The geomagnetic field was quiet to active on
April 9, after 07 under the influence of a high speed stream
from CH860. Solar wind speed at SOHO ranged between 336 and 515
km/s.
Solar flux at 20h UTC on 2.8 GHz was 68.7 (increasing 0.1 over the previous solar rotation). The average 90 day 10.7 flux at 1 AU was 68.5. The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 21212224 (planetary), 22323324 (Boulder)
The background x-ray flux is at the class A1 level.
At the time of counting spots (see image time), spots were observed in 4 active regions using 2K resolution (SN: 45) and in 1 active region using 1K resolution (SN: 11) SDO images on the visible solar disk.
Spotted regions not numbered (or
interpreted differently) by SWPC:
S5935 [S11W59] was quiet and stable.
New region S5936 [S31E02] emerged
early in the day as a bipolar cycle 25 region. The trailing
spot disappeared late in the day.
New region S5937 [N03E25] emerged with a tiny
spot.
New region S5938 [N04W56] emerged with a tiny spot.
| Magnitude | Peak time (UT) | Location | AR | Recorded by | Comment |
| |
April 7-9: No obviously Earth directed CMEs were observed in available LASCO imagery.
[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 trans equatorial coronal hole
(CH860) will rotate into an Earth facing position on April 6-12.
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 fair.
The geomagnetic field is expected to be quiet
to minor storm on April 10-14 due to effects from CH860.
| 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 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 detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC | Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| 12703 | 2018.03.29 2018.03.30 |
S08W78 | |
||||||||
| S5931 | 2018.04.05 |
S06E04 | |
||||||||
| S5932 | 2018.04.05 |
S21W08 | |
||||||||
| S5935 | 2018.04.08 |
1 |
S11W59 | 0001 |
AXX |
 |
 |
||||
| S5936 | 2018.04.09 |
1 |
1 |
S31E02 | 0008 |
HRX |
 |
|
cycle 25 region |
||
| S5937 | 2018.04.09 |
2 |
N03E25 |
0002 |
BXO |
 |
|
|
|||
| S5938 | 2018.04.09 |
1 |
S31E02 | 0001 |
AXX |
 |
|
|
|||
| Total spot count: | 0 |
5 |
1 |
||||||||
| Sunspot number: | 0 |
45 |
11 |
(total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 0 |
8 |
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): | 0 |
25 |
9 |
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) (4) |
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 |
| 2016.09 | 87.7 | 88.7 | 44.7 | 33.3 (-2.7) | 14.54 |
| 2016.10 | 86.1 | 85.6 | 33.6 | 31.4 (-1.9) | 15.33 |
| 2016.11 | 78.6 | 76.9 | 21.4 | 29.9 (-1.5) | 9.11 |
| 2016.12 | 75.1 | 72.8 | 18.9 | 28.5 (-1.4) | 9.34 |
| 2017.01 | 77.3 | 74.9 | 25.8 | 27.9 (-0.6) | 9.45 |
| 2017.02 | 76.8 | 75.0 | 26.1 | 26.6 (-1.3) | 9.58 |
| 2017.03 | 74.6 | 73.9 | 17.7 | 25.8 (-0.8) | 14.20 |
| 2017.04 | 80.3 | 80.8 | 32.6 | 24.9 (-0.9) | 11.70 |
| 2017.05 | 73.6 | 75.2 | 18.8 | 23.4 (-1.5) | 8.09 |
| 2017.06 | 74.7 | 77.1 | 19.4 | 22.3 (-1.1) | 6.08 |
| 2017.07 | 77.4 | 79.9 | 18.3 | 21.0 (-1.3) | 8.97 |
| 2017.08 | 77.9 | 79.8 | 33.1 | 19.5 (-1.5) | 10.66 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.3 (-1.2) | 18.22 (cycle peak) |
| 2017.10 | 76.4 | 75.6 | 13.2 | (16.5 projected, -1.8) | 10.30 |
| 2017.11 | 72.2 | 70.6 | 5.7 | (14.6 projected, -1.9) | 10.06 |
| 2017.12 | 71.6 | 69.3 | 8.2 | (13.3 projected, -1.3) | 7.33 |
| 2018.01 | 69.9 | 67.7 | 6.7 | (12.3 projected, -1.0) | 5.53 |
| 2018.02 | 72.0 | 70.2 | 10.6 | (10.5 projected, -1.8) | 6.40 |
| 2018.03 | 68.3 | 67.6 | 2.5 | (7.6 projected, -2.9) | 7.5 |
| 2018.04 | (67.9) | 0 (2A) / 0 (2B) / 3.7 (2C) | (5.7 projected, -1.9) | (4.6) | |
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) 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.
