The geomagnetic field was very quiet on February 2. Solar wind speed at SOHO ranged between 308 and 375 km/sec. The high latitude magnetometer at Andenes recorded very quiet levels. The above 10 MeV proton flux was slightly elevated at 0.6 pfu at the end of the day.
Solar flux density measured at 20h UT on 2.8 GHz was 142.6 - decreasing 16.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.05. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). The Potsdam WDC planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 1.6). Three hour interval K indices: 00110000 (planetary), 01222111 (Boulder), 10001001(Andenes).
The background x-ray flux is at the class C1 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 14 active regions using 2K resolution (SN: 273) and in 9 active regions using 1K resolution (SN: 155) SDO/HMI images.
Region 13565 [N06W01] decayed slowly and
was mostly quiet.
Region 13567 [N19E22] decayed quickly leaving no spots with mature
penumbra. C1 flares: C1.0 @ 05:15 UT
Region 13568 [S09W75] was quiet and stable.
Region 13570 [S04E36] developed slowly and
quietly.
Region 13571 [S17E50] continued to be the most active region on the
visible disk producing one M flare and many C flares. The region has
polarity intermixing with tiny positive polarity spots near the large
negative polarity spot. C1 flares: C1.0 @ 01:55, C1.2 @ 21:16 UT
Region 13572 [S11E08] decayed slowly and quietly.
Region 13573 [N22W05] was mostly quiet and stable.
C1 flares: C1.1 @ 01:16 UT
Region 13574 [N15E58] was quiet and stable.
New region 13575 [S36W23] emerged on January 31 and was noticed by
SWPC 2 days later as the region continued to develop. C and minor M class
flares are possible. A large magnetic delta structure formed early on
February 3. C1 flares: C1.7 @ 08:19 UT
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9366 [N20W22] was mostly quiet and stable.
S9371 [S08W18] was mostly quiet and stable.
S9395 [N28E09] was quiet and stable.
New region S9397 [N09W73] emerged with a tiny spot.
New region S9398 [N25E60] emerged with a tiny spot.
An active region behind the southeast limb produced a C1.5 flare at 09:13, a C1.4 flare at 17:15 and a C1.6 flare at 19:23 UT. This region is rotating into view at S15 early on February 3 and is AR S9399.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| M1.1 | 03:01 | 13571 | GOES16 | CME | |
| C3.2 | 05:30 | 13571 | GOES16 | ||
| C5.6/1N | 10:57 | S20E57 | 13571 | GOES16 | |
| C6.5 | 11:35 | behind southeast limb | S9399 | GOES16 | weak type II radio sweep |
| C2.4 | 13:16 | 13571 | GOES16 | ||
| C3.0 | 15:34 | 13571 | GOES16 | ||
| C3.1 | 16:32 | 13571 | GOES16 | ||
| C2.5 | 16:48 | 13565 | GOES16 |
January 31, February 2: No obviously Earth directed CMEs were observed.
February 1: A C3.0 flare in AR S9366 peaking at 07:43 UT was
associated with a partial halo CME where the major part of the ejecta was
observed off the northeast limb and the north pole. A solar wind shock
associated with this CME is possible on February 4.
[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 positive polarity southern hemisphere coronal hole (CH1201) was Earth facing on February 1-2.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on February 3. Quiet to active is possible on February 4-5 due to CME effects and effects from CH1201.
