Solar Terrestrial Activity Report

Last update issued on June 3, 2003 at 03:40 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 3, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2003)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2003)]
[Historical solar and geomagnetic data charts 1954-2003 (last update April 13, 2003)]
[Archived reports (last update June 1, 2003)]

Recent activity

The geomagnetic field was unsettled to major storm on June 2. Solar wind speed ranged between 586 and 767 km/sec under the influence of a high speed stream from coronal hole CH42.

Solar flux measured at 20h UTC on 2.8 GHz was 121.4. The planetary A index was 39 (STAR Ap - based on the mean of three hour interval ap indices: 39.3).
Three hour interval K indices: 54664434 (planetary), 34553334 (Boulder).

The background x-ray flux is at the class B8 level.

At midnight there were 3 spotted regions on the visible disk. Solar flare activity was high. A total of 9 C and 4 M class events was recorded during the day. Region S169 behind the southwest limb produced a major M7.0 flare (associated with a strong type II and a weak type IV radio sweep) at 00:22, a C3.1 flare at 04:10, a C2.0 flare 06:54, an M4.0 flare at 08:37, a C4.3 flare at 11:06, an M1.0 flare at 13:17 and a C9.3 flare at 15:44 UTC. Please note that NOAA/SEC in their daily flare reports has mixed data from GOES10 and GOES12. While claiming to use GOES12 data, they are actually reporting GOES10 flare intensities, i.e. the M7.0 flare recorded by GOES12 was recorded as M6.5 by GOES10. Another noteworthy example was a couple of days ago when an X1.0 flare (recorded by GOES12) in region S169, was reported as M9.3 (recorded by GOES10).

Region 10373 decayed slowly and quietly.
Region 10375 developed slowly. The region is fairly complex with two magnetic delta structures. A new delta developed during the day as negative flux emerged at the southern edge of southernmost penumbra. The main delta structure is in the large northern penumbra. Further M class flaring is highly likely. Flares: C2.0 at 04:26, C7.6 at 11:54, C8.0 at 12:17, M1.8 at 17:33, a long duration C3.2 event peaking at 19:28 and C3.8 at 21:47 UTC.
New region 10376 emerged quickly early in the day in the southeast quadrant. The region is simply structured.

Coronal mass ejections (CMEs)

June 1-2: Several CMEs were observed off of the west and east limbs, all of them appeared to be the result of activity in limb regions S169 and 10375.

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 (CH42) in the southern hemisphere will rotate into a geoeffective position on May 29-June 6.

Processed SOHO EIT 284 image at 19:06 UTC on June 2. Any black areas on the solar disk are likely coronal holes.


The geomagnetic field is expected to be unsettled to minor storm until June 9 due to a high speed stream from coronal hole CH42.

Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is useless and will likely be very poor to useless until at least June 10. Propagation along north-south paths is fair to good. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. Other frequencies were more interesting as reception improved a lot during the listening session, particularly 1480 kHz which had one station from Uruguay and one from Argentina.]

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 NOAA/SEC. 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
Location at midnight Area Classification Comment
10366 2003.05.22     N11W81     plage
10367 2003.05.22     S14W74     plage
10368 2003.05.22 1   S32W63 0010 AXX now spotless
10370 2003.05.23     N16W78     plage
10371 2003.05.27     S13W88     plage
10372 2003.05.27     S14W81     plage
10373 2003.05.27 10 10 N06E00 0160 CSO  
10375 2003.06.01 6 17 N12E64 0370 DSO beta-gamma-delta
classification was DKO
at midnight
10376 2003.06.02 4 10 S12E13 0030 CRO classification was DAO
at midnight, area 0080
S171 emerged on
    S23W63     plage
S172 emerged on
    S17W44     plage
S173 emerged on
    N05W21     plage
S174 emerged on
    N18W40     plage
S175 emerged on
    N14W11     plage
Total spot count: 21 37
SSN: 61 67

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)
2002.05 178.4 120.8 108.8 (-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 85.2 (-5.3)
2002.12 157.2 80.8 (81.4 predicted, -3.8)
2003.01 144.0 79.5 (78.3 predicted, -3.1)
2003.02 124.5 46.2 (73.3 predicted, -5.0)
2003.03 131.4 61.5 (67.6 predicted, -5.7)
2003.04 126.4 60.0 (62.7 predicted, -4.9)
2003.05 115.7 55.2 (57.8 predicted, -4.9)
2003.06 116.9 (1) 4.2 (2) (53.8 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 (NOAA/SEC) 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]