Solar Terrestrial Activity Report

Last major update issued on March 21, 2010 at 05:55 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-23 (last update October 4, 2007)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22 and 23 (last update October 4, 2007)]
[Graphical comparison of cycles 2, 10, 13, 17, 20 and 23 (last update October 4, 2007)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports (last update January 3, 2010)]

Recent activity

The geomagnetic field was quiet to unsettled on March 20. Solar wind speed ranged between 351 and 402 km/s under the influence of a coronal hole stream.

Solar flux measured at 20h UTC on 2.8 GHz was 83.5. The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 6.8). Three hour interval K indices: 13312121 (planetary), 13412221 (Boulder).

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

At midnight there was 1 spotted region on the visible solar disk.

Region 11056 reemerged with many spots and could produce C flares.

Coronal mass ejections (CMEs)

March 18-20: No obvious Earth directed CMEs were observed in LASCO or STEREO images.

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

No obvious coronal holes are currently in or near Earth facing positions.

Processed SOHO/EIT 195 image at 23:48 UTC on March 20. The darkest areas on the solar disk are likely coronal holes.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on March 21-24.

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/SWPC. 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 SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.

Active region Date numbered SWPC
spot
count
STAR
spot
count
Location at midnight Area SWPC
Classification
Comment
11054 2010.03.10 1   N16W82 0010 AXX rotated out of view
11056 2010.03.17 4 17 N18E07 0030 BXO classification was DAI at midnight, area 0050
Total spot count: 5 17  
SSN: 25 27  

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
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)  
2008.07 65.7 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
2009.01 69.8 1.3 1.8 (+0.1) 3.70
2009.02 70.0 1.4 1.9 (+0.1) 4.68
2009.03 69.2 0.7 2.0 (+0.1) 4.85
2009.04 69.7 1.2 2.2 (+0.2) 4.52
2009.05 70.5 2.9 2.3 (+0.1) 4.75
2009.06 68.6 2.6 2.7 (+0.4) 5.22
2009.07 68.2 3.5 3.6 (+0.9) 5.49 / 4.55
2009.08 67.3 0.0 4.8 (+1.2) 5.70 / 4.89
2009.09 70.5 4.2 (6.4 predicted, +1.6) 3.88 / 3.61
2009.10 72.6 4.6 (8.3 predicted, +1.9) 3.66 / 3.56
2009.11 73.6 4.2 (10.3 predicted, +2.0) 2.45 / 2.63
2009.12 76.7 10.6 (12.4 predicted, +2.1) 1.41 / 1.92
2010.01 81.1 13.1 (15.0 predicted, +2.6) 2.93 / 3.07
2010.02 84.7 18.6 (17.9 predicted, +2.9) 4.15 / 4.61
2010.03 82.7 (1) 15.6 (2) (21.1 predicted, +3.2) (5.03)

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/SWPC) sunspot number. The official international sunspot number is typically 30-50% lower.
3) Running average based on the daily SWPC ap indices. Values in red are based on official NGDC ap indices.

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.