Solar Terrestrial Activity Report

Last update issued on May 8, 2003 at 02:50 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 major storm on May 7. Solar wind speed ranged between 600 and 769 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 110.2. The planetary A index was 36 (STAR Ap - based on the mean of three hour interval ap indices: 38.3).
Three hour interval K indices: 55654433 (planetary), 54654433 (Boulder).

The background x-ray flux is at the class B5 level.

At midnight there were 6 spotted regions on the visible disk. Solar flare activity was low. A total of 13 C class events was recorded during the day. An active region behind the northeast limb should soon rotate into view. This region produced a C2.2 flare at 10:27 and a C5.9 flare at 20:49 UTC and may be capable of minor M class flaring.

Region 10348 decayed further as it began to rotate over the southwest limb. A minor M class flare is possible today. Flares: C1.2 at 00:48, C1.4 at 01:28, C1.3 at 02:56, C4.2 at 07:10, C2.3 at 10:54, C1.2 at 15:54 and C2.0 at 20:32 UTC.
Region 10349 decayed further as most of the region rotated out of view at the southwest limb. Flares: C3.3 at 06:16, C1.8 at 13:12, C1.3 at 15:15 and C1.7 at 21:41 UTC.
Region 10351 was quiet and stable.
Region 10353 developed slowly adding a few small spots.
Region 10354 was quiet and stable.

Spotted regions not yet numbered by SEC/NOAA:
[S156] A new region emerged in the southeast quadrant on May 7. Location at midnight: S13E07.

Coronal mass ejections (CMEs)

May 5-7: 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 be in a geoeffective position on May 2-9.

Processed SOHO EIT 284 image at 19:06 UTC on May 7. 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 poor (1510 WWZN Boston audible for a couple of hours) and will likely stay poor to very poor until at least May 12. Propagation along north-south paths is fair to 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: At first a station from Brazil with soccer commentary, then Radio Cristal del Uruguay.]

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
10346 2003.04.24 1   N13W90 0060 HSX rotated out of view
10348 2003.04.26 15 14 S34W80 0420 FAI beta-gamma
10349 2003.04.26 14 2 S14W86 0450 EKI barely visible at
midnight
10351 2003.04.30 1 1 N08W15 0200 HSX  
10352 2003.05.01     S24W35     plage
10353 2003.05.04 6 5 S16W09 0010 BXO classification was CRO
at midnight
10354 2003.05.04 1 2 N19E21 0010 AXX classification was HSX
at midnight, area 0020
10355 2003.05.05 1 1 N13E17 0010 HRX now spotless
S156 emerged on
2003.05.07
  1 S13E07 0010 AXX  
Total spot count: 39 26
SSN: 109 96

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)
2003.05 134.6 (1) 33.3 (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]