Solar Terrestrial Activity Report

Activity chart

Last major update issued on March 4, 2013 at 05:05 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 to unsettled on March 3. Solar wind speed at SOHO ranged between 373 and 512 km/s under the influence of a high speed stream from CH556.

Solar flux measured at 20h UTC on 2.8 GHz was 112.0 (increasing 6.9 over the last solar rotation). The Potsdam WDC planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.6). Three hour interval K indices: 33221112 (planetary), 33221311 (Boulder).

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

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11680 [S29W40] decayed slowly and could soon become spotless.
Region 11681 [N15W16] decayed slowly and quietly.
Region 11682 [S19W70] decayed slowly and quietly.
Region 11683 [S16E28] decayed slowly and quietly.
Region 11685 [S16E48] decayed slowly and quietly.
New region 11686 [S13W32] was first observed with spots on February 26, then became spotless before reemerging with many spots on March 2. SWPC / USAF numbered the region on March 3.
New region 11687 [N08E69] rotated partly into view on March 2 and was numbered the next day by SWPC.

Spotted regions not numbered by SWPC:
S2264 [S18E12] was quiet and stable.
S2266 [N09W19] gained a leading polarity spot.
New region S2267 [S18E79] rotated into view.
New region S2268 [S33E15] emerged with a penumbra spot.

Coronal mass ejections (CMEs)

March 1-3: 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 northern hemisphere coronal hole (CH557) was in a geoeffective position on March 1. A southern hemisphere coronal hole (CH558) was in an Earth facing position on March 3.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on March 4-5 due to effects from CH557. Another disturbance, associated with CH558, could start on March 6.

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
11682 2013.02.21
2013.02.25
2 4 3 S18W68 0200 DAO DSO

 

11680 2013.02.24
2013.02.25
  1   S28W41 0002   AXX  
11681 2013.02.24
2013.02.25
2 13 1 N17W21 0010 AXX BXO area: 0025

location: N15W16

S2253 2013.02.24       N41W46           plage
S2255 2013.02.25       S28W50           plage
11686 2013.02.26
2013.03.03
6 15 7 S13W31 0030 DRO DRI  
11683 2013.02.27 14 21 10 S16E30 0200 EAI CAI  

 

S2261 2013.02.27       S10W03           plage
11685 2013.02.28
2013.03.01
3 5 3 S15E46 0020 DRO DRO location: S16E48
11684 2013.03.01 4     N17W15 0010 BXO       part of AR 11681, interpretational error by SWPC
S2264 2013.03.01   1   S18E12 0002   AXX  
11687 2013.03.02
2013.03.03
3 4 2 N06E65 0030 CRO CRO location: N08E69
S2266 2013.03.02   2   N09W19 0004   BXO  
11688 2013.03.03 1     S17E52 0020 HSX       SWPC apparently has counted the trailing spot of AR 11685 twice
S2267 2013.03.03   2 2 S18E79 0030   AXX    
S2268 2013.03.03   1   S33E15 0002   AXX    
Total spot count: 35 69 28  
Sunspot number: 115 179 98  (total spot count + 10 * number of spotted regions)
Weighted SN: 59 88 47  (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): 69 63 54 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) 5.48
2013.03 111.9 (1) 9.5 (2A) / 97.7 (2B) / 42.5 (2C) (51.5 projected, -1.0) (17.79)

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.