Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 28, 2014 at 06:40 UTC. The July 29 update is delayed and will be posted later today.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update July 1, 2014)] [Cycle 24 progress (last update July 1, 2014) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 1, 2014)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 1, 2014)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 5, 2014)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated July 18, 2014]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet on July 27. Solar wind speed at SOHO ranged between 316 and 354 km/s. What is likely a weak CME reached Earth early on July 28 and could cause some unsettled intervals during the day.

Solar flux at 20h UTC on 2.8 GHz was 121 (decreasing 19.5 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 132.6. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 21111111 (planetary), 22112421 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 193) and 9 active regions using 1K resolution (SN: 145) SDO images on the visible solar disk.

Region 12121 [N08E02] decayed slowly and quietly.
Region 12123 [S14E03] has weak polarity intermixing. C class flaring is possible.
Region 12124 [S21E49] was quiet and stable.
Region 12125 [S13E57] was mostly quiet and stable.
Region 12126 [S09E02] developed further and has polarity intermixing. C flares are possible.
New region 12127 [S08E75] rotated into view and has a weak magnetic delta structure in the largest penumbra.
New region 12128 [S21E75] rotated into view with a single spot.

Spotted regions not numbered (or interpreted differently) by SWPC:
New region S3674 [S06E07] emerged early in the day to the northeast of AR 12126.
New region S3677 [N02W18] emerged with penumbra spots.
New region S3678 [S32W11] was observed with a penumbra spot.

C2+ Flares (GOES):

Magnitude Peak time (UTC) Location AR
C2.5 05:51 S12E71 12125

Coronal mass ejections (CMEs)

July 25-27: 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 significant 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 upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.

Forecast

The geomagnetic field is expected to be quiet on July 27-30.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12121 2014.07.21
2014.07.22
12 20 10 N08E04 0130 CAO CSO

area: 0230

location: N08E02

12122 2014.07.21
2014.07.22
      S13W19        

plage

location: S12W13

S3663 2014.07.22       N20W48           plage
12123 2014.07.22
2014.07.23
9 11 7 S14W00 0040 CAO DAO beta-gamma

area: 0070

location: S14E03

S3665 2014.07.22       N12W42           plage
S3667 2014.07.24       N09W52           plage
12126 2014.07.24
2014.07.26
10 23 15 S10E03 0050 DAO DAI beta-gamma

location: S09E02

area: 0140

S3669 2014.07.24       S12W56           plage
12124 2014.07.25
2014.07.26
1 5 1 S22E49 0010 AXX AXX  
12125 2014.07.25
2014.07.26
4 7 4 S13E57 0040 CAO DAO area: 0080
S3672 2014.07.26       N20W16         plage
S3673 2014.07.26       S14E40         plage
12127 2014.07.27 3 6 5 S08E75 0080 DAO DKC   beta-delta

area: 0300

12128 2014.07.27 1 1 1 S21E75 0030 HRX HSX   area: 0050
S3674 2014.07.27   17 11 S06E07 0090   DRI    
S3677 2014.07.27   2 1 N02W18 0005   AXX    
S3678 2014.07.27   1   S32W11 0002   AXX    
Total spot count: 40 93 55  
Sunspot number: 110 193 145  (total spot count + 10 * number of spotted regions)
Weighted SN: 68 131 93  (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): 66 68 80 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2013.02 104.3 101.8 38.0 58.4 (-0.3) 6.11
2013.03 111.3 110.2 57.9 57.5 (-0.9) 10.56
2013.04 124.8 125.9 72.4 57.9 (+0.4) 5.40
2013.05 131.4 134.3 78.7 59.9 (+2.0) 9.73
2013.06 110.1 113.7 52.5 62.6 (+2.7) 12.60
2013.07 115.5 119.3 57.0 65.5 (+2.9) 9.47
2013.08 114.6 118.3 66.0 69.0 (+3.5) 8.27
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 (78.2 projected, +2.2) 5.44
2014.02 170.3
(cycle peak)
166.3 102.3 (cycle peak) (79.7 projected, +1.5) 10.70
2014.03 149.9 148.5 91.9 (80.5 projected, +0.8) 4.88
2014.04 143.9 144.8 84.7 (79.7 projected, -0.8) 7.88
2014.05 129.7 132.9 75.2 (77.1 projected, -2.6) 5.75
2014.06 122.0 125.8 71.0 (74.5 projected, -2.6) 6.72
2014.07 136.2 (1)   95.4 (2A) / 109.5 (2B) / 83.0 (2C) (71.5 projected, -3.0) (4.4)

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 WDC-SILSO 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 GFZ 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.