| Coronal holes (1) | Coronal mass ejections (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 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 | ||||||||||
| S9366 | 2024.01.25 | 5 | 1 | N20W22 | 0010 | BXO |
 |
 |
|||
| S9367 | 2024.01.25 | N31W56 | |||||||||
| 13563 | 2024.01.26 2024.01.26 |
S05W68 | location: S07W59 | ||||||||
| S9370 | 2024.01.26 | N15W51 | |||||||||
| S9371 | 2024.01.26 | 8 | 4 | S08W18 | 0025 | BXO |
 |
 |
|||
| S9375 | 2024.01.26 | S21W51 | |||||||||
| 13568 | 2024.01.27 2024.01.30 |
1 | S10W78 | 0001 | AXX |
 |
 |
location: S09W75 |
|||
| S9379 | 2024.01.27 | N31W57 | |||||||||
| 13565 | 2024.01.27 2024.01.28 |
8 | 23 | 13 | N07W01 | 0020 | DRI | DRI |
 |
 |
beta-gamma location: N06W01 area: 0050 |
| 13564 | 2024.01.28 | S14W17 | SWPC position on Feb.1: S09E14 | ||||||||
| 13567 | 2024.01.28 2024.01.30 |
21 | 32 | 16 | N19E22 | 0180 | DAI | ERI |
 |
 |
area: 0120 |
| 13569 | 2024.01.28 | S12W38 |
 |
location: S13W35 | |||||||
| S9383 | 2024.01.29 | S16W56 | |||||||||
| S9384 | 2024.01.29 | S35W36 | |||||||||
| S9387 | 2024.01.30 | N11W52 | |||||||||
| 13570 | 2024.01.30 2024.02.01 |
5 | 19 | 9 | S04E35 | 0020 | DRO | DRI |
 |
 |
area: 0050 location: S04E35 |
| 13572 | 2024.01.31 2024.02.01 |
2 | 1 | S12E08 | 0010 | AXX | AXX |
 |
 |
area: 0002 | |
| 13571 | 2024.01.31 2024.02.01 |
2 | 7 | 1 | S17E49 | 0110 | HSX | CKO |
 |
 |
beta-gamma location: S17E50 area: 0300 |
| 13575 | 2024.01.31 2024.02.02 |
8 | 25 | 16 | S37W25 | 0020 | BXO | DRI |
 |
 |
location: S36W23 area: 0140 |
| 13573 | 2024.02.01 2024.02.01 |
3 | 3 | 2 | N23W06 | 0040 | CSO | DAO |
 |
 |
location: N22W05 area: 0060 |
| 13574 | 2024.02.01 2024.02.01 |
2 | 6 | 3 | N15E58 | 0090 | DSO | DSO |
 |
 |
area: 0160 |
| S9394 | 2024.02.01 | N23W09 |
 |
||||||||
| S9395 | 2024.02.01 | 1 | N28E09 | 0002 | AXX |
 |
 |
||||
| S9396 | 2024.02.01 | S14W27 |
 |
||||||||
| S9397 | 2024.02.02 | 1 | N09W73 | 0002 | AXX |
 |
|||||
| S9398 | 2024.02.02 | 1 | N25E60 | 0001 | AXX |
 |
|||||
| Total spot count: | 51 | 133 | 65 | ||||||||
| Sunspot number: | 131 | 273 | 155 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 77 | 165 | 97 | (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): | 144 | 150 | 124 | ||||||||
| 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 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 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 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.6 (+5.9) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.5 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.9 (+2.4) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.2 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.7 (+5.5) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.3 (+6.6) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.8 (+3.5) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 123.3 | 121.1 (+3.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 97.6 | 122.9 (+1.8) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.4 | 124.1 (+1.2) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.2 (+1.1) (SC25 solar max candidate) |
8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | 124.3 (-0.9) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | (123.4 projected, -0.9) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | (123.1 projected, -0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | (123.9 projected, +0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | (123.9 projected, +0.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | (120.5 projected, -3.4) | 9.60 |
| 2024.01 | 164.5 | 159.3 | 123.0 | (117.1 projected, -3.3) | 5.6 |
| 2024.02 | 139.8 (1) | 8.4 (2A) / 122.0 (2B) / 165.6 (2C) | (116.3 projected, -0.8) | (3.2) | |
| 2024.03 | (115.8 projected, -0.5) | ||||
| 2024.04 | (115.7 projected, -0.1) | ||||
| 2024.05 | (117.0 projected, +1.3) | ||||
| 2024.06 | (116.2 projected, -0.8) | ||||
| 2024.07 | (114.5 projected, -1.7) | ||||
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: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
The relatively low solar activity during the last months of 2023 significantly increased the possibility that solar cycle 25 has already peaked. Whether the first peak in June 2023 will be the actual solar max will not be known for some time. Due to the relatively high solar activity early in 2023 it is unlikely there will be another solar max candidate, if at all, until at least May 2024. Both the northern and southern polar fields, as well as the averaged total field, have already reversed polarities.
--------------------------------------------------------------------------------------
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.
