|Charts (* = updated daily)||Data and archive|
|Solar wind (*)||Solar and geomagnetic data - last month (*)|
|Electron fluence (*)||Archived daily reports and monthly data since 2003.01 (March 1, 2022)|
|Solar cycle||Solar cycles 23-25 (March 1, 2022)||Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)|
|Cycle 24-25 progress (March 1, 2022)||Noon SDO sunspot count 1K image / 4K (*)|
|Solar cycles 1-24 (June 1, 2020)||POES auroral activity level October 2009 - December 2012]|
|Comparison of cycles 21-25 (March 1, 2022)||3rd SSN Workshop, Tucson, 2013|
|Comparison of cycles 12-14, 16, 24-25 (March 1, 2022)||4th SSN Workshop, Locarno, 2014|
|Solar polar fields vs. solar cycles (April 10, 2022)||Cycle 25 spots (final update December 25, 2019)|
|Solar cycles 24-25 transition using 365d smoothing||Research: Solar Cycle 25 Started on November 17, 2019 with 365 Days Smoothing|
The geomagnetic field was quiet to active on April 23, late in the day under the influence of effects from CH1075. The high latitude magnetometer at Andenes recorded quiet to major storm levels.
Solar flux density measured at 20h UT on 2.8 GHz was 160 - increasing 29.7 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 93.44). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.0). Three hour interval K indices: 22133234 (planetary), 22243323 (Boulder), 43143365 (Andenes).
The background x-ray flux is at the class B7 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 10 active regions using 2K resolution (SN: 237) and in 9 active regions using 1K resolution (SN: 154) SDO/HMI images.
Region 12991 [S22W49] decayed slowly and
Region 12993 [N20W18] decayed slowly producing small C flares. There's a weak magnetic delta structure in a penumbra to the north of the main penumbrae. C1 flares: C1.1 @ 02:40, C1.9 @ 06:04, C1.2 @ 08:04, C1.1 @ 09:52, C1.2 @ 20:53, C1.4 @ 21:49, C1.2 @ 23:12, C1.5 @ 23:54 UT
Region 12994 [N14W11] was mostly unchanged and produced some low level C flares. C1 flares: C1.5 @ 07:07, C1.3 @ 16:13 UT.
Region 12995 [N14E17] decayed slowly and quietly.
Region 12996 [N25E29] was quiet and stable.
New region 12997 [N12E64] rotated into view on April 22 and was numbered the next day by SWPC.
New region 12998 [S20E77] rotated into view early in the day.
Spotted regions not observed (or interpreted
differently) by SWPC:
S7505 [S15W29] decayed slowly and quietly.
S7510 [N27E48] decayed slowly and quietly.
S7515 [S18E27] was quiet and stable.
|Magnitude||Peak time (UT)||Location||Source||Recorded by||Comment|
April 22-23: No obviously Earth directed CMEs
were observed in available LASCO imagery.
April 21: The CME observed after the M9.6 flare in AR 12993 early in the day had a narrow core. LASCO imagery is not conclusive with regards to faint, slow moving components of the CME in other directions than towards the northeast. If there is any impact from this CME it will likely not be very significant.
[Coronal hole 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 northern hemisphere coronal hole (CH1075) rotated across the central meridian on April 20-21. A recurrent southern hemisphere coronal hole (CH1076) will likely be Earth facing on April 26-27.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
Quiet to active conditions are likely on April 24-25 due to effects from CH1075 becoming quiet on April 26-27.
|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 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: 0-30% 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
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. 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. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
|Active region||SWPC date numbered
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with magnetic polarity overlays
was AR S7516
SWPC location way off
|Total spot count:||48||137||64|
|Sunspot number:||118||237||154||(total spot count + 10 * number of spotted regions)|
|Weighted SN:||88||175||102||(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):||130||130||123|
|Month||Average solar flux||International sunspot number
|Smoothed sunspot number (4)||Average ap
|166.3||146.1 (SC24 peak)||110.5||10.70|
|2014.04||143.9||144.8||112.5||116.4 (solar max)||7.88|
(Solar minimum using 365d smoothing:
November 17, 2019)
(ISN 13 months smoothed
|2021.10||88.9||88.3||38.1||(44.9 projected, +4.9)||7.38|
|2021.11||86.2||84.4||35.0||(50.5 projected, +5.6)||9.83|
|2021.12||103.0||99.8||67.6||(56.4 projected, +5.9)||6.40|
|2022.01||103.8||100.5||54.0||(60.0 projected, +3.6)||8.92|
|2022.02||109.1||106.5||59.7||(64.8 projected, +4.8)||10.46|
|2022.03||117.0||115.8||78.3||(70.2 projected, +5.4)||10.20|
|2022.04||126.5 (1)||53.3 (2A) / 69.5 (2B) / 94.7 (2C)||(75.4 projected, +5.2)||(12.5)|
|2022.05||(81.8 projected, +6.4)|
|2022.06||(87.7 projected, +5.9)|
|2022.07||(94.9 projected, +7.2)|
|2022.08||(101.6 projected, +6.7)|
|2022.09||(106.6 projected, +5.0)|
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
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) Source: SIDC-SILSO.
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.