Solar Terrestrial Activity Report

Last update June 5, 2001 at 04:00 UTC.

[Solar and geomagnetic data - last 4 weeks (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-23 (last update June 3, 2001)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 4, 2001)]
[Graphical comparison of cycles 10, 13, 17, 20 and 23 (last update June 4, 2001)]
[Historical solar and geomagnetic data charts 1954-2001 (last update April 8, 2001)]

Recent development

The geomagnetic field was quiet to active on June 4. Solar wind speed ranged between 417 and 478 km/sec.

Solar flare activity was moderate. Solar flux was 158.3, the planetary A index was 11 (3-hour K indices: 4122 3333, Boulder K indices: 3212 2312). Region 9475 developed slowly and was quiet. Region 9482 decayed and was spotless by the end of the day. Region 9484 developed slowly and may be capable of producing another minor M class flare. Region 9485 decayed slowly and could become spotless today. Region 9486 developed slowly and is a reversed polarity region, further C class flares are likely. Region 9487 was quiet and stable and may be capable of producing occasional minor M class flares. Region 9488 is fairly complex with a magnetic delta configuration. Further minor M class flares are possible. SEC/NOAA failed to number a new region which emerged near the southeast limb northeast of region 9488.

Flares and CMEs

A total of 7 C and 2 M class events were recorded on June 4. Region 9486 produced a C2.2 flare at 00:46 and a C1.4 flare at 22:04 UTC. Region 9488 was the source of an M2.4/1F flare at 08:12 and a C1.4 flare at 15:15 UTC. Spotless region 9474 generated a C3.2 flare at 16:33 UTC. A moderate type II radio sweep was recorded. A weak enhancement in the above 10 MeV proton flux was observed following this event. Region 9484 produced a C1.3 flare at 21:10 and an M1.7 flare at 22:59 UTC. There may have been a geoeffective CME associated with the M1 flare.

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

Coronal holes

A coronal hole in the northern hemisphere will rotate into a geoeffective position on June 5-6.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 5, possibly becoming more active towards the end of the day as a weak coronal stream arrives. Long distance medium wave (AM) band propagation along east-west paths over high and upper middle latitudes is poor.

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

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)

Monthly solar data

1) Running average based on the daily 20:00 UT 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 25-40% 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. Comments and suggestions are always welcome.

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