Last update issued on May 18, 2003 at 02:50 UTC.
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[Solar cycles 21-23 (last update May 1, 2003)]
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[Graphical comparison of cycles 21, 22 and 23 (last update May 1, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update May 1, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update May 12, 2003)]
The geomagnetic field was quiet to unsettled on May 17. Solar wind speed ranged between 449 and 563 km/sec.
Solar flux measured at 20h UTC on 2.8 GHz was 102.4. The planetary A
index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.6).
Three hour interval K indices: 33323211 (planetary), 23323312 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight there were 3 spotted regions on the visible disk. Solar flare activity was very low.
Region 10357 developed slowly and quietly. Minor polarity intermixing is currently evident in the leader spots where
there is little separating the negative polarity field in the north and the positive polarity field in the south
Region 10362 added some area to the leading penumbra and was otherwise mostly unchanged. The presence of small negative
polarity areas near the trailing positive polarity spots could make the region more interesting in the days ahead.
Spotted regions not numbered by SEC/NOAA:
[S160] A new region emerged in the southeast quadrant on May 17. Location at midnight: S08E08.
May 15-17: No obviously geoeffective CMEs 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 trans equatorial coronal hole (CH39) was in a geoeffective position on May 15-16. A recurrent trans equatorial coronal hole (CH40) will rotate into a geoeffective position on May 18-20.
Processed SOHO EIT 284 image at 01:06 UTC on May 18. Any black areas on the solar disk are likely coronal holes.
The geomagnetic field is expected to be initially quiet to unsettled on May 18. A high speed stream from coronal hole CH39 will likely reach Earth during the latter half of May 18 and cause unsettled to active geomagnetic conditions. This coronal flow will likely last until late on May 19 or early on May 20. A high speed stream from coronal hole CH40 is expected to influence the field May 21-24 and cause unsettled to active conditions with a possibility of occasional minor storm intervals. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely be very poor until at least May 25. Propagation along north-south paths is fair to good and is likely to be at least fair until May 25. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay with a good signal early on, then becoming fair.]
| 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.
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.
Compare to the previous day's image.
Data for all numbered solar regions according to the Solar Region Summary provided by SEC/NOAA. 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.
| Solar region | Date numbered | SEC spot count |
STAR spot count |
Location at midnight | Area | Classification | Comment |
|---|---|---|---|---|---|---|---|
| 10356 | 2003.05.09 | 4 | N18W44 | 0010 | BXO | now spotless | |
| 10357 | 2003.05.11 | 11 | 8 | S15W06 | 0050 | DAO | |
| 10358 | 2003.05.12 | 3 | N08W46 | 0010 | HRX | now spotless | |
| 10359 | 2003.05.12 | S14W88 | rotated out of view | ||||
| 10360 | 2003.05.14 | S05W60 | plage | ||||
| 10361 | 2003.05.15 | 3 | N09E10 | 0010 | AXX | now spotless | |
| 10362 | 2003.05.15 | 10 | 9 | S11E50 | 0210 | DAO | |
| S158 | emerged on 2003.05.14 |
S10W85 | plage | ||||
| S160 | emerged on 2003.05.17 |
1 | S08E08 | 0010 | HRX | ||
| Total spot count: | 31 | 18 | |||||
| SSN: | 81 | 48 | |||||
| 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) |
| 2002.04 | 189.8 | 120.7 | 110.5 (-2.9) |
| 2002.05 | 178.4 | 120.8 | 108.8 (-1.7) |
| 2002.06 | 148.7 | 88.3 | 106.2 (-2.6) |
| 2002.07 | 173.5 | 99.6 | 102.7 (-3.5) |
| 2002.08 | 183.6 | 116.4 | 98.7 (-4.0) |
| 2002.09 | 175.8 | 109.6 | 94.6 (-4.1) |
| 2002.10 | 167.0 | 97.5 | 90.5 (-4.1) |
| 2002.11 | 168.7 | 95.5 | (84.9 predicted, -5.6) |
| 2002.12 | 157.2 | 80.8 | (80.5 predicted, -4.4) |
| 2003.01 | 144.0 | 79.5 | (77.5 predicted, -3.0) |
| 2003.02 | 124.5 | 46.2 | (72.4 predicted, -5.1) |
| 2003.03 | 131.4 | 61.5 | (66.8 predicted, -5.6) |
| 2003.04 | 126.4 | 60.0 | (61.9 predicted, -4.9) |
| 2003.05 | 112.8 (1) | 52.6 (2) | (57.9 predicted, -4.0) |
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 (SEC/NOAA) sunspot number. The official international sunspot number is typically 25-45% less.
This report has been prepared by Jan Alvestad. It is based partly on my own observations and interpretations, and partly on data from sources noted in solar links. All time references are to the UTC day. Comments and suggestions are always welcome.
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