The geomagnetic field was very quiet on May 22. Solar wind speed at SOHO ranged between 314 and 451 km/s.
Solar flux at 20h UTC on 2.8 GHz was 99.1 (decreasing 26.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 127.4. The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.8). Three hour interval K indices: 10001000 (planetary), 11012211 (Boulder).
The background x-ray flux is at the class B2 level.
At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 185) and 7 active regions using 1K resolution (SN: 109) SDO images on the visible solar disk.
Region 12348 [S10W44] decayed slowly and quietly.
Region 12349 [S20W22] developed slowly and produced the only C flare of
the day.
Region 12351 [N22E09] decayed slowly and quietly.
New region 12352 [N05E11] emerged on May 20 and was numbered by SWPC two
days later.
New region 12353 [N08W04] emerged on May 21 and received its NOAA number
the following day.
Spotted regions not numbered (or interpreted
differently) by SWPC:
S4478 [N13W29] was quiet and stable.
S4486 [N16E22] reemerged with penumbra spots.
New region S4491 [N08E02] emerged with penumbra spots.
New region S4492 [S21W02] emerged with a penumbra
spot.
New region S4493 [S10E50] emerged with a penumbra spot.
New region S4494 [N17W03] emerged with a penumbra spot.
| Magnitude | Peak time (UTC) | Location | AR | Recorded by | Comment |
| C2.0 | 23:51 | 12349 | GOES14 |
May 20: No obviously
Earth directed CMEs were observed.
May 21-22: A partial halo CME was observed late on May 21 and early on May
22. It is not yet clear if the CME source was backsided or on the visible disk.
A filament eruption in the central northern hemisphere starting near 20h UT may
have been the source, in that case the CME could have 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 southern hemisphere coronal hole (CH669) will likely rotate into an Earth facing position on May 23-25, while a northern hemisphere coronal hole (CH670) will rotate across the central meridian on May 24-26.
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.
The geomagnetic field is expected to be quiet on May 23-24. Late on May 24 and on May 25 there is a chance of a CME arrival if the CME observed on May 21/22 was caused by an observed filament eruption.
| 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 | ||||||||||
| 12346 | 2015.05.10 2015.05.11 |
2 | S05W82 | 0010 | BXO |
 |
|
||||
| 12348 | 2015.05.12 2015.05.14 |
1 | 4 | 4 | S11W45 | 0050 | HSX | CSO |
 |
 |
|
| S4467 | 2015.05.12 | N23W56 | |||||||||
| S4474 | 2015.05.16 | S09W57 | |||||||||
| 12349 | 2015.05.17 2015.05.18 |
5 | 21 | 10 | S21W20 | 0020 | BXO | CRI |
 |
 |
location: S20W22 area: 0045 |
| 12350 | 2015.05.17 2015.05.18 |
S15W35 |
 |
||||||||
| 12351 | 2015.05.17 2015.05.19 |
1 | 4 | N22E05 | 0010 | AXX | BXO |
 |
 |
||
| S4478 | 2015.05.17 | 5 | 2 | N13W29 | 0014 | AXX |
 |
 |
|||
| 12352 | 2015.05.20 2015.05.22 |
8 | 11 | 9 | N05E10 | 0030 | BXI | DRI |
 |
 |
beta-gamma |
| S4485 | 2015.05.20 | S08E32 | |||||||||
| S4486 | 2015.05.20 | 6 | N16E22 | 0010 | AXX |
 |
|||||
| 12353 | 2015.05.21 2015.05.22 |
4 | 18 | 12 | N07W03 | 0040 | CRO | DAI |
 |
 |
|
| S4489 | 2015.05.21 | N19E32 |
 |
||||||||
| S4490 | 2015.05.21 | S11W03 |
 |
||||||||
| S4491 | 2015.05.22 | 3 | 1 | N08E02 | 0009 | BXO |
 |
||||
| S4492 | 2015.05.22 | 1 | 1 | S21W02 | 0015 | HRX |
 |
||||
| S4493 | 2015.05.22 | 1 | S10E50 | 0002 | AXX |
 |
|||||
| S4494 | 2015.05.22 | 1 | N17W03 | 0002 | AXX |
 |
|||||
| Total spot count: | 21 | 75 | 39 | ||||||||
| Sunspot number: | 81 | 185 | 109 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 29 | 94 | 58 | (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): | 49 | 65 | 60 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number) | |||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2013.12 | 147.7 | 143.1 | 90.3 | 76.0 (+0.6) | 4.68 |
| 2014.01 | 157.4 | 152.4 | 81.8 | 77.3 (+1.3) | 5.44 |
| 2014.02 | 170.3 (cycle peak) |
166.3 | 102.3 (cycle peak) | 78.4 (+1.1) | 10.70 |
| 2014.03 | 149.9 | 148.5 | 91.9 | 80.8 (+2.4) | 4.88 |
| 2014.04 | 143.9 | 144.8 | 84.7 | 81.9 (+1.1) (solar max) | 7.88 |
| 2014.05 | 129.7 | 132.9 | 75.2 | 80.5 (-1.4) | 5.75 |
| 2014.06 | 122.0 | 125.8 | 71.0 | 79.7 (-0.8) | 6.72 |
| 2014.07 | 137.4 | 141.8 | 72.5 | 78.5 (-1.2) | 4.50 |
| 2014.08 | 124.7 | 127.9 | 74.7 | 75.5 (-3.0) | 7.71 |
| 2014.09 | 146.6 | 148.1 | 87.6 | 70.8 (-4.7) | 9.78 |
| 2014.10 | 153.4 | 152.9 | 60.6 | 67.3 (-3.5) | 8.96 |
| 2014.11 | 154.8 | 151.4 | 70.1 | (64.9 projected, -2.4) | 9.33 |
| 2014.12 | 158.7 | 153.8 | 78.0 | (62.6 projected, -2.3) | 11.24 |
| 2015.01 | 141.9 | 137.3 | 67.0 | (60.4 projected, -2.2) | 9.46 |
| 2015.02 | 129.1 | 126.0 | 44.8 | (58.7 projected, -1.7) | 9.92 |
| 2015.03 | 125.9 | 124.6 | 38.4 | (56.3 projected, -2.4) | 16.14 |
| 2015.04 | 128.8 | 129.7 | 54.4 | (53.7 projected, -2.6) | 10.73 |
| 2015.05 | (130.1) | 70.6 (2A) / 99.5 (2B) / 78.2 (2C) | (51.5 projected, -2.2) | (9.2) | |
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 WDC-SILSO
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
GFZ 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.
