Solar Terrestrial Activity Report

[Planetary A Index, Solar Flux and SEC sunspot number]

Last update January 25, 2000 at 05:55 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update January 1, 2000)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update January 1,
2000)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update January
1, 2000)]
[Historical solar and geomagnetic data charts 1954-1999]
[Experimental solar data chart January 1998-September 1999]

Recent development

The geomagnetic field was quiet to active on January 24. Solar wind speed
ranged between 342 and 407 km/sec.

Solar flare activity was low. Solar flux was 140.7, the planetary A index
was 17 (3-hour Kp indices: 1344 3332, Boulder K indices: 1345 3223). Region
8831 was quiet and stable, the region is rotating over the west limb.
Region 8833 was quiet and stable. Region 8838 was quiet and stable. Region
8839 did not change significantly and was quiet. Region 8840 was quiet and
stable. Region 8841 developed slowly and could produce further C flares.
Region 8842 developed further and is likely to produce C flares. Region
8843 was quiet and stable. New region 8844 emerged quickly in the northwest
quadrant.

Flares and CMEs

3 C flares were recorded on January 24. Region 8842 produced a C5.3 flare
at 21:31 UTC, while region 8841 generated a C1.3 flare at 22:11 UTC..

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

Coronal holes

A large trans equatorial coronal hole is rotating around the east limb. It
will rotate into a geoeffective position on January 25-29 and start a
geomagnetic disturbance on January 28.

Forecast

The geomagnetic field is expected to be quiet to unsettled on January
25-26. Low frequency (below 2 MHz) radio wave propagation along east-west
paths over high and upper middle latitudes is generally poor to very poor.

 Coronal holes (1)       Coronal mass      M and X class flares (3)
                         ejections (2)
 [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)

   Solar      Date      Actual no.  Location at
  region    numbered     sunspots    midnight   Area Classification Comment
   8831     20000112        1         S17W81    0060      HSX
   8833     20000113        1         N19W64    0100      HSX
   8835     20000115                  N11W64                        plage
   8836     20000116                  S13W54                         plage
   8838     20000118        6         N12W15    0020      CSO
   8839     20000120        10        N12W47    0050      CSO
   8840     20000121        3         S24W21    0010      AXX
   8841     20000121        7         S29E30    0120      DSO
   8842     20000123        8         S16W23    0050      DSO
   8843     20000123        4         N15E02    0010      BXO
   8844     20000124        3         N07W20    0020      DRO
 Total number of
 sunspots:                  43

Monthly solar data

  Month  Average solar   International sunspot     Smoothed sunspot
             flux                number                 number
 1998.12     150.1                81.9                77.9 (+4.9)
 1999.01     140.6                62.0                82.6 (+4.7)
 1999.02     141.9                66.3                84.6 (+2.0)
 1999.03     126.3                68.8                83.8 (-0.8)
 1999.04     117.2                63.7                85.4 (+1.6)
 1999.05     148.4               106.4                90.4 (+5.0)
 1999.06     169.8               137.7                93.0 (+2.6)

 1999.07