Last major update issued on March 18, 2011 at 05:20 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2105 [Dec-Jan.2011] - 2106 [Jan.-Feb.2011]
NEW
The geomagnetic field was quiet to unsettled on March 17. Solar wind speed ranged between 314-442 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 90.1 (decreasing 34.7 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 01000031 (planetary), 11001121 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight UTC the visible solar disk had 6 spotted regions.
Region 11172 was quiet and stable.
Region 11173 added a few spots and decayed slightly in the leading spot
section as there is only rudimentary penumbra left.
New region 11174 emerged in the northwest quadrant on March 16 and was
numbered the next day by NOAA/SWPC. The region decayed on March 17 and could
soon become spotless.
Spotted regions not numbered by NOAA/SWPC:
[S908] A single tiny spot emerged near the northern edge of CH442 on
March 17. Location a midnight: N31E27
[S909] This region emerged in the southwest quadrant on March 17.
Location at midnight: S22W23
[S910] This region emerged on March 17 near the trailing spots of region
11172. Location at midnight: N12E08
March 15-17: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since late October
2002)
Compare today's report to the situation one solar rotation ago:
28 days ago
27 days
ago 26
days ago
A small coronal hole (CH441) in the southern hemisphere will likely rotate into an Earth facing position on March 19. A coronal hole (CH442) in the northern hemisphere will likely be Earth facing on March 19-20.
The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is fair to good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be mostly quiet on March 18-21. On March 22-24 there's a chance of some unsettled intervals due to effects from CH441 and CH442.
| 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 polarity overlay |
Comment | |||
|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | STAR SDO | SWPC | STAR | Current | Previous | |||||
| 11169 | 2011.03.05 2011.03.06 |
2 | N18W89 | 0100 | HSX |
 |
rotated out of view |
|||
| 11171 | 2011.03.08 | S19W57 |
 |
plage | ||||||
| S902 | 2011.03.10 | N07W59 | plage | |||||||
| 11172 | 2011.03.10 2011.03.11 |
13 | N11W12 | 0010 | BXO |
 |
 |
location: N13W02 | ||
| S904 | 2011.03.13 | S24W30 | plage | |||||||
| 11173 | 2011.03.15 2011.03.16 |
11 | 17 | S29E26 | 0060 | CAO | CRI |
 |
 |
|
| S906 | 2011.03.16 | N21W17 |
 |
plage | ||||||
| 11174 | 2011.03.16 2011.03.17 |
2 | 1 | N22W36 | 0010 | BXO | AXX |
 |
 |
formerly region S907 |
| S908 | 2011.03.17 | 1 | N31E27 | 0000 | AXX |
 |
||||
| S909 | 2011.03.17 | 1 | S22W23 | 0000 | AXX |
 |
||||
| S910 | 2011.03.17 | 2 | N12E08 | 0000 | BXO |
 |
||||
| Total spot count: | 15 | 35 | ||||||||
| Sunspot number: | 45 | 95 | ||||||||
| 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 |
| 2009.12 | 76.7 | 10.8 | 8.3 (+0.7) | 1.41 / 1.92 |
| 2010.01 | 81.1 | 13.2 | 9.3 (+1.0) | 2.93 / 3.07 |
| 2010.02 | 84.7 | 18.8 | 10.6 (+1.3) | 4.15 / 4.61 |
| 2010.03 | 83.4 | 15.4 | 12.3 (+1.7) | 4.58 / 4.65 |
| 2010.04 | 75.9 | 8.0 | 14.0 (+1.7) | 10.22 / 10.24 |
| 2010.05 | 73.8 | 8.7 | 15.5 (+1.5) | 9.18 / 8.15 |
| 2010.06 | 72.5 | 13.6 | 16.4 (+0.9) | 8.17 / 6.85 |
| 2010.07 | 79.8 | 16.1 | 16.8 (+0.4) | 6.31 / 5.15 |
| 2010.08 | 79.2 | 19.6 | 17.4 (+0.6) | 8.49 / 7.77 |
| 2010.09 | 81.1 | 25.2 | (19.1 predicted, +1.7) | 5.33 / 5.45 |
| 2010.10 | 81.6 | 23.5 | (21.7 predicted, +2.6) | 6.07 / 6.27 |
| 2010.11 | 82.5 | 21.6 | (24.5 predicted, +2.8) | 4.80 / 5.50 |
| 2010.12 | 84.2 | 14.5 | (26.9 predicted, +2.4) | 3.41 / 4.35 |
| 2011.01 | 83.6 | 19.1 | (29.0 predicted, +2.1) | 4.32 |
| 2011.02 | 94.6 | 29.4 | (31.1 predicted, +2.1) | 5.41 |
| 2011.03 | 122.0 (1) | 47.8 (2A) / 87.1 (2B) | (33.0 predicted, +1.9) | (10.90) |
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.
