Last major update issued on February 29, 2012 at 06:20 UTC.
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Annotated geomagnetic activity charts - Carrington rotation
2118 [December 2011 - January 2012] -
2119 [January-February
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[Solar polar fields vs solar cycles - updated
June 27, 2011]
The geomagnetic field was quiet to minor storm on February 28. Solar wind speed ranged between 357 and 477 km/s. What may have been a transient was observed as a sudden increase in wind density at 06:44 UTC at SOHO. The interplanetary magnetic field swung moderately southwards and caused brief minor storm conditions.
Solar flux measured at 20h UTC on 2.8 GHz was 103.3 (decreasing 14.2 over the last solar rotation). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.8). Three hour interval K indices: 11521223 (planetary), 12421322 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).
Region 11423 [N17E04] was quiet and stable.
Region 11425 [N19W10] decayed slowly and quietly.
Region 11426 [N11W15] was quiet and stable.
Spotted regions not reported by NOAA/SWPC:
[S1496] emerged in the northeast quadrant on February 27. Location at
midnight: N12E26
[S1497] emerged in the northeast quadrant on February 27. Location at
midnight: N07W03
[S1498] emerged in the northeast quadrant on February 28. Location at
midnight: N33E31
[S1499] emerged in the southwest quadrant on February 28. Location at
midnight: S18W25
February 26-28: 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 recurrent coronal hole (CH503) in the northern hemisphere was in an Earth facing position on February 26-27. A coronal hole (CH505) in the southern hemisphere will likely rotate into an Earth facing position on Feb.29-March 1.
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 to fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on February 29. A high speed stream from CH503 could cause quiet to unsettled conditions on March 1-2.
| 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 | ||||||||||
| S1489 | 2012.02.22 | S15W40 |
 |
plage | |||||||
| S1490 | 2012.02.22 | S20W28 | plage | ||||||||
| 11423 | 2012.02.22 2012.02.23 |
1 | 3 | 3 | N17E03 | 0110 | HSX | CSO |
 |
 |
location: N17E04 area: 0200 |
| 11425 | 2012.02.23 2012.02.26 |
1 | 4 | 1 | N18W17 | 0010 | AXX | BXO |
 |
 |
location: N19W10 |
| 11424 | 2012.02.24 | N07E13 |
 |
plage | |||||||
| S1494 | 2012.02.24 | N15E18 |
 |
plage | |||||||
| S1495 | 2012.02.25 | S20W12 | plage | ||||||||
| 11426 | 2012.02.26 | 3 | 5 | 3 | N11W15 | 0010 | BXO | CRO |
 |
 |
|
| S1496 | 2012.02.27 | 9 | 4 | N12E26 | 0010 | BXO |
 |
 |
|||
| S1497 | 2012.02.27 | 2 | 1 | N07E04 | 0000 | AXX |
 |
 |
|||
| S1498 | 2012.02.28 | 2 | N33E31 | 0000 | BXO |
 |
|||||
| S1499 | 2012.02.28 | 1 | S18W25 | 0000 | AXX |
 |
|||||
| Total spot count: | 5 | 26 | 12 | ||||||||
| Sunspot number: | 35 | 96 | 62 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted penumbral SN: | 10 | 34 | 20 | (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): | 21 | 43 | 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 | 106.7 (1) | 47.3 (2A) / 49.0 (2B) | (82.4 projected, +3.1) | (8.22) |
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.
