Solar Terrestrial Activity Report

Last update issued on April 3, 2003 at 03:50 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update April 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update April 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update April 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update April 1, 2003)]

Recent activity

The geomagnetic field was quiet to active on April 2. Solar wind speed ranged between 446 and 555 km/sec under the influence of a high speed stream from coronal hole CH28.

Solar flux measured at 20h UTC on 2.8 GHz was 157.5. The planetary A index was 20 (STAR Ap - based on the mean of three hour interval ap indices: 21.5).
Three hour interval K indices: 24444334 (planetary), 33444433 (Boulder).

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

At midnight there were 9 spotted regions on the visible disk. Solar flare activity was low. A total of 6 C class events was recorded during the day.

Region 10321 lost all leader spots while slow development continued to the north of the largest trailing spot. C class flaring is possible as the region has become somewhat more complex. Flare: C1.0 at 17:13 UTC.
Region 10323 decayed quickly losing more than half of the penumbral area.
Region 10324 was quiet and stable. Please observe that SEC/NOAA has this as region 10328 while their region 10324 is region S129.
Region 10325 decayed slightly with all spots outside of the large penumbra disappearing.
Region 10326 was unchanged and quiet.
Region 10327 decayed slowly and quietly.

Spotted regions not yet numbered by SEC/NOAA:
[S129] A new region emerged northwest of region 10324 in the southeast quadrant on March 30. Location at midnight: S12W21. Please note that SEC/NOAA has this as region 10324! Flares: C1.8 at 00:14, C1.1 at 12:36, C3.6 at 15:16, C1.1 at 21:36 and C1.0 at 22:45 UTC.
[S130] A new region emerged on April 2 south southeast of region 10325 with quite a few spots. Location at midnight: N07E07.
[S131] A new region emerged in the northeast quadrant on April 2. Location at midnight: N01E30.

Coronal mass ejections (CMEs)

March 31-April 2: 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 coronal hole (CH29) in the southern hemisphere was in a geoeffective position on March 30-31. A small coronal hole (CH30) in the southern hemisphere will likely rotate into a geoeffective position on April 5. Another coronal hole (CH31) in the southern hemisphere will probably be in a geoeffective position on April 6-7.

Processed SOHO EIT 284 image at 01:06 UTC on April 3. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on April 3-4 due to a high speed stream from coronal hole CH29 and quiet to unsettled on April 5-7. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is very poor, propagation along north-south paths is fair. [Trans Atlantic propagation conditions are currently monitored every night on 1470 kHz. Dominant station tonight: 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
10318 2003.03.22 1   S13W76 0030 HRX now spotless
10319 2003.03.23 2   N12W88 0120 HSX rotated out of view
10321 2003.03.24 14 13 N07W40 0180 DAO beta-gamma
10323 2003.03.25 26 21 S07W56 0270 EAI classification was DAI
at midnight, area 0130
10324 2003.03.27 22 3 S12W12
(SEC:
S12W21)
0120 DAO location corrected,
SECs spots are those
of region S129
classification was AXX
at midnight, area 0000
10325 2003.03.27 21 2 N12E01
(SEC:
N10E05)
0310 EHI location corrected
SECs spots include
those of region S130
classification was HHX
at midnight, area 0300
10326 2003.03.28 2 2 S11E09 0030 HSX  
10327 2003.03.31 6 4 S05W38 0030 CRO classification was DSO
at midnight
10328 2003.03.31 5   S12W13 0010 AXX this is actually region
10324
S129 emerged on
2003.03.30
  30 S12W21 0200 DAI beta-gamma
see comment for
regions 10324, 10328
S130 emerged on
2003.04.02
  15 N07E07 0030 DSO see comment for
region 10325
S131 emerged on
2003.04.02
  5 N01E30 0030 CSO  
Total spot count: 99 95
SSN: 189 185

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)
2002.03 179.5 98.4 113.3 (-1.3)
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 (91.0 predicted, -3.6)
2002.11 168.7 95.0 (85.7 predicted, -5.3)
2002.12 157.2 81.6 (81.3 predicted, -4.4)
2003.01 144.0 79.5 (78.3 predicted, -3.0)
2003.02 124.5 46.2 (73.3 predicted, -5.0)
2003.03 131.4 61.5 (67.6 predicted, -5.7)
2003.04 155.3 (1) 11.7 (2) (62.7 predicted, -4.9)

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]