Last major update issued on March 3, 2012 at 05:05 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2118 [December 2011 - January 2012] - 2119 [January-February 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet to unsettled on March 2. Solar wind speed ranged between 359 and 461 km/s under the influence of a high speed stream from CH503. Early on March 3 another high speed stream (from CH505) has become the dominant solar wind source.
Solar flux measured at 20h UTC on 2.8 GHz was 108.2 (increasing 1.2 over the last solar rotation). The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.4). Three hour interval K indices: 33313122 (planetary), 33313222 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).
Region 11423 [N16W34] was quiet and stable.
Region 11427 [N15W15] lost some spots, however, opposite polarity spots are currently observed within the small penumbra. C flares are possible.
Spotted regions not reported by NOAA/SWPC:
[S1504] emerged in the northeast quadrant on March 1. Location at midnight: N12E03
[S1505] emerged in the southeast quadrant on March 2. Location at midnight: S27E51
[S1506] emerged in the southeast quadrant on March 2. Location at midnight: S17E67
[S1507] rotated partly into view at the northeast limb on March 2 revealing a huge penumbra with a latitudinal extent in excess of 5 degrees. The region could produce further M class flares, even an X flare is possible. Flare: M3.3 at 17:46 UTC. The flare was associated with a CME off the east limb.
[S1508] emerged in the southwest quadrant on March 2. Location at midnight: S18W18
February 29-March 2: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
Coronal hole history (since October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A coronal hole (CH505) in the southern hemisphere was in an Earth facing position on Feb.29-March 1. A recurrent, elongated coronal hole (CH506) in the southern hemisphere will likely rotate into an Earth facing position on March 3-4.
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. Propagation on long distance northeast-southwest paths is good.
The geomagnetic field is expected to be quiet to active on March 3 due to effects from CH505, becoming quiet to unsettled on March 4 and quiet on March 5. On March 6-8 a high speed stream from CH506 could cause quiet to unsettled conditions with occasional active intervals.
|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 magnetic polarity overlay
|Total spot count:||4||22||10|
|Sunspot number:||24||92||60||(total spot count + 10 * number of spotted regions)|
|Weighted penumbral SN:||12||42||30||(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):||14||32||33||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K|
|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)|
|2010.12||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||59.0 (+1.8)||8.16 / 7.26|
|2011.09||133.8||78.0||(59.2 projected, +0.2)||12.80 / 12.27|
|2011.10||137.3||88.0||(59.4 projected, +0.2)||7.52 / 8.28|
|2011.11||153.5||96.7||(60.8 projected, +1.4)||4.58 / 5.55|
|2011.12||141.3||73.0||(63.6 projected, +2.8)||3.32|
|2012.01||132.5||58.3||(67.1 projected, +3.5)||6.59|
|2012.02||106.5||33.1||(71.0 projected, +3.9)||8.09|
|2012.03||105.8 (1)||1.5 (2A) / 24.0 (2B)||(73.2 projected, +2.2)||(12.75)|
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.