Solar Terrestrial Activity Report

Last major update issued on July 7, 2007 at 02:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update June 3, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update June 3, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update June 3, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update July 1, 2007)]

Recent activity

The geomagnetic field was quiet on July 7. Solar wind speed ranged between 439 and 463 km/s (average speed was 448 km/s, increasing 3 km/s over the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 73.1. The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.8). Three hour interval K indices: 21111222 (planetary), 22111222 (Boulder).

The background x-ray flux is at the class A8 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was low. A single C class event was recorded during the day.

New region 10963 rotated into view at the southeast limb. This region is fairly active and could produce further C flares. Flare: C1.9 at 14:30 UTC.

Coronal mass ejections (CMEs)

July 5-7: No obvious fully or partially Earth directed CMEs were observed in incomplete 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 (CH277) in the southern hemisphere was in an Earth facing position on July 6-7.

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Processed STEREO 195 image at 23:25 UTC on July 7. The darkest areas on the solar disk are likely coronal holes.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along east-west paths over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.

Monitoring remarks from a location near N58E06: July 8: A few stations from Newfoundland and the northeastern US were audible at 02h UTC, 1510 WWZN had a fairly good signal.

Forecast

The geomagnetic field is expected to be quiet on July 8-9. CH277 could cause some unsettled and active intervals late on July 9 and on July 10.

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.

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
10961 2007.06.25 2   S08W86 0060 HSX rotated out of view
10962 2007.06.28     S05W51     plage
10963 2007.07.07 1 4 S09E83 0050 AXX classification was DAO at midnight, area 0100
Total spot count: 3 4  
SSN: 23 14  

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)
2006.05 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 (-0.6)
2007.01 83.3 16.9 (11.9 predicted, -0.2)
2007.02 77.7 10.6 (11.3 predicted, -0.6)
2007.03 72.2 4.8 (10.8 predicted, -0.5)
2007.04 72.4 3.7 (10.8 predicted, unchanged)
2007.05 74.4 11.7 (10.6 predicted, -0.2)
2007.06 73.7 12.0 (10.7 predicted, +0.1)
2007.07 72.4 (1) 4.1 (2) (11.0 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]