Last major update issued on April 16, 2014 at 04:55 UTC.
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The geomagnetic field was quiet on April 15. Solar wind speed at SOHO ranged between 336 and 373 km/s.
Solar flux at 20h UTC on 2.8 GHz was 161.9 (increasing 12.7 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 151.3. The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.1). Three hour interval K indices: 12111111 (planetary), 22212212 (Boulder).
The background x-ray flux is at the class B9 level.
At the time of counting spots (see image time), spots were observed in 12 active regions in 2K resolution (SN: 310) and 12 active regions in 1K resolution (SN: 243) SDO images on the visible solar disk.
Region 12032 [N11W28] was quiet and stable.
Region 12033 [N11W17] was quiet and stable.
Region 12034 [N04W00] was quiet and stable.
Region 12035 [S16E24] developed slowly and is displaying increased polarity intermixing. A minor M class flare is possible. C5+ flares: C8.6 at 09:15, C7.3 at 17:59 UTC.
Region 12036 [S18W00] developed further. While there is a magnetic delta structure in the central southern section, opposite polarity umbrae are not very close. Still, there is a chance of a major flare.
Region 12037 [S10E01] developed significantly, particularly in the leading spot section. The region has small magnetic delta structures and could produce an M class flare.
New region 12038 [S13E65] rotated into view on April 14 with SWPC numbering the region the next day.
New region 12039 [N14E25] was first observed with spots on April 13. The region developed on April 15 and was numbered by SWPC.
New region 12040 [N23E11] emerged with a few spots.
Spotted regions not numbered (or interpreted differently) by SWPC:
S3322 [S03W75] was quiet and stable.
S3323 [S15E42] was quiet and stable.
New region S3328 [S21W16] emerged with a few spots.
April 13-15: 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 small coronal hole (CH612) in the southern hemisphere with a possible trans equatorial extension will rotate across the central meridian on April 16.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet on April 16-18. Weak effects from CH612 could cause unsettled intervals on April 19.
|Coronal holes (1)||Coronal mass ejection (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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution) Compare to the previous day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue 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:||59||190||123|
|Sunspot number:||149||310||243||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||99||239||172||(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):||89||109||134||k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number||Average ap
|2013.10||132.1||131.2||85.6||(74.9 projected, +1.8)||7.71|
|2013.11||148.3||145.1||77.6||(74.9 projected, -0.0)||5.68|
|2013.12||147.7||143.1||90.3||(74.4 projected, -0.5)||4.68|
|2014.01||157.4||152.4||82.0||(74.3 projected, -0.1)||5.44|
|166.3||102.8 (cycle peak)||(73.7 projected, -0.6)||10.70|
|2014.03||149.9||148.5||92.2||(73.8 projected, +0.1)||4.88|
|2014.04||144.2 (1)||57.5 (2A) / 114.9 (2B) / 105.7 (2C)||(73.0 projected, -0.8)||(6.9)|
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 WDC-SILSO international sunspot number is typically 30-50% lower. 2B) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international GFZ Potsdam WDC ap indices.
This report has been prepared by Jan Alvestad. It is based on the 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.