The geomagnetic field was quiet on July 31. Solar wind speed at SOHO ranged between 330 and 445 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels.
Solar flux density measured at 20h UT on 2.8 GHz was 177.1 - increasing 9.9 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 149.98. In comparison SC24 peaked on June 28, 2014 at 145.50). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.5). Three hour interval K indices: 11222212 (planetary), 11313322 (Boulder), 22234424 (Andenes).
The background x-ray flux was at the class C3 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 12 active regions using 2K resolution (SN: 303) and in 11 active regions using 1K resolution (SN: 206) SDO/HMI images.
Region 13379 [N13W88] rotated mostly out of view and was quiet.
Region 13380 [S16W25] gained tiny trailing
spots and was quiet.
Region 13386 [N11W08] decayed slowly and was mostly quiet. C1 flares:
C1.7 @ 02:06 UT
Region 13387 [N21E17] was mostly quiet and stable.
Region 13388 [S23E09] was quiet and stable.
Region 13389 [S09E22] decayed slowly and quietly.
Region 13390 [S19E33] produced the only M flare of the day and a few
low level C flares. C1 flares: C1.8 @ 03:17 UT
Region 13391 [N24E51] was quiet and stable.
New region 13392 [N09E50] rotated into view on July 29 and was
numbered 2 days later by SWPC. The spot group gained spots and area on July
31.
New region 13393 [N17E26] emerged on July 29 with SWPC numbering the
region 2 days later.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S8813 [S10W39] developed quickly adding area
and becoming even more compact and complex. An area with positive polarity
is sandwiched between 2 areas of negative polarity. An X class flare is
possible. Two M flares have been recorded early on August 1. C1 flares: C1.4
@00:38, C1.5 @ 01:22 UT
New region S8814 [N19E73] rotated into view with tiny spots.
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.0 | 04:23 | 13387 | GOES16 | ||
| C6.8 | 04:47 | 13390 | GOES16 | ||
| C2.7 | 05:34 | behind southwest limb | 13385 | GOES16 | |
| C4.6 | 07:23 | S10W26 | S8813 | GOES16 | |
| C2.3 | 08:05 | S8813 | GOES16 | ||
| M1.7/2F | 09:00 | S20E44 | 13390 | GOES16 | |
| C4.5 | 09:49 | S8813 | GOES16 | ||
| C3.0/1F | 11:41 | S8813 | GOES16 | ||
| C2.8 | 11:49 | 13386 | GOES16 | ||
| C2.6 | 13:07 | S8813 | GOES16 | ||
| C2.7 | 15:13 | S8813 | GOES16 | incorrectly attributed to AR 13386 by SWPC | |
| C2.1 | 15:49 | behind southwest limb | 13385 | GOES16 | incorrectly attributed to AR 13386 by SWPC |
| C2.4 | 18:46 | S8813 | GOES16 | ||
| C2.4 | 19:06 | S8813 | GOES16 | ||
| C2.5 | 19:21 | S8813 | GOES16 | ||
| C3.2 | 21:09 | S8813 | GOES16 | ||
| C5.4 | 22:47 | S8813 | GOES16 | ||
| C5.7 | 23:06 | S8813 | GOES16 |
July 31: Several filaments erupted during the latter half of the day.
A partial halo CME was observed starting at 00:00 UT on August 1 in LASCO C2
imagery. It is unclear if the source was frontsided or backsided.
July 29-30: No obviously Earth directed CMEs were observed.
July 28: A large filament eruption was observed beginning in the
northeast quadrant at approximately 20:47 UT in SDO AIA imagery, and with a
peak after 22h UT. A faint full halo CME was observed in LASCO C2 imagery
beginning at 22:36 UT. The most likely source of the CME is the
aforementioned filament eruption. The brightest ejecta was off the southeast
limb. The CME could reach Earth late on July 31 or early on August 1.
[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 small coronal hole (CH1162) formed in the northeast quadrant near the central meridian after the filament eruption on July 28. CH1162 closed on July 29.
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.
