Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 23, 2013 at 06:30 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update March 1, 2013)] [Cycle 24 progress (last update March 2, 2013) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 1, 2013)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 1, 2013)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2013)]

[POES auroral activity level since October 2009 - updated January 26, 2013]
[Solar polar fields vs solar cycles - updated February 3, 2013]
[Presentation 3rd SSN Workshop, Tucson, 2013 (pdf)]

Recent activity

The geomagnetic field was quiet on March 22. Solar wind speed at SOHO ranged between 379 and 440 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 100.9 (increasing 6.0 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.0). Three hour interval K indices: 11111122 (planetary), 00011221 (Boulder).

The background x-ray flux was at the class B3 level.

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11695 [N09W76] was quiet and stable.
Region 11700 [S16W11] lost the trailing spots and gained leading penumbra spots.
Region 11702 [N08W36] developed slowly and quietly.
New region 11703 [S24W59] emerged on March 19 and was numbered by SWPC 3 days later. The region developed significantly on March 22.

Spotted regions not numbered by SWPC:
S2299 [N22W18] was quiet and stable.
New region S2310 [S21E40] emerged with trailing spots in an old plage area.
New region S2311 [S08W06] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

March 20-22: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

Coronal holes

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

A poorly defined trans equatorial coronal hole in the eastern hemisphere will likely be numbered within the next day.

Coronal hole map

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 23-25.

Coronal holes (1) Coronal mass ejection (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

(Click on image for 2K resolution) Compare to the previous day's image. 0.5k image

When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.

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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
11695 2013.03.10
2013.03.11
3 3 2 N10W79 0100 CAO HAX

location: N09W76

S2292 2013.03.15       S27W39           plage
11700 2013.03.15
2013.03.17
  2   S13W15 0005   AXX

location: S16W12

S2294 2013.03.15       N14W48           plage
S2299 2013.03.15   1   N18W11 0002   AXX  
S2301 2013.03.17       S13W27           plage
S2305 2013.03.18       N07W46           plage
11703 2013.03.19
2013.03.22
5 12 6 S25W59 0040 DAO DAO area: 0090
11701 2013.03.20 2     N14W87 0030 HRX       AR 11694, rotated out of view
11702 2013.03.20
2013.03.21
4 13 6 N08W38 0040 DAO DRO area: 0080
S2309 2013.03.21       N00W10         plage
S2310 2013.03.22   2 1 S21E40 0008   AXX    
S2311 2013.03.22   1   S08E06 0002   AXX    
Total spot count: 14 34 15  
Sunspot number: 54 104 55  (total spot count + 10 * number of spotted regions)
Weighted SN: 32 47 28  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 32 36 30 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2011.11 153.5 (cycle max) 96.7 (cycle max) 61.1 (+1.2) 5.55
2011.12 141.3 73.0 63.4 (+2.3) 3.78
2012.01 132.5 58.3 65.5 (+2.1) 7.15
2012.02 106.5 32.9 66.9 (+1.4)
possible cycle 24 max
8.81
2012.03 114.7 64.3 66.8 (-0.1) 16.08
2012.04 113.0 55.2 64.6 (-2.2) 10.10
2012.05 121.5 69.0 61.7 (-2.9) 7.06
2012.06 119.6 64.5 58.9 (-2.8) 10.08
2012.07 133.9 66.5 57.7 (-1.2) 13.90
2012.08 115.4 63.0 58.1 (+0.4) 7.96
2012.09 122.9 61.4 (57.9 projected, -0.2) 8.07
2012.10 123.3 53.3 (57.0 projected, -0.9) 9.97
2012.11 121.3 61.4 (56.1 projected, -0.9) 7.08
2012.12 108.6 40.8 (54.9 projected, -1.2) 3.44
2013.01 127.1 62.9 (53.6 projected, -1.3) 4.69
2013.02 104.3 38.0 (52.5 projected, -1.1) 6.11
2013.03 116.0 (1) 64.7 (2A) / 91.2 (2B) / 51.3 (2C) (51.5 projected, -1.0) (9.85)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The official SIDC international sunspot number is typically 30-50% lower. 2B) Boulder SN current month average to date. 2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC ap indices.

This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.

SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.