The geomagnetic field was quiet to major storm on March 20 under the influence of a high speed stream associated with CH1000. The high latitude magnetometer at Andenes recorded quiet to major storm conditions.
Solar flux at 17h UT on 2.8 GHz was 75.9 - unchanged 0.0 over the previous solar rotation (the value recorded at 20h UT was too high compared to other same day measurements). (Centered 1 year average SF at 1 AU - 183 days ago: 74.52). The Potsdam WDC planetary A index was 30 (STAR Ap - based on the mean of three hour interval ap indices: 30.5). Three hour interval K indices: 23654434 (planetary), 23554324 (Boulder), 31443466 (Andenes).
The background x-ray flux is at the class A7 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 3 active regions using 2K resolution (SN: 42) and in 2 active regions using 1K resolution (SN: 24) SDO/HMI images.
Region 12810 [N19E15] decayed slowly and quietly.
Spotted regions not observed (or interpreted
differently) by SWPC:
New region S6782 [S07W37] emerged with tiny spots. This is likely a
SC24 group.
New region S6783 [N20E73] rotated into view
with tiny spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
March 18-19: No obviously Earth directed CMEs were observed in available LASCO imagery.
March 20: Several filament eruptions were observed in SDO/AIA imagery
with the first one beginning at approximately 01:17 UT in the southeast
quadrant near the central meridian. Filament eruptions followed in the
northern hemisphere. A halo CME was observed following these eruptions, the
halo was very faint over the southwest limb. The CME could reach Earth on
March 23.
[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 recurrent southern hemisphere coronal hole (CH1000) was Earth facing on March 17-19.
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 fair.
The geomagnetic field is expected to be quiet to active on March 21-22 due to effects from CH1000. Quiet to minor storm is possible on March 23-24 if the March 20 CME arrives.
| 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 red colored.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 12808 | 2021.03.08 2021.03.09 |
N19W74 |
|
||||||||
| 12810 | 2021.03.15 2021.03.16 |
2 | 7 | 3 | N18E13 | 0010 | AXX | BXO |
 |
 |
location: N19E15 |
| S6772 | 2021.03.17 | S26W32 | |||||||||
| S6773 | 2021.03.17 | N27W34 | |||||||||
| S6774 | 2021.03.17 | N06W25 | likely SC24 | ||||||||
| S6776 | 2021.03.18 | S03W43 | SC24 | ||||||||
| S6778 | 2021.03.18 | S30E16 | |||||||||
| S6780 | 2021.03.19 | S31W20 |
 |
||||||||
| S6781 | 2021.03.19 | S28E23 |
 |
||||||||
| S6782 | 2021.03.20 | 2 | S07W37 | 0002 | BXO |
 |
likely SC24 | ||||
| S6783 | 2021.03.20 | 3 | 1 | N20E73 | 0007 | AXX |
 |
||||
| Total spot count: | 2 | 12 | 4 | ||||||||
| Sunspot number: | 12 | 42 | 24 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 2 | 12 | 4 | (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): | 13 | 23 | 19 | k * (sunspot number) As of May 7, 2016: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.80 for MSN 1K (MSN=Magnetic Sunspot Number) |
|||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (cycle peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (cycle peak) |
| 2019.08 | 67.0 | 68.7 | 0.5 | 3.4 (-0.1) | 6.79 |
| 2019.09 | 67.9 | 68.7 | 1.1 | 3.1 (-0.3) | 9.81 |
| 2019.10 | 67.4 | 67.0 | 0.4 | 2.6 (-0.5) | 7.53 |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2020.01 | 72.2 | 69.9 | 6.4 | 2.2 (+0.4) | 4.39 |
| 2020.02 | 71.0 | 69.3 | 0.4 | 2.8 (+0.6) | 6.16 |
| 2020.03 | 70.2 | 69.5 | 1.5 | 3.0 (+0.2) | 5.63 |
| 2020.04 | 69.5 | 70.0 | 5.4 | 3.6 (+0.6) | 5.32 |
| 2020.05 | 69.0 | 70.6 | 0.2 | 5.6 (+2.0) | 3.80 |
| 2020.06 | 69.5 | 71.7 | 5.8 | 7.8 (+2.2) | 3.75 |
| 2020.07 | 69.5 | 71.8 | 6.3 | 8.8 (+1.0) | 4.28 |
| 2020.08 | 71.6 | 73.4 | 7.6 | 9.3 (+0.5) | 5.68 |
| 2020.09 | 70.7 | 71.4 | 0.7 | (10.2 projected, +0.9) | 8.59 |
| 2020.10 | 74.6 | 74.2 | 14.4 | (11.8 projected, +1.6) | 6.13 |
| 2020.11 | 89.9 | 88.0 | 34.0 | (14.3 projected, +2.5) | 4.77 |
| 2020.12 | 86.9 | 84.2 | 21.8 | (17.6 projected, +3.3) | 4.72 |
| 2021.01 | 76.0 | 73.6 | 10.4 | (21.3 projected, +3.7) | 4.39 |
| 2021.02 | 74.3 | 72.4 | 8.3 | (25.1 projected, +3.8) | 9.50 |
| 2021.03 | 75.7 (1) | 11.5 (2A) / 17.9 (2B) / 25.0 (2C) | (30.1 projected, +5.0) | (11.0) | |
| 2021.04 | (36.0 projected, +5.9) | ||||
| 2021.05 | (39.8 projected, +3.8) | ||||
| 2021.06 | (43.9 projected, +4.1) | ||||
| 2021.07 | (49.0 projected, +5.1) | ||||
| 2021.08 | (53.7 projected, +4.7) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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.
