Last major update issued on April 15, 2011 at 05:35 UTC. Minor update posted at 16:20 UTC
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Annotated geomagnetic activity charts - Carrington rotation 2106 [Jan.-Feb.2011] - 2107 [Feb.-March 2011]
The geomagnetic field was quiet to unsettled on April 14. Solar wind speed ranged between 390 and 512 km/s under the decreasing influence of a high speed stream.
Solar flux measured at 20h UTC on 2.8 GHz was 118.7 (increasing 31.1 over the last solar rotation). The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.1). Three hour interval K indices: 12211313 (planetary), 12211103 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 9 spotted regions.
Region 11186 decayed slowly and quietly.
Region 11189 decayed slowly and quietly. [Note that SWPC currently has this region as 11185 with the real region 11185 having been renumbered 11189]
Region 11190 developed quickly with large penumbrae forming. The leading penumbra is very interesting as an opposite polarity spot has emerged near the center forming a magnetic delta structure. The intermediate penumbra has a magnetic delta as well. M flares are likely
Region 11191 was quiet and stable.
Region 11192 decayed slowly and quietly.
Region 11193 is a complex and compact region with a magnetic delta structure at the southeastern edge of the leading penumbra. M flares are possible.
New region 11194 reemerged in the southwest quadrant on April 13 and was numbered the next day by NOAA/SWPC.
Spotted regions not numbered by NOAA/SWPC:
[S952] emerged in the southern hemisphere near the central meridian on April 14. Location at midnight: S20W01
[S953] emerged in the northeast quadrant on April 14. Location at midnight: N20E27.
A filament eruption in the southeast quadrant (traces captured on the AIA 193 image below) late in the day may be interesting (awaiting further analysis).
Comment added at 16:20 UTC on April 15: Region 11190 has seen most of the leading and intermediate penumbrae merge into a very complex, huge penumbra measuring 6 degrees longitudinally and 3.5 degrees latitudinally. Opposite polarity umbrae inside this penumbra are very close to each other and there's a long neutral line. A major flare is possible. The latest high resolution STAR CHARMAP shows regions S951 and 11187 reemerging with spots. An extension of the southern polar coronal hole will likely rotate into an Earth facing position on April 16.
April 12-14: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since late October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
No obvious coronal holes are currently in or near Earth facing positions.
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 poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be mostly quiet on April 15-17.
|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
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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with polarity overlay
|2||0020||HRX||SWPC data is for region 11189
|2||4||S32W42||0010||BXO||BXO||formerly region S944|
|Total spot count:||61||132|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|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||16.7 (+0.3)||6.31 / 5.15|
|2010.08||79.2||19.6||17.4 (+0.7)||8.49 / 7.77|
|2010.09||81.1||25.2||19.6 (+2.2)||5.33 / 5.45|
|2010.10||81.6||23.5||(22.6 predicted, +3.0)||6.07 / 6.27|
|2010.11||82.5||21.5||(25.7 predicted, +3.1)||4.80 / 5.50|
|2010.12||84.2||14.4||(28.9 predicted, +3.2)||3.41 / 4.35|
|2011.01||83.6||19.1||(31.9 predicted, +3.0)||4.32 / 5.51|
|2011.02||94.6||29.4||(34.4 predicted, +2.5)||5.41 / 6.44|
|2011.03||115.0||56.2||(36.7 predicted, +2.3)||7.79|
|2011.04||110.9 (1)||39,5 (2A) / 84.6 (2B)||(39.6 predicted, +2.9)||(12.29)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.