Solar Terrestrial Activity Report

Last update issued on May 7, 2003 at 02:30 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update May 1, 2003)]
[Solar cycles 1-20]
[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 5, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on May 6. Solar wind speed ranged between 566 and 780 km/sec under the influence of a high speed stream from coronal hole CH38.

Solar flux measured at 20h UTC on 2.8 GHz was 122.0. The planetary A index was 23 (STAR Ap - based on the mean of three hour interval ap indices: 23.4).
Three hour interval K indices: 43345444 (planetary), 33345434 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was low. A total of 7 C class events was recorded during the day.

Region 10346 was quiet and stable. The region will be rotating over the northwest limb today.
Region 10348 developed in the leader spots, however, moderately quick decay was observed in other parts of the region. A minor M class flare is possible until the region rotates out of view on May 8. Flares: C2.0 at 20:47 and C2.6 at 21:14 UTC.
Region 10349 continued to decay quickly in all sections. A minor M class flare is possible until the region rotates behind the southwest limb on May 8. Flares: C3.2 long duration event peaking at 01:48, C5.7 long duration event peaking at 10:20, C3.7 at 14:10, C1.3 at 17:29 and C2.8 at 19:25 UTC.
Region 10351 was quiet and stable.
Region 10353 reemerged with a single spot.
Region 10354 was quiet and stable.
Region 10355 decayed and could soon become spotless.

Coronal mass ejections (CMEs)

May 4-6: No obviously geoeffective CMEs observed.

Coronal holes

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 huge recurrent coronal hole (CH38) in the southern hemisphere will rotate into a geoeffective position on May 2-9.

Processed SOHO EIT 284 image at 14:07 UTC on May 6. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm until May 11 due to a high speed stream from coronal hole CH38. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor and will likely remain that way until at least May 12. Propagation along north-south paths is good and is likely to be at least fair until May 12. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: None, several stations from Brazil were heard with good signal strength - the best night for Brazil since nightly monitoring started in late January. The usually dominant Radio Cristal del Uruguay surfaced briefly only a few times.]

Coronal holes (1) Coronal mass ejections (2) M and X class flares (3)
Coronal hole indicator CME indicator M and X class flare indicator

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.

Active solar regions (Recent map)

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
10345 2003.04.24 1   S17W86 0030 HSX now spotless
10346 2003.04.24 1 1 N14W77 0050 HSX  
10348 2003.04.26 18 21 S34W68 0560 FKI beta-gamma
area was 0450
at midnight
10349 2003.04.26 24 18 S15W71 0610 FKC beta-gamma
classification was EKC
at midnight, area 0330
10351 2003.04.30 1 1 N08W02 0190 HAX  
10352 2003.05.01     S24W22     plage
10353 2003.05.04   1 S16E07 0010 HRX  
10354 2003.05.04 1 1 N19E33 0030 HSX  
10355 2003.05.05 1 1 N12E31 0010 HSX classification was HRX
at midnight
S150 emerged on
2003.05.02
    S01W82     plage
Total spot count: 47 44
SSN: 117 114

Monthly solar cycle data

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)
2003.05 138.7 (1) 29.8 (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.


[DX-Listeners' Club]