Solar Terrestrial Activity Report

Last major update issued on June 2, 2007 at 02:35 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update May 6, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update May 6, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update May 6, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update May 18, 2007)]

Recent activity

The geomagnetic field was quiet on June 1. Solar wind speed ranged between 334 and 361 km/s (average speed was 348 km/s, increasing 34 km/s over the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 79.4. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.1). Three hour interval K indices: 22111222 (planetary), 22122223 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight there were 3 spotted regions on the visible solar disk. The solar flare activity level was moderate. A total of 1 C and 3 M class events were recorded during the day.

Region 10958 regained a single spot.
New region 10959 emerged in the southeast quadrant.
New region 10960 rotated into view at the southeast limb. This is a complex region capable of producing further M class flares. There is a magnetic delta structure in the northern central part of the largest trailing penumbra. Polarity intermixing is evident other places in the region as well. Flares: M1.0 at 06:51, M2.8 at 14:59, M2.1 at 21:52 and C2.8 at 22:22 UTC.

Coronal mass ejections (CMEs)

May 30 - June 1: No obvious fully or partially Earth directed CMEs were observed in LASCO imagery.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole (CH271) in the southern hemisphere was in an Earth facing position on May 30-31.

Processed STEREO 195 image at 21:15 UTC on June 1. The darkest areas on the solar disk are likely coronal holes.

Forecast

The geomagnetic field is expected to be quiet to active on June 2-3 due to effects from CH271 and quiet to unsettled on June 4.

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. When the high speed stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at 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.

Propagation

Daily monitoring will not resume until a local noise problem (related to construction work on a neighboring property) has been fixed. Occasional monitoring reports will be submitted when propagation is good.

April 8, 2007: Stations from the Canadian Atlantic provinces had strong signals during the night. Some stations from the northeastern USA and from Florida did well too, in particular 1510 WWZN was impressive.

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. SEC active region numbers in the table below and in the active region map above are the historic SEC/USAF numbers.

Active region Date numbered SEC
spot
count
STAR
spot
count
Location at midnight Area Classification Comment
10958 2007.05.29 4 1 S13E22 0010 BXO classification was AXX at midnight
10959 2007.06.01 2 4 S12E49 0010 BXO classification was DSO at midnight, area 0030. Location: S10E47
10960 2007.06.01 5 15 S06E73 0320 DKI beta-gamma-delta
classification was EKI at midnight, area 0450
S703 2007.05.22     S09W54     plage
Total spot count: 11 20  
SSN: 41 50  

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)
2006.04 89.0 30.2 17.1 (-0.3)
2006.05 80.9 22.3 17.3 (+0.2)
2006.06 76.5 13.9 16.3 (-1.0)
2006.07 75.7 12.2 15.3 (-1.0)
2006.08 79.0 12.9 15.6 (+0.3)
2006.09 77.8 14.4 15.6 (+0.0)
2006.10 74.3 10.4 14.2 (-1.4)
2006.11 86.3 21.5 12.7 (-1.5)
2006.12 84.5 13.6 (12.1 predicted, -0.6)
2007.01 83.3 16.9 (11.7 predicted, -0.4)
2007.02 77.7 10.6 (11.1 predicted, -0.6)
2007.03 72.2 4.8 (10.7 predicted, -0.4)
2007.04 72.4 3.7 (10.9 predicted, +0.2)
2007.05 74.4 11.7 (11.0 predicted, +0.1)
2007.06 79.4 (1) 1.4 (2) (11.3 predicted, +0.3)

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% lower.

This report has been prepared by Jan Alvestad. It is based partly on my own observations and analysis, and partly on data from some of these solar data sources. All time references are to the UTC day. Comments and suggestions are always welcome.


[DX-Listeners' Club]