Solar Terrestrial Activity Report

Last update issued on May 24, 2003 at 03:20 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 19, 2003)]

Recent activity

The geomagnetic field was unsettled to minor storm on May 23. Solar wind speed ranged between 443 and 509 km/sec under the influence of a high speed stream from coronal hole CH40.

Solar flux measured at 20h UTC on 2.8 GHz was 117.9. The planetary A index was 21 (STAR Ap - based on the mean of three hour interval ap indices: 21.1).
Three hour interval K indices: 34453433 (planetary), 24342323 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight there were 7 spotted regions on the visible disk. Solar flare activity was very low.

Region 10362 decayed and could soon become spotless.
Region 10365 decayed significantly and had only a single small spot left at the end of the day. The region could become spotless today or tomorrow.
Region 10366 was quiet and unchanged.
Region 10367 added some penumbral area and was quiet.
Region 10368 was quiet and stable.
New region 10369 emerged in the northeast quadrant on May 22 and was numbered the next day by SEC.
New region 10370 rotated into view at the northeast limb on May 22 and was numbered the next day by SEC.

Coronal mass ejections (CMEs)

May 21-23: 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 recurrent trans equatorial coronal hole (CH40) was in a geoeffective position on May 18-21. A recurrent coronal hole (CH41) in the southern hemisphere will rotate into a geoeffective position on May 24.

Processed SOHO EIT 284 image at 19:06 UTC on May 23. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active on May 24 due to a high speed stream from coronal hole CH40, and quiet to active on May 25 and quiet to unsettled on May 26. On May 27 a high speed stream from coronal hole CH41 will likely arrive and cause unsettled to minor storm conditions that day and on May 28.

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 29. Propagation along north-south paths is poor. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: none, weak signals noted from Radio Cristal del Uruguay and Cadena Peruana de Noticias.]

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
10357 2003.05.11     S16W86     plage
10361 2003.05.15     N10W66     plage
10362 2003.05.15 7 7 S11W30 0050 DAO area was 0030
at midnight
10363 2003.05.18     S08W69     plage
10364 2003.05.19     S26W80     plage
10365 2003.05.20 1 2 S09E25 0020 HSX classification was HRX
at midnight, area 0010
10366 2003.05.22 2 2 N10E50 0020 BXO  
10367 2003.05.22 1 2 S14E55 0030 HSX area was 0060
at midnight
10368 2003.05.22 1 2 S32E62 0170 HAX  
10369 2003.05.23 4 5 N12E08 0020 CAO formerly region S168
classification was HRX
at midnight
10370 2003.05.23 1 1 N16E53 0020 AXX formerly region S167
area was 0010
at midnight
S163 emerged on
2003.05.19
    N20W79     plage
S165 emerged on
2003.05.21
    S13E15     plage
Total spot count: 17 21
SSN: 87 91

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)
2003.05 113.5 (1) 69.0 (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 30-50% 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]