Last major update issued on March 27, 2011 at 06:05 UTC. Minor update posted at 11:20 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2106 [Jan.-Feb.2011] - 2107 [Feb.-March 2011] NEW
The geomagnetic field was very quiet on March 26. Solar wind speed ranged between 350-431 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 114.5 (increasing 24.1 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 00012111 (planetary), 00112211 (Boulder).
The background x-ray flux is at the class B5 level. A long duration C2 (estimated) event peaked in the morning during a GOES-15 data dropout. This event was associated with a large CME from a source behind the east limb.
At midnight UTC the visible solar disk had 7 spotted regions.
Region 11176 added quite a few tiny spots in the large trailing
polarity area. At midnight the westernmost spot was at E07 while the easternmost
spot was at E37. It is rare that a region spans 30 degrees longitudinally.
There's a weak magnetic delta structure in the southern central part of the
region. M class flaring is likely
Flare: C1.0 at 00:58 UTC.
Region 11177 was quiet and stable.
Region 11178 developed during the first half of the day adding penumbra on both polarities, slow decay was observed later in the day.
Region 11180 added a few small trailing spots.
Region 11181 was quiet and stable.
Spotted regions not numbered by NOAA/SWPC:
[S921] became visible at the northeast limb before noon on March 26. Early on March 27 trailing spots are becoming visible and the classification is changing to EAO. Location at midnight: N15E77
[S922] tiny spots emerged late on March 26. Location at midnight: N23E24.
Minor update added at 11:20 UTC on March 27: Not much activity of interest during the first half of the day. Regions S915 and S919 have reemerged with spots while region S921 has rotated fully into view and currently has an EAI classification. Region 11176 could be splitting into two regions with the leading penumbra and some nearby opposite polarity spots becoming a new region. The latest STAR CHARMAP.
March 25-26: No obviously Earth directed CMEs were observed in LASCO
and STEREO imagery.
March 24: A small partial halo CME was observed in association with an M1 flare in region 11176.
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 fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on March 27 and 29. On March 28 there's a chance of unsettled and active intervals if the CME observed on March 24 reaches Earth.
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
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:||44||106|
|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)|
|2009.12||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||114.7 (1)||64.6 (2A) / 77.0 (2B)||(33.0 predicted, +1.9)||(8.63)|
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.