Last major update issued on September 11, 2013 at 04:55 UTC.
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The geomagnetic field was quiet to unsettled on September 10. Solar wind speed at SOHO ranged between 285 and 404 km/s. A low speed stream associated with CH584 was observed beginning after 10h UTC at SOHO.
Solar flux measured at 20h UTC on 2.8 GHz was 94.9 (decreasing 30.3 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: 6.3). Three hour interval K indices: 00022332 (planetary), 00032322 (Boulder).
The background x-ray flux was at the class B1 level.
At the time of counting spots (see image time) there were 9 active regions in 2K resolution (SN: 126) and 4 active regions in 1K resolution (SN: 48) SDO images with spots on the visible solar disk.
Region 11838 [S05E05] decayed slowly and quietly.
New region 11839 [S12W27] emerged with several
spots.
Spotted regions not numbered by SWPC:
S2658 [S12E10] developed slowly and quietly.
S2665 [S15W05] was quiet and stable.
New region S2667 [S13E39] emerged with penumbra spots in an old
plage area.
New region S2668 [S05E83] rotated into view.
New region S2669 [N13E57] emerged with penumbra spots in an old plage
area.
New region S2670 [N05W33] emerged with a few
penumbra spots.
New region S2671 [S28W06] emerged with a penumbra spot in an old
plage area.
September 8-10: 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 (CH584) in the northern hemisphere was in an Earth facing position on September 7. CH584 is the western part of what used to be a large coronal hole and has slowly decreased in size after rotating into view. The eastern part of that large coronal hole, now CH585, will be in an Earth facing position on September 9-11.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to unsettled on September 11 due to effects from CH584. Effects from CH585 could cause quiet to minor storm conditions on September 12-14.
| 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 |
1 | 6 | S04E02 | 0000 | AXX | BXO |
 |
 |
location: S05E05 |
|
| S2658 | 2013.09.05 | 10 | 4 | S12E10 | 0035 | DRO |
 |
 |
|||
| S2660 | 2013.09.05 | N13W45 | plage | ||||||||
| S2661 | 2013.09.05 | S22W14 |
 |
plage | |||||||
| S2662 | 2013.09.06 | N07W54 | plage | ||||||||
| S2664 | 2013.09.08 | S03W28 | plage | ||||||||
| S2665 | 2013.09.08 | 2 | 1 | S15W05 | 0007 | AXX |
 |
 |
|||
| S2666 | 2013.09.09 | S18W43 |
 |
plage | |||||||
| 11839 | 2013.09.10 | 2 | 6 | 2 | S13W27 | 0010 | HRX | DRO |
 |
area: 0030 | |
| S2667 | 2013.09.10 | 3 | S13E39 | 0003 | AXX |
 |
|||||
| S2668 | 2013.09.10 | 1 | S05E83 | 0020 | HRX |
 |
|||||
| S2669 | 2013.09.10 | 4 | N13E57 | 0005 | BXO |
 |
|||||
| S2670 | 2013.09.10 | 3 | 1 | N05W33 | 0009 | BXO |
 |
||||
| S2671 | 2013.09.10 | 1 | S28W06 | 0003 | AXX |
 |
|||||
| Total spot count: | 3 | 36 | 8 | ||||||||
| Sunspot number: | 23 | 126 | 48 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 6 | 42 | 14 | (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): | 14 | 44 | 26 | 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 | 102.0 (1) | 17.2 (2A) / 51.7 (2B) / 51.0 (2C) | (57.8 projected, -0.4) | (5.28) |
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.
