Last major update issued on February 19, 2012 at 06:40 UTC.
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Annotated geomagnetic activity charts - Carrington rotation
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The geomagnetic field was quiet to unsettled on February 18. Solar wind speed ranged between 282 and 365 km/s, gradually increasing after 15h UTC as a stream from CH501 became the dominant solar wind factor. Early on February 19 the disturbance has intensified to active to minor storm conditions.
Solar flux measured at 20h UTC on 2.8 GHz was 104.1 (decreasing 36.9 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.6). Three hour interval K indices: 00001113 (planetary), 00001223 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).
Region 11417 [N20W48] reemerged with a single spot.
Region 11418 [S23W69] was quiet and stable.
Region 11419 [N28W07] added several small spots. This is a reversed polarities
region.
Region 11420 [N12W03] was quiet and stable.
New region 11421 [N18E60] rotated into view at the northeast limb on
February 17 and was numbered by SWPC the next day.
Spotted regions not reported by NOAA/SWPC:
[S1484] emerged in the southwest quadrant near the central meridian on
February 17. Location at midnight: S16W20
[S1485] emerged fairly quickly in the northeast quadrant on February 18.
Location at midnight: N16E16
[S1486] emerged in the northeast quadrant on February 18. Location at
midnight: N07E28
February 16-18: 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 trans equatorial coronal hole (CH501) was in an Earth facing position on February 15-16. A recurrent coronal hole in the southern hemisphere (CH502) will likely rotate into an Earth facing position on February 19-20.
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 fair.
The geomagnetic field is expected to be quiet to minor storm on February 19 due to effects from CH501. Quiet conditions are likely on February 20-22. A high speed stream from CH502 could arrive on February 23 and cause quiet to unsettled conditions.
| Coronal holes (1) | Coronal mass ejections (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 | ||||||||||
| 11417 | 2012.02.09 2012.02.10 |
1 | N18W52 | 0000 | AXX |
 |
location: N20W48 | ||||
| 11418 | 2012.02.10 2012.02.12 |
5 | 6 | 3 | S23W69 | 0030 | CRO | DRO |
 |
 |
|
| 11419 | 2012.02.12 | 4 | 10 | 5 | N29W05 | 0030 | CSO | CSO |
 |
 |
location: N28W07 |
| 11420 | 2012.02.12 | 1 | 3 | 3 | N11W04 | 0080 | HSX | CSO |
 |
 |
|
| S1475 | 2012.02.12 | S23W55 | plage | ||||||||
| S1477 | 2012.02.13 | S21W14 | plage | ||||||||
| S1478 | 2012.02.13 | N25W41 | plage | ||||||||
| S1479 | 2012.02.13 | N23W19 |
 |
plage | |||||||
| S1480 | 2012.02.16 | N16W32 |
 |
plage | |||||||
| 11421 | 2012.02.17 2012.02.18 |
2 | 2 | 1 | N17E59 | 0010 | AXX | HRX |
 |
 |
|
| S1482 | 2012.02.17 | N14E65 |
 |
plage | |||||||
| S1483 | 2012.02.17 | N36E10 |
 |
plage | |||||||
| S1484 | 2012.02.17 | 2 | S16W20 | 0000 | AXX |
 |
 |
||||
| S1485 | 2012.02.18 | 7 | 2 | N16E16 | 0040 | DRO |
 |
||||
| S1486 | 2012.02.18 | 1 | N07E28 | 0000 | AXX |
 |
|||||
| Total spot count: | 12 | 32 | 14 | ||||||||
| Sunspot number: | 52 | 112 | 64 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 25 | 51 | 33 | (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): | 31 | 50 | k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1, 2011) for STAR SDO 2K | ||||||||
| 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 |
3.25 |
| 2010.11 | 82.5 | 21.5 | 26.5 (+3.3) | 4.80 / 5.50 |
| 2010.12 | 84.2 | 14.4 | 28.8 (+2.3) | 3.41 / 4.35 |
| 2011.01 | 83.6 | 19.1 | 31.0 (+2.2) | 4.32 / 5.51 |
| 2011.02 | 94.6 | 29.4 | 33.4 (+2.4) | 5.41 / 6.44 |
| 2011.03 | 115.0 | 56.2 | 36.9 (+3.5) | 7.79 / 8.18 |
| 2011.04 | 112.6 | 54.4 | 41.8 (+4.9) | 9.71 / 8.83 |
| 2011.05 | 95.8 | 41.6 | 47.6 (+5.8) | 9.18 / 8.94 |
| 2011.06 | 95.8 | 37.0 | 53.2 (+5.6) | 8.96 / 8.06 |
| 2011.07 | 94.2 | 43.9 | 57.2 (+4.0) | 9.14 / 8.16 |
| 2011.08 | 101.7 | 50.6 | (60.4 projected, +3.2) | 8.16 / 7.26 |
| 2011.09 | 133.8 | 78.0 | (63.1 projected, +2.7) | 12.80 / 12.27 |
| 2011.10 | 137.3 | 88.0 | (65.8 projected, +2.7) | 7.52 / 8.28 |
| 2011.11 | 153.5 | 96.7 | (69.1 projected, +3.3) | 4.58 / 5.55 |
| 2011.12 | 141.3 | 73.0 | (73.9 projected, +4.8) | 3.32 |
| 2012.01 | 132.5 | 58.3 | (79.3 projected, +5.4) | 6.59 |
| 2012.02 | 107.1 (1) | 30.3 (2A) / 48.9 (2B) | (82.4 projected, +3.1) | (7.49) |
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 preliminary daily SWPC ap indices.
Values in red are based on the official NGDC
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.
