI

area: 0100

11785 2013.07.01 42 86 52 S11E24 0720 EKC EKC beta-gamma-delta

area: 1200

location: S09E24

11786 2013.07.01
2013.07.02
      S31W25           plage
S2519 2013.07.01       S17W08           plage
11788 2013.07.01
2013.07.05
2     S15E18 0010 BXO     plage
S2521 2013.07.01   2 1 N12W18 0006   AXX  
S2522 2013.07.01       S21W31           plage
S2523 2013.07.02   2 1 S24E23 0004   AXX    
11787 2013.07.02
2013.07.03
14 42 23 S15E43 0170 EAI EAI beta-gamma

area: 0260

S2525 2013.07.02   6 3 N10E08 0016   BXO    
S2526 2013.07.02   2   N05E22 0004   AXX    
S2529 2013.07.02       N21W43         plage
S2531 2013.07.03       S16W31           plage
Total spot count: 73 178 95  
Sunspot number: 113 248 155  (total spot count + 10 * number of spotted regions)
Weighted SN: 93 198 115  (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): 68 87 85 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) 12.06
2013.07 125.0 (1) 16.7 (2A) / 103.8 (2B) / 55.5 (2C) (58.0 projected, +0.1) (4.58)

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.