Last major update issued on September 21, 2013 at 04:55 UTC.
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September 5, 2013]
[Presentation
3rd
SSN Workshop, Tucson, 2013 (pdf)]
The geomagnetic field was quiet to unsettled on September 20. Solar wind speed at SOHO ranged between 379 and 518 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 109.2 (decreasing 8.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 114.3. The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.3). Three hour interval K indices: 22222113 (planetary), 12222112 (Boulder).
The background x-ray flux was at the class B3 level.
At the time of counting spots (see image time) there were 8 active regions in 2K resolution (SN: 129) and 6 active regions in 1K resolution (SN: 82) SDO images with spots on the visible solar disk.
Region 11841 [S03W50] decayed slowly and quietly.
Region 11843 [N01W36] decayed slowly and quietly.
Region 11845 [S18E24] was quiet and stable.
Region 11846 [S17E36] was mostly unchanged and
quiet.
Region 11849 [N20E17] developed significantly and could produce C flares.
Region 11850 [N07E66] produced 4 C flares and decayed slowly during the
latter half of the day.
Spotted regions not numbered by SWPC:
S2702 [S10W64] developed slowly and quietly.
New region S2703 [N03W50] emerged with one spot.
September 18-20: 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 coronal hole (CH587) in the northern hemisphere was in an Earth facing position on September 19-20.
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 to fair.
The geomagnetic field is expected to be quiet on September 21 and quiet to unsettled on September 22-23 due to effects from CH587.
| 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 | ||||||||||
| 11841 | 2013.09.10 2013.09.11 |
1 | 2 | 1 | S04W52 | 0010 | HRX | AXX |
 |
 |
location: S03W50 area: 0015 |
| S2684 | 2013.09.15 | S31W27 | plage | ||||||||
| 11848 | 2013.09.16 2013.09.19 |
1 | S11E23 | 0000 | AXX |
 |
spotless | ||||
| 11845 | 2013.09.16 2013.09.17 |
3 | S18E20 | 0004 | AXX |
 |
 |
||||
| 11847 | 2013.09.16 2013.09.17 |
N11E27 |
 |
plage | |||||||
| 11843 | 2013.09.16 2013.09.17 |
8 | 7 | 3 | N02W35 | 0050 | CSO | CSO |
 |
 |
|
| 11846 | 2013.09.17 | 4 | 8 | 3 | S17E36 | 0160 | CSO | CSO |
 |
 |
area: 0220 |
| S2692 | 2013.09.17 | N22W14 | plage | ||||||||
| S2693 | 2013.09.17 | N19W31 | plage | ||||||||
| S2694 | 2013.09.17 | N06W11 | plage | ||||||||
| S2695 | 2013.09.17 | S34W21 | plage | ||||||||
| S2698 | 2013.09.17 | S16W47 | plage | ||||||||
| S2699 | 2013.09.18 | S20W16 | plage | ||||||||
| 11849 | 2013.09.19 | 7 | 18 | 9 | N22E18 | 0010 | BXO | DAI |
 |
 |
area: 0090 |
| 11850 | 2013.09.19 | 6 | 7 | 5 | N09E62 | 0090 | DAO | DSO |
 |
 |
location: N07E66 |
| S2700 | 2013.09.19 | S20E11 |
 |
plage | |||||||
| S2701 | 2013.09.19 | N16W50 |
 |
plage | |||||||
| S2702 | 2013.09.19 | 3 | S10W64 | 0007 | AXX |
 |
 |
||||
| S2703 | 2013.09.20 | 1 | 1 | N03W50 | 0004 | AXX |
 |
||||
| Total spot count: | 27 | 49 | 22 | ||||||||
| Sunspot number: | 87 | 129 | 82 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 45 | 69 | 42 | (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): | 52 | 45 | 45 | 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 | 99.8 (1) | 34.6 (2A) / 51.9 (2B) / 38.4 (2C) | (57.8 projected, -0.4) | (5.96) |
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.
