Solar Terrestrial Activity Report

Last update issued on May 23, 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 quiet to minor storm on May 22. Solar wind speed ranged between 451 and 528 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 118.4. The planetary A index was 25 (STAR Ap - based on the mean of three hour interval ap indices: 26.0).
Three hour interval K indices: 55434432 (planetary), 55424433 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight there were 8 spotted regions on the visible disk. Solar flare activity was low. A total of 4 C class events was recorded during the day.

Region 10362 decayed slowly but still has mixed polarities in the trailing spot section. Flare: C1.1 at 06:16, C4.9 at 07:03, C1.2 at 17:32 and C1.1 at 21:14 UTC.
Region 10364 decayed and had only a single small spot left at the end of the day. The region will likely become spotless before rotating over the southwest limb.
Region 10365 decayed and lost penumbral area in the northern part.
New region 10366 emerged early in the day at the northeast limb.
New region 10367 rotated into view at the southeast limb on May 21 and was numbered by SEC the next day.
New region 10368 rotated into view at a high latitude at the southeast limb early in the day.

Spotted regions not numbered by SEC/NOAA:
[S167] A new region rotated into view at the northeast limb on May 22. Location at midnight: N16E67.
[S168] A new region emerged slowly in the northeast quadrant late on May 22. Location at midnight: N12E19.

Coronal mass ejections (CMEs)

May 20-22: 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 22. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to active on May 23-24 due to a high speed stream from coronal hole CH40 and quiet to active on May 25.

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 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 Radio Vibración (Venezuela).]

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 8   S16W73 0060 CSO now spotless
10361 2003.05.15     N10W53     plage
10362 2003.05.15 15 14 S11W15 0100 DSO beta-gamma
10363 2003.05.18     S08W56     plage
10364 2003.05.19 9 1 S26W67 0050 DAO classification was HSX
at midnight, area 0020
10365 2003.05.20 4 5 S07E38 0040 CSO classification was HSX
at midnight, only
negative polarity spots
10366 2003.05.22 2 2 N11E62 0020 AXX classification was BXO
at midnight
10367 2003.05.22 1 3 S14E69 0050 CAO formerly region S166
classification was HAX
at midnight
10368 2003.05.22 1 1 S32E76 0180 HAX  
S162 emerged on
2003.05.19
    S24W79     plage
S163 emerged on
2003.05.19
    N20W53     plage
S165 emerged on
2003.05.21
    S13E41     now spotless
S167 visible on
2003.05.22
  2 N16E67 0010 BXO  
S168 emerged on
2003.05.22
  3 N12E19 0010 BXO  
Total spot count: 40 31
SSN: 110 111

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)
2003.05 113.3 (1) 66.2 (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]