Solar Terrestrial Activity Report

Last update issued on February 27, 2003 at 03:40 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update February 2, 2003)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update February 2, 2003)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update February 2, 2003)]
[Historical solar and geomagnetic data charts 1954-2002 (last update January 27, 2003)]
[Archived reports (last update February 24, 2003)]

Recent activity

The geomagnetic field was quiet to active on February 26. Solar wind speed ranged between 358 and 468 km/sec.

Solar flux measured at 20h UTC on 2.8 GHz was 109.4. The planetary A index was 16 (STAR Ap - based on the mean of three hour interval ap indices: 17.6).
Three hour interval K indices: 12443334 (planetary), 12343324 (Boulder).

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

At midnight there were 5 spotted regions on the visible disk, 3 of which have not yet been numbered by SEC/NOAA. Solar flare activity was very low.

Region 10290 decayed quietly.
Region 10292 decayed slowly and quietly.

Spotted regions not yet numbered by SEC/NOAA:
[S108] A new region emerged early on February 26 near the southeast limb. Location at midnight: S06E55.
[S109] A new region emerged in the southeast quadrant early on February 26. Location at midnight: S20E40.
[S110] A new region rotated into view at the southeast limb. This region appears to be capable of C class flaring. Location at midnight: S19E76.

Coronal mass ejections (CMEs)

February 24: No obviously geoeffective CMEs observed.

No new LASCO images will become available until Feb.27 or 28 thus preventing CME analysis.

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 (CH21) was in a geoeffective position on February 23-24. The northernmost part of a coronal hole (CH22) in the southern hemisphere may have been geoeffective on February 26-27. A coronal hole (CH23) in the northern hemisphere will rotate into a geoeffective position on March 1.

Processed SOHO EIT 284 image at 01:06 UTC on February 27. Any black areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on February 27 and quiet to active on February 28-March 2 due to high speed streams from coronal holes (CH21 and CH22). 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. [Propagation conditions are currently monitored every night. Main monitoring frequency: 1470 kHz. Dominant station tonight: Radio Cristal del Uruguay. After s/off several weak stations observed. On Febr.26 Rádio Mensagem, Jacarei (SP), Brazil was identified at 03h UTC.]

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
10288 2003.02.15 1   N16W81 0050 HSX now spotless
10290 2003.02.18 7 6 N18W60 0140 DAO classification was CAO
at midnight, area 0090
10291 2003.02.21     S23W60     plage
10292 2003.02.25 7 3 S08W28 0030 CSO classification was HSX
at midnight, area 0020
S105 emerged on
2003.02.20
  S28W68     plage
S106 emerged on
2003.02.23
    S06W20     plage
S108 emerged on
2003.02.26
  2 S06E55 0010 BXO  
S109 emerged on
2003.02.26
  3 S20E40 0010 BXO  
S110 emerged on
2003.02.26
  4 S19E76 0040 CAO  
Total spot count: 15 18
SSN: 45 68

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)
2002.01 226.6 114.1 113.5 (-1.1)
2002.02 205.0 107.4 114.6 (+1.2)
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 (99.7 predicted, -3.0)
2002.09 175.8 109.6 (96.7 predicted, -3.0)
2002.10 167.0 97.5 (93.2 predicted, -3.5)
2002.11 168.7 95.0 (88.0 predicted, -5.2)
2002.12 157.2 81.6 (83.6 predicted, -4.4)
2003.01 144.0 79.5 (80.6 predicted, -3.0)
2003.02 124.8 (1) 82.4 (2) (75.5 predicted, -5.1)

1) Running average based on the daily 20:00 UT 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.


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