Solar Terrestrial Activity Report

Last major update issued on July 6, 2007 at 04:00 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 5. Solar wind speed ranged between 386 and 547 km/s (average speed was 472 km/s, decreasing 90 km/s from the previous day).

Solar flux measured at 20h UTC on 2.8 GHz was 71.7. The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 11212112 (planetary), 11211212 (Boulder).

The background x-ray flux is below the class A1 level.

At midnight there was 1 spotted region on the visible solar disk. The solar flare activity level was very low. No C class events were recorded during the day.

Region 10961 was quiet and stable.

Coronal mass ejections (CMEs)

July 3-5: 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 (CH277) in the southern hemisphere will likely be in an Earth facing position on July 7.

.

Processed SOHO/EIT 195 image at 19:25 UTC on July 5. 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. Propagation on long distance northeast-southwest paths is fair to good.

Monitoring remarks from a location near N58E06: July 6: A number of stations from Brazil, Argentina, Uruguay and Paraguay were heard on a new EWE aimed southwest. The best signal was that of 1270 kHz Radio Provincia Buenos Aires. From North America only a few stations were audible with 1510 WWZN delivering the strongest signal.

Forecast

The geomagnetic field is expected to be quiet on July 6-9. CH277 could cause some unsettled and active intervals on July 10-11.

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 3 3 S08W57 0060 HSX classification was HAX at midnight
10962 2007.06.28 1   S05W25 0060 AXX spotless
Total spot count: 4 3  
SSN: 24 13  

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 72.5 (1) 3.0 (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]