Last major update issued on March 1, 2011 at 04:45 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2105 [Dec-Jan.2011] - 2106 [Jan.-Feb.2011] NEW
The geomagnetic field was very quiet on February 28. Solar wind speed ranged between 274 and 299 km/s. The average wind density was high and it appears as if a low speed stream associated with CH437 arrived late in the day.
Solar flux measured at 20h UTC on 2.8 GHz was 95.8 (increasing 15.9 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.6). Three hour interval K indices: 00101011 (planetary), 00111121 (Boulder).
The background x-ray flux is at the class C1 level.
At midnight UTC the visible solar disk had 4 spotted regions.
Region 11163 gained a few tiny spots.
Region 11164 developed rapidly and has again become a complex region with a magnetic delta structure in a central penumbra. The background xray flux has increased quickly because of the development in this region. There's a fair chance of a major flare, even an X class flare is possible. Flares: C1.7 at 05:33, C1.1 at 06:38, C2.0 at 07:10, C2.4 at 07:38, C1.5 at 09:52, C1.2 at 12:07, M1.1 at 12:52, C1.0 at 15:52 and C1.7 at 21:31 UTC.
Region 11165 developed adding several spots.
Spotted regions not numbered by NOAA/SWPC:
[S888] This region emerged early on February 28 in the southeast quadrant. Location at midnight: S17E04
February 26-28: 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 recurrent trans equatorial coronal hole (CH437) was in an Earth facing position on February 25-26 and has since then decayed and closed. Another part (CH438) of what was a single coronal hole during the previous rotation, will be Earth facing on February 27 - March 1. CH438 is a large trans equatorial coronal hole.
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 to fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on March 1 due to weak effects from CH437, isolated active intervals are possible. Quiet to minor storm is likely on March 2-3 due to a high speed stream from CH438.
|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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with polarity overlay
|Total spot count:||24||55|
|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)|
|2009.11||73.6||4.1||7.6 (+0.5)||2.45 / 2.63|
|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||(17.1 predicted, +0.3)||8.49 / 7.77|
|2010.09||81.1||25.2||(17.7 predicted, +0.6)||5.33 / 5.45|
|2010.10||81.6||23.5||(19.0 predicted, +1.3)||6.07 / 6.27|
|2010.11||82.5||21.6||(20.7 predicted, +1.7)||4.80 / 5.50|
|2010.12||84.2||14.5||(22.2 predicted, +1.5)||3.41 / 4.35|
|2011.01||83.6||19.1||(23.8 predicted, +1.6)||4.32|
|2011.02||94.6 (1)||52.9 (2A/2B)||(25.5 predicted, +1.7)||(5.41)|
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.