Last major update issued on September 13, 2013 at 04:05 UTC.
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SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to unsettled on September 12. Solar wind speed at SOHO ranged between 339 and 449 km/s. A high speed stream from CH585 was observed beginning at SOHO near 18h UTC.
Solar flux measured at 20h UTC on 2.8 GHz was 92.9 (decreasing 27.0 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: 6.5). Three hour interval K indices: 31221123 (planetary), 21211223 (Boulder).
The background x-ray flux was at the class B1 level.
At the time of counting spots (see image time) there were 7 active regions in 2K resolution (SN: 112) and 6 active regions in 1K resolution (SN: 74) SDO images with spots on the visible solar disk.
Region 11838 [S05W22] decayed slowly and quietly.
Region 11839 [S12W54] developed slowly and was quiet.
Region 11840 [S12W17] decayed slowly and quietly.
Region 11841 [S05E57] gained a few spots and was quiet.
New region 11842 [N04W64] emerged on September 10 and was numbered by
SWPC 2 days later. The region decayed on September 12.
Spotted regions not numbered by SWPC:
S2674 [N13E21] was quiet and stable.
New region S2677 [S28E08] emerged with penumbra spots in an old
plage area.
September 10-12: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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 (CH585) in the northern hemisphere was in an Earth facing position on September 9-11. A trans equatorial coronal hole (CH586) will rotate into an Earth facing position on September 13.
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 to fair.
The geomagnetic field is expected to be quiet to active on September 13-14 and quiet to unsettled on September 15 due to effects from CH585. Effects from CH586 could cause quiet to active conditions on September 16-17.
| 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.
(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 | ||||||||||
| 11838 | 2013.09.04 2013.09.05 |
2 | 10 | 3 | S05W25 | 0010 | AXX | BXO |
 |
 |
location: S05W22 |
| 11840 | 2013.09.05 2013.09.11 |
2 | 6 | 1 | S11W19 | 0001 | AXX | BXO |
 |
 |
location: S12W17 |
| S2661 | 2013.09.05 | S22W40 | plage | ||||||||
| S2664 | 2013.09.08 | S03W54 | plage | ||||||||
| S2665 | 2013.09.08 | S15W31 | plage | ||||||||
| 11839 | 2013.09.10 | 1 | 12 | 5 | S12W52 | 0010 | BXO | CRO |
 |
 |
area: 0040 location: S12W54 |
| S2667 | 2013.09.10 | S18E24 |
 |
plage | |||||||
| 11841 | 2013.09.10 2013.09.11 |
1 | 6 | 3 | S06E54 | 0040 | CAO | CSO |
 |
 |
area: 0070 location: S05E57 |
| S2669 | 2013.09.10 | N13E31 | plage | ||||||||
| 11842 | 2013.09.10 2013.09.12 |
2 | 3 | 1 | N04W62 | 0020 | CRO | AXX |
 |
 |
area: 0010 |
| S2671 | 2013.09.10 | S32W36 |
 |
plage | |||||||
| S2672 | 2013.09.11 | S11W39 |
 |
plage | |||||||
| S2673 | 2013.09.11 | N08W29 |
 |
plage | |||||||
| S2674 | 2013.09.11 | 2 | 1 | N13E21 | 0006 | BXO |
 |
 |
|||
| S2675 | 2013.09.11 | N20E23 |
 |
plage | |||||||
| S2676 | 2013.09.11 | N24W11 |
 |
plage | |||||||
| S2677 | 2013.09.12 | 3 | S28E08 | 0005 | BXO |
 |
|||||
| Total spot count: | 8 | 42 | 14 | ||||||||
| Sunspot number: | 58 | 112 | 74 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 16 | 50 | 22 | (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): | 35 | 39 | 41 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K | |||||||
| 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) likely cycle 24 max |
8.81 |
| 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 | 57.8 (-1.1) | 13.90 |
| 2012.08 | 115.4 | 63.0 | 58.2 (+0.4) | 7.96 |
| 2012.09 | 122.9 | 61.4 | 58.1 (-0.1) | 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 (-0.9) | 4.69 |
| 2013.02 | 104.3 | 38.0 | 58.4 (-0.3) | 6.11 |
| 2013.03 | 111.3 | 57.9 | (58.2 projected, -0.2) | 10.56 |
| 2013.04 | 124.8 | 72.4 | (57.9 projected, -0.3) | 5.40 |
| 2013.05 | 131.4 | 78.7 | (58.0 projected, +0.1) | 9.73 |
| 2013.06 | 110.1 | 52.5 | (58.3 projected, +0.3) | 12.60 |
| 2013.07 | 115.5 | 57.0 | (58.3 projected, 0.0) | 9.47 |
| 2013.08 | 114.6 | 66.0 | (58.2 projected, -0.1) | 8.27 |
| 2013.09 | 100.4 (1) | 20.9 (2A) / 52.3 (2B) / 50.1 (2C) | (57.8 projected, -0.4) | (5.59) |
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.
