Last major update issued on May 23, 2004 at 04:15 UTC.
[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update May 3, 2004)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 3, 2004)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 3, 2004)]
[Historical solar and geomagnetic data charts 1954-2004 (last update April 28,
2004)]
[Archived reports (last update May 18, 2004)]
The geomagnetic field was quiet to active on May 22. Solar wind speed ranged between 449 and 535 km/sec under the influence of a high speed stream from coronal hole CH97.
Solar flux measured at 20h UTC on 2.8 GHz was 102.4. The planetary A
index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 12.3).
Three hour interval K indices: 23433222 (planetary), 33423312 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 4 spotted regions on the visible disk. The solar flare activity level was low. A total of 6 C class events was recorded during the day.
Region 10613 decayed slowly and quietly.
Region 10615 decayed slowly and quietly.
Region 10617 decayed further and could become spotless today.
Region 10618 developed further with most of the development occurring in the central section. The main penumbra has a
magnetic delta structure and an M class flare is possible. Flares: C1.7 at 01:19, C2.2 at
07:12, C1.4 at 11:55, C1.5 at 12:27, C2.0 at 13:02 and C1.0 at 17:34 UTC.
May 20-22: No fully or partly Earth directed CME observed.
Coronal hole history (since late October 2002)
Compare today's report with the situation one solar rotation ago: 28
days ago 27 days ago 26 days ago
A recurrent, poorly defined coronal hole (CH97) in the northern hemisphere was in a geoeffective position on May 19-20.
Processed SOHO/EIT 284 image at 19:05 UTC on May 22. The darkest areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be quiet to active on May 23 due to effects from a coronal hole flow. Quiet to unsettled is likely on May 24-26.
| 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) Material from a CME is likely to impact Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor. Propagation along long distance north-south paths is poor. Trans Atlantic propagation conditions are monitored every night on 1470 kHz. Dominant station tonight: Radio Vibración (Venezuela). WWZN Boston on 1510 kHz had a fair signal and the only unusual station was a Cuban on 1590 kHz at local sunrise.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SEC. 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 SEC or where SEC has observed no spots. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.
| Active region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10613 | 2004.05.13 | 2 | 1 | S09W42 | 0120 | HSX |
area was 0080 at midnight |
| 10615 | 2004.05.16 | 2 | 2 | N18W13 | 0100 | HSX |
area was 0080 at midnight |
| 10616 | 2004.05.16 | N07W09 | plage | ||||
| 10617 | 2004.05.17 | 5 | 2 | S10W60 | 0040 | CRO |
classification was AXX at midnight, area 0010, location S09W62 |
| 10618 | 2004.05.20 | 30 | 43 | S10E41 | 0310 | EAI |
beta-gamma-delta classification was EKI at midnight, location S10E39 |
| Total spot count: | 39 | 48 | |||||
| SSN: | 79 | 88 | |||||
| Month | Average solar flux at Earth |
International sunspot number | Smoothed sunspot number |
|---|---|---|---|
| 2000.04 | 184.2 | 125.5 | 120.8 cycle 23 sunspot max. |
| 2000.07 | 202.3 | 170.1 | 119.8 |
| 2001.12 | 235.1 | 132.2 | 114.6 (-0.9) |
| 2003.04 | 126.4 | 60.0 | 70.1 (-3.9) |
| 2003.05 | 115.7 | 55.2 | 67.6 (-2.5) |
| 2003.06 | 129.3 | 77.4 | 65.0 (-2.6) |
| 2003.07 | 127.7 | 83.3 | 61.8 (-3.2) |
| 2003.08 | 122.1 | 72.7 | 60.0 (-1.8) |
| 2003.09 | 112.2 | 48.7 | 59.5 (-0.5) |
| 2003.10 | 151.7 | 65.5 | 58.1 (-1.4) |
| 2003.11 | 140.8 | 67.3 | (56.5 predicted, -1.6) |
| 2003.12 | 114.9 | 46.5 | (53.5 predicted, -3.0) |
| 2004.01 | 114.1 | 37.2 | (49.1 predicted, -4.4) |
| 2004.02 | 107.0 | 46.0 | (44.8 predicted, -4.3) |
| 2004.03 | 112.0 | 48.9 | (42.1 predicted, -2.7) |
| 2004.04 | 101.2 | 39.3 | (40.0 predicted, -2.1) |
| 2004.05 | 99.0 (1) | 54.0 (2) | (36.8 predicted, -3.2) |
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2) Unofficial, accumulated value based on the Boulder (NOAA/SEC) sunspot number. The official international sunspot number is typically
30-50% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.
| [DX-Listeners' Club] |