The geomagnetic field is expected to be quiet to minor storm on August 1 due to effects from the July 28 CME. Effects from CH1162 could reach Earth on August 1 and contribute to the expected disturbance. Quiet to unsettled is likely on August 2-3.
| 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 | ||||||||||
| 13379 | 2023.07.18 2023.07.19 |
1 | 1 | N13W89 | 0100 | HSX | HSX |
 |
 |
||
| 13380 | 2023.07.22 2023.07.23 |
20 | 21 | 11 | S10W39 | 0310 | DKC | CRO |
 |
 |
location: S16W25 area: 0060 AR S8813 was split off on July 30 |
| 13382 | 2023.07.24 | N18W88 | part of AR 13379 | ||||||||
| 13383 | 2023.07.24 | N15W78 | part of AR 13379 | ||||||||
| S8793 | 2023.07.24 | S04W48 | |||||||||
| S8794 | 2023.07.24 | N17W52 | |||||||||
| 13384 | 2023.07.24 2023.07.25 |
8 | S16W15 | 0040 | CAO | part of AR 13380 | |||||
| 13386 | 2023.07.25 2023.07.26 |
24 | 32 | 22 | N10W04 | 0310 | EKI | EHO |
 |
 |
beta-gamma area: 0380 location: N11W08 |
| 13387 | 2023.07.26 2023.07.27 |
9 | 20 | 8 | N23E16 | 0110 | CSO | CSO |
 |
 |
area: 0170 location: N21E17 |
| 13388 | 2023.07.26 2023.07.27 |
2 | 9 | 4 | S23E07 | 0040 | HSX | CRO |
 |
 |
area: 0030 location: S23E09 |
| 13389 | 2023.07.27 2023.07.27 |
2 | 8 | 5 | S09E22 | 0030 | HSX | CRO |
 |
 |
area: 0070 |
| S8806 | 2023.07.27 | S15E10 | |||||||||
| 13390 | 2023.07.28 2023.07.27 |
2 | 11 | 4 | S20E34 | 0020 | DSO | DRO |
 |
 |
location: S19E33 area: 0050 |
| 13391 | 2023.07.28 2023.07.29 |
2 | 4 | 2 | N23E49 | 0130 | HSX | CSO |
 |
 |
area: 0200 location: N24E51 |
| 13392 | 2023.07.29 2023.07.31 |
3 | 25 | 12 | N09E50 | 0040 | DAI | DAI |
 |
 |
area: 0120 |
| S8811 | 2023.07.29 | S07W12 |
 |
||||||||
| 13393 | 2023.07.29 2023.07.31 |
3 | 7 | 3 | N16E26 | 0060 | HSX | CRO |
 |
 |
area: 0020 |
| S8813 | 2023.07.30 | 43 | 24 | S10W39 | 0720 | DKC | DAC |
 |
 |
beta-delta split off from AR 13380 |
|
| S8814 | 2023.07.31 | 2 | 1 | N19E73 | 0007 | HRX |
 |
||||
| Total spot count: | 76 | 183 | 96 | ||||||||
| Sunspot number: | 186 | 303 | 206 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 141 | 236 | 149 | (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): | 205 | 167 | 165 | ||||||||
| 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 |
| 2022.01 | 103.8 | 100.5 | 55.3 | 60.1 (+4.2) | 8.92 |
| 2022.02 | 109.1 | 106.5 | 60.9 | 64.7 (+4.6) | 10.46 |
| 2022.03 | 117.0 | 115.8 | 78.6 | 68.7 (+4.0) | 10.20 |
| 2022.04 | 130.8 | 131.7 | 84.0 | 73.0 (+4.3) | 11.79 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 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 | 92.5 (+5.8) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.4 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.7 (+2.3) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.0 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.6 (+5.6) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 143.6 | 113.3 (+6.7) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 110.9 | (119.1 projected, +5.8) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 122.6 | (124.4 projected, +5.3) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 96.4 | (130.5 projected, +6.1) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.9 | (136.1 projected, +5.6) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 163.4 | (139.3 projected, +3.2) | 8.95 |
| 2023.07 | 176.4 | 182.2 | 159.1 | (139.7 projected, +0.4) | 8.1 |
| 2023.08 | (1) | (2A/2B) / 151.1 (2C) | (141.5 projected, +1.8) | () | |
| 2023.09 | (145.0 projected, +3.5) | ||||
| 2023.10 | (146.8 projected, +1.8) | ||||
| 2023.11 | (149.4 projected max SC25, +2.6) | ||||
| 2023.12 | (148.6 projected, -0.8) | ||||
| 2024.01 | (145.7 projected, -2.9) | ||||
| 2024.02 | (144.3 projected, -1.4) | ||||
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
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.
