The geomagnetic field was unsettled to active on August 26. Solar wind speed at SOHO ranged between 350 and 424 km/s. A disturbance (source unknown) was observed beginning at SOHO near 08:15 UT. For the remainder of the day the solar wind was low speed, high density and fairly cold while the interplanetary magnetic field slowly became stronger with an increasingly more southward Bz. Early on August 27 minor to major geomagnetic storming is being observed.
Solar flux at 20h UTC on 2.8 GHz was 126.2 (increasing 24.2 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 114.9. The Potsdam WDC planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 25.1). Three hour interval K indices: 33344444 (planetary), 33355333 (Boulder).
The background x-ray flux is at the class B6 level.
At the time of counting spots (see image time), spots were observed in 5 active regions using 2K resolution (SN: 121) and 3 active regions using 1K resolution (SN: 67) SDO images on the visible solar disk.
Region 12403 [S15W43] decayed slowly in the
trailing spot section with penumbral fragmentation observed and the loss of a
magnetic delta. The leading spot section has two magnetic deltas and there is a
fair chance of an M class event before the region rotates out of view. losing
penumbral area and spots.
Region 12404 [N14W58] decayed slowly and quietly.
Spotted regions not numbered (or interpreted differently) by SWPC:
S4703 [N16E22] gained more trailing polarity penumbra spots and was quiet.
S4712 [S13W20] was quiet and stable.
New region S4713 [S21E62] was observed with
penumbra spots.
C2+ flares:
| Magnitude | Peak time (UTC) | Location | AR | Recorded by | Comment |
| C9.5/2N (LDE) | 13:53 | S11W41 | 12403 | GOES15 | |
| C5.0 | 15:07 | 12403 | GOES15 | ||
| C2.6 | 19:11 | 12403 | SDO/EVE | triggered extensive filament eruption to the north of AR 12403 | |
| C2.8 | 19:43 | SDO/EVE | |||
| C2.3 | 00:08 (Aug.27, began at 23:51) | GOES15 | source probably 12403, simultaneous activity in AR S4713 |
August 24-25: No obviously Earth directed CMEs were observed.
August 26: A CME was observed off the west limb from 20:36 UT in LASCO C2
imagery. This was likely associated with an extensive filament eruption to the
north and northeast of AR 12403. Further LASCO imagery will be required to
determine if the CME has any Earth directed components.
[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 trans equatorial coronal hole (CH685) was in an Earth facing position on August 25-26.
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 fair to good.
The geomagnetic field is expected to be unsettled to major storm on August 27. A high speed stream associated with CH685 could become geoeffective late on August 27 and may cause quiet to active conditions on August 28-29.
| 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 | ||||||||||
| 12403 | 2015.08.17 2015.08.18 |
35 | 53 | 31 | S16W44 | 1100 | FKC | FKC |
 |
 |
beta-gamma-delta area: 0850 |
| 12404 | 2015.08.19 2015.08.20 |
1 | N14W60 | 0001 | AXX |
 |
 |
||||
| S4703 | 2015.08.22 | 14 | 5 | N16E22 | 0030 | BXO | images/AR_S4703_20150826_2345.png |
 |
|||
| S4704 | 2015.08.22 | S23W30 | |||||||||
| S4706 | 2015.08.23 | S15W09 | |||||||||
| S4707 | 2015.08.23 | S12W55 | |||||||||
| S4709 | 2015.08.24 | N22W43 | |||||||||
| S4710 | 2015.08.25 | N05W45 |
 |
||||||||
| S4711 | 2015.08.25 | S02W28 |
 |
||||||||
| S4712 | 2015.08.25 | 1 | S13W20 | 0001 | AXX |
 |
 |
||||
| S4713 | 2015.08.26 | 2 | 1 | S21E62 | 0006 | AXX |
 |
||||
| Total spot count: | 35 | 71 | 37 | ||||||||
| Sunspot number: | 45 | 121 | 67 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 45 | 81 | 47 | (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): | 50 | 67 | 57 | 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 |
| 2014.03 | 149.9 | 148.5 | 128.7 | 114.3 (+3.8) | 4.88 |
| 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 | (86.8 projected, -3.0) | 9.92 |
| 2015.03 | 125.9 | 124.6 | 54.5 | (83.1 projected, -3.7) | 16.14 |
| 2015.04 | 128.8 | 129.7 | 78.0 | (79.8 projected, -3.3) | 10.73 |
| 2015.05 | 120.0 | 122.6 | 90.0 | (77.4 projected, -2.4) | 8.29 |
| 2015.06 | 122.3 | 126.1 | 68.3 | (73.9 projected, -3.5) | 13.15 |
| 2015.07 | 107.0 | 110.8 | 66.4 | (70.2 projected, -3.7) | 8.83 |
| 2015.08 | (106.6) | 53.5 (2A) / 63.8 (2B) / 78.2 (2C) | (69.0 projected, -1.2) | (12.4) | |
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).
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.
