The geomagnetic field was quiet to unsettled on September 18 under the influence of effects from CH689. Solar wind speed at SOHO ranged between 356 and 446 km/s.
Solar flux at 20h UTC on 2.8 GHz was 102.8 (decreasing 14.1 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 106.5. The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.6). Three hour interval K indices: 22333232 (planetary), 22344322 (Boulder).
The background x-ray flux is at the class B3 level.
At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 142) and 5 active regions using 1K resolution (SN: 90) SDO images on the visible solar disk.
Region 12415 [S19W25] decayed slowly losing spots and penumbral
area. The region simplified magnetically and AR S4765 was split off.
Region 12418 [S15E05] was quiet and stable.
Region 12419 [N12E08] gained a few spots as the main penumbra began to
fragment.
Spotted regions not numbered (or interpreted differently) by SWPC:
New region S4765 [S19W32] was split off from AR
12415 as there are currently 2 separate bipolar regions.
New region S4766 [N20E45] was observed with penumbra spots in an
old plage area.
New region S4767 [S27E34] emerged with a penumbra
spot.
C2+ flares:
| Magnitude | Peak time (UTC) | Location | AR | Recorded by | Comment |
| C2.6 (LDE) | 06:31 | S21W10 | 12415 | GOES15 | Type II+IV radio sweeps, CME C3.0 @ 06:40 UT @ SDO/EVE |
September 16-17: No obviously Earth directed CMEs were observed in
available LASCO imagery.
September 18: A CME was observed off the south pole and parts of the
southwest and southeast limbs after the C2 LDE in AR 12415. There is a minor
chance that the nortthernmost parts of the CME could reach Earth on September
21.
[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 large northern hemisphere coronal hole (CH689) was in an Earth facing position on September 9-16. A recurrent trans equatorial coronal hole (CH690) was in an Earth facing position on September 16-17. Another recurrent trans equatorial coronal hole (CH691) could rotate across the central meridian on September 21.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over 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 to unsettled on September 19-20 due to effects from CH690 and quiet on September 21. There is a slight chance of a weak CME impact on September 21, if that occurs unsettled to active conditions will be likely.
| 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.
(Click on image for 2K resolution)
Compare to the previous day's 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 overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 12415 | 2015.09.10 2015.09.11 |
19 | 19 | 9 | S19W29 | 0190 | EAC | DAO |
 |
 |
beta-gamma area: 0220 location: S19W25 |
| S4752 | 2015.09.11 | S01W29 | |||||||||
| 12418 | 2015.09.12 2015.09.13 |
5 | 19 | 12 | S14E05 | 0230 | CHO | CHO |
 |
 |
area: 0330 location: S15E05 |
| 12419 | 2015.09.13 2015.09.15 |
8 | 23 | 11 | N12E08 | 0070 | CAI | DAO |
 |
 |
|
| S4757 | 2015.09.14 | N03W24 | |||||||||
| S4758 | 2015.09.15 | S15E25 |
 |
merged with AR 12418 | |||||||
| S4761 | 2015.09.16 | N23E20 | |||||||||
| S4762 | 2015.09.16 | S10W59 | |||||||||
| S4763 | 2015.09.17 | S27W08 | 0003 |
 |
|||||||
| S4765 | 2015.09.18 | 17 | 7 | S19W32 | 0200 | DAO |
 |
||||
| S4766 | 2015.09.18 | 3 | N20E45 | 0008 | AXX |
 |
|||||
| S4767 | 2015.09.18 | 1 | 1 | S27E34 | 0003 | AXX |
 |
||||
| Total spot count: | 32 | 82 | 40 | ||||||||
| Sunspot number: | 62 | 142 | 90 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 52 | 107 | 65 | (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 | 78 | 77 | k * (sunspot number) As of July 1, 2015: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.85 for MSN 1K (MSN=Magnetic Sunspot Number) |
|||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) (4) |
Smoothed sunspot number (4) | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (cycle peak) | 110.5 (+1.2) | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (+2.1) (solar max) | 7.88 |
| 2014.05 | 129.7 | 132.9 | 112.5 | 115.0 (-1.4) | 5.75 |
| 2014.06 | 122.0 | 125.8 | 102.9 | 114.1 (-0.9) | 6.72 |
| 2014.07 | 137.4 | 141.8 | 100.2 | 112.6 (-1.5) | 4.50 |
| 2014.08 | 124.7 | 127.9 | 106.9 | 108.3 (-4.3) | 7.71 |
| 2014.09 | 146.6 | 148.1 | 130.0 | 101.9 (-6.4) | 9.78 |
| 2014.10 | 153.4 | 152.9 | 90.0 | 97.4 (-4.5) | 8.96 |
| 2014.11 | 154.8 | 151.4 | 103.6 | 95.0 (-2.4) | 9.33 |
| 2014.12 | 158.7 | 153.8 | 112.9 | 92.6 (-2.4) | 11.24 |
| 2015.01 | 141.9 | 137.3 | 93.0 | 89.8 (-2.8) | 9.46 |
| 2015.02 | 129.1 | 126.0 | 66.7 | 86.6 (-3.2) | 9.92 |
| 2015.03 | 125.9 | 124.6 | 54.5 | (82.1 projected, -4.5) | 16.14 |
| 2015.04 | 128.8 | 129.7 | 78.0 | (78.0 projected, -4.1) | 10.73 |
| 2015.05 | 120.0 | 122.6 | 90.0 | (75.3 projected, -2.7) | 8.29 |
| 2015.06 | 122.3 | 126.1 | 68.3 | (71.6 projected, -3.7) | 13.15 |
| 2015.07 | 107.0 | 110.8 | 66.4 | (67.9 projected, -3.7) | 8.83 |
| 2015.08 | 105.4 | 108.0 | 64.6 | (66.7 projected, -1.2) | 14.58 |
| 2015.09 | (92.5) | 31.7 (2A) / 52.8 (2B) / 69.6 (2C) | (67.0 projected, +0.3) | (18.0) | |
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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015
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 Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
