Last major update issued on June 1, 2012 at 05:15 UTC.
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[Graphical comparison of cycles 10, 12, 13, 14, 16 and
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(last update April 5, 2007)]
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[POES auroral activity level since October
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[Solar polar fields vs solar cycles - updated
June 27, 2011]
The geomagnetic field was quiet to active on May 31. Solar wind speed at SOHO ranged between 346 and 451 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 117.3 (increasing 3.3 over the last solar rotation). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 9.9). Three hour interval K indices: 32222241 (planetary), 32332321 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).
Region 11490 [S13W37] decayed slowly and quietly.
Region 11492 [S13W08] decayed further with a significant reduction in
penumbral area.
New region 11493 [N13E64] rotated into view at the northeast limb on May
30 and was numbered by SWPC the next day. Further C class flaring is likely.
New region 11494 [S17E73] rotated into view at the southeast limb on May
30 and was assignned a number by SWPC the following day.
New region 11495 [S15E19] emerged on May 27 and developed on May 31 with
minor polarity intermixing.
Spotted active regions not numbered by NOAA/SWPC:
S1693 [S21E07] reemerged with a single spot.
S1699 [N15E73] rotated fully into view.
S1700 [S22E48] decayed slowly and quietly.
New region S1701 [N07E84] rotated into view.
New region S1702 [S27E07] emerged with a tiny spot.
May 29-31: No obviously Earth directed CMEs were observed in LASCO or 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 large recurrent trans equatorial coronal hole (CH520) will likely rotate into an Earth facing position on June 2-4.
The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using this method, the extent and intensity of both CHs are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on June 1 and quiet on June 2-4. Unsettled to minor storm conditions are likely on June 5-6 due to effects from CH520.
| 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 higher resolution image) 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 (blue-green) 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 | ||||||||||
| 11489 | 2012.05.21 2012.05.22 |
S30W72 |
|
||||||||
| 11488 | 2012.05.21 2012.05.22 |
N12W73 | plage | ||||||||
| 11490 | 2012.05.23 2012.05.24 |
6 | 9 | 5 | S13W36 | 0110 | DSO | DSO |
 |
 |
beta-gamma |
| 11492 | 2012.05.24 2012.05.25 |
9 | 16 | 11 | S13W11 | 0100 | ESO | DSO |
 |
 |
location: S13W08 |
| S1682 | 2012.05.25 | S25W03 |
 |
plage | |||||||
| S1683 | 2012.05.25 | N01W48 | plage | ||||||||
| S1684 | 2012.05.25 | N21W59 | plage | ||||||||
| S1686 | 2012.05.26 | S18W53 | plage | ||||||||
| S1687 | 2012.05.26 | S28W47 | plage | ||||||||
| S1690 | 2012.05.26 | S07W18 | plage | ||||||||
| S1691 | 2012.05.26 | S26W25 | plage | ||||||||
| 11495 | 2012.05.27 2012.05.31 |
5 | 16 | 8 | S12E19 | 0030 | CRO | DRI |
 |
 |
beta-gamma location: S15E19 |
| S1693 | 2012.05.28 | 1 | 1 | S21E07 | 0000 | AXX |
 |
||||
| S1694 | 2012.05.28 | N09W07 | plage | ||||||||
| S1696 | 2012.05.29 | S27W45 | plage | ||||||||
| 11494 | 2012.05.30 2012.05.31 |
1 | 2 | 2 | S16E69 | 0050 | HSX | CAO |
 |
 |
area: 0160 location: S17E73 |
| 11493 | 2012.05.30 2012.05.31 |
2 | 11 | 5 | N15E64 | 0040 | DSO | DAI |
 |
 |
area: 0140 location: N13E64 |
| S1699 | 2012.05.30 | 4 | 4 | N15E73 | 0200 | CAO |
 |
 |
|||
| S1700 | 2012.05.30 | 12 | 4 | S22E48 | 0050 | DRI |
 |
 |
|||
| S1701 | 2012.05.31 | 2 | 1 | N07E84 | 0080 | CSO |
 |
||||
| S1702 | 2012.05.31 | 1 | 1 | S27E07 | 0000 | AXX |
 |
||||
| Total spot count: | 23 | 74 | 42 | ||||||||
| Sunspot number: | 73 | 174 | 142 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 46 | 110 | 78 | (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): | 44 | 61 | 78 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) 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) |
|---|---|---|---|---|
| 2008.07 | 65.7 (SF minimum) | 0.5 | 2.8 (-0.4) | |
| 2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
|
| 2011.02 | 94.6 | 29.4 | 33.4 (+2.4) | 6.44 |
| 2011.03 | 115.0 | 56.2 | 36.9 (+3.5) | 8.18 |
| 2011.04 | 112.6 | 54.4 | 41.8 (+4.9) | 8.83 |
| 2011.05 | 95.8 | 41.6 | 47.6 (+5.8) | 8.94 |
| 2011.06 | 95.8 | 37.0 | 53.2 (+5.6) | 8.06 |
| 2011.07 | 94.2 | 43.9 | 57.2 (+4.0) | 8.16 |
| 2011.08 | 101.7 | 50.6 | 59.0 (+1.8) | 7.26 |
| 2011.09 | 133.8 | 78.0 | 59.5 (+0.5) | 12.27 |
| 2011.10 | 137.3 | 88.0 | 59.9 (+0.4) | 8.28 |
| 2011.11 | 153.5 | 96.7 | (61.2 projected, +1.3) | 5.55 |
| 2011.12 | 141.3 | 73.0 | (63.9 projected, +2.7) | 3.78 |
| 2012.01 | 132.5 | 58.3 | (67.4 projected, +3.5) | 7.15 |
| 2012.02 | 106.5 | 33.1 | (71.4 projected, +4.0) | 8.81 |
| 2012.03 | 114.7 | 64.2 | (73.5 projected, +2.1) | 16.08 |
| 2012.04 | 113.0 | 55.2 | (74.5 projected, +1.0) | 10.10 |
| 2012.05 | 121.5 (1) | 99.1 (2A / 2B) | (75.8 projected, +1.3) | (8.75) |
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) Month
average to date.
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 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.
