|Charts (* = updated daily||Data and archive|
|Solar wind (*)||Solar and geomagnetic data - last month (*)|
|Electron fluence (*)||Archived daily reports and monthly data from 2003.01 (April 2, 2016)|
|Solar cycle||Solar cycles 23-24 (April 2, 2016)||Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)|
|Cycle 24 progress (April 2, 2016)||Noon SDO sunspot count 1K / 4K (*)|
|Solar cycles 1-24 (July 17, 2015)||POES auroral activity level October 2009 - December 2012|
|Comparison of cycles 21, 22, 23 and 24 (April 2, 2016)||3rd SSN Workshop, Tucson, 2013|
|Comparison of cycles 12, 13, 14, 16 and 24 (April 2, 2016)||4th SSN Workshop, Locarno, 2014|
|Solar polar fields vs. solar cycles (April 20, 2016)|
The geomagnetic field was quiet on April 28. Solar wind speed at SOHO ranged between 368 and 459 km/s.
Solar flux at 20h UTC on 2.8 GHz was 94.9 (increasing 12.8 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 95.2. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 21111000 (planetary), 21222321 (Boulder).
The background x-ray flux is at the class B2 level.
At the time of counting spots (see image time), spots were observed in 9 active regions using 2K resolution (SN: 141) and 7 active regions using 1K resolution (SN: 99) SDO images on the visible solar disk.
Region 12533 [S02W35] was quiet and stable.
Region 12535 [N07E16] produced several low level C flares.
Region 12536 [N17E29] was mostly unchanged and could produce C flares.
Region 12537 [S08W66] lost a few spots and is capable of C class flaring.
Region 12538 [S04E22] was quiet and stable.
New region 12539 [N17E68] rotated into view on April 27 and was numbered the next day by SWPC.
Spotted regions not numbered (or interpreted differently) by SWPC:
S5258 [S17E10] reemerged with tiny spots.
New region S5260 [N06W37] emerged with tiny spots.
New region S5261 [S10W39] emerged with a tiny spot.
|Magnitude||Peak time (UT)||Location||AR||Recorded by||Comment|
April 26-27: No obviously Earth directed CMEs were observed in available
April 28: A partial halo CME was observed after a filament eruption in the northeast quadrant after 07h UT. There is a chance components of this CME could reach Earth on May 1.
history (since October 2002)]
[Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago]
A recurrent northern hemisphere coronal hole (CH730) rotated across the central meridian on April 27-28 while a southern hemisphere coronal hole (CH731) was in an Earth facing position on April 26-27.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet most of April 29 becoming quiet to active from late in the day until May 1 due to effects from CH730 and CH731.
|Coronal holes (1)||Coronal mass ejection (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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution). 4K resolution. Compare to the previous day's image. 0.5K image
|Active region||Date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlays
|Total spot count:||24||51||29|
|Sunspot number:||84||141||99||(total spot count + 10 * number of spotted regions)|
|Relative sunspot number (Wolf number):||92||63||79||k * (sunspot number)
As of February 19, 2016: k = 1.1 for SWPC, k = 0.45 for MSN 2K, k = 0.80 for MSN 1K (MSN=Magnetic Sunspot Number)
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number (4)||Average
|166.3||146.1 (cycle peak)||110.5 (+1.2)||10.70|
|2014.04||143.9||144.8||112.5||116.4 (+2.1) (solar max)||7.88|
|2015.10||104.1||103.3||61.7||(64.6 projected, -1.4)||14.02|
|2015.11||109.3||106.9||63.2||(61.9 projected, -2.7)||12.09|
|2015.12||113.1||109.5||57.7||(59.9 projected, -2.0)||14.29|
|2016.01||103.4||100.1||56.6||(58.2 projected, -1.7)||9.4|
|2016.02||103.6||101.0||57.2||(55.9 projected, -2.3)||9.9|
|2016.03||91.5||90.6||54.9||(52.9 projected, -3.0)||10.58|
|2016.04||(93.3)||33.4 (2A) / 35.8 (2B) / 41.1 (2C)||(50.2 projected, -2.7)||(9.1)|
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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015
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 Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.