Solar Terrestrial Activity Report

Activity chart

Last major update issued on February 21, 2015 at 04:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update February 1, 2015)] [Cycle 24 progress (last update February 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update February 1, 2015)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update February 1, 2015)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update February 1, 2015)]

[Noon SDO sunspot count 1K Reference: 4K (large file) (updated daily)]

[POES auroral activity level October 2009 - December 2012]
[Solar polar fields vs solar cycles - updated February 21, 2015]
[Presentations: 3rd SSN Workshop, Tucson, 2013 (pdf) / 4th SSN Workshop, Locarno, 2014]

Recent activity

The geomagnetic field was quiet on February 20. Solar wind speed at SOHO ranged between 311 and 361 km/s.

Solar flux at 20h UTC on 2.8 GHz was 119.7 (decreasing 5.6 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 144.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.4). Three hour interval K indices: 12212112 (planetary), 12222212 (Boulder).

The background x-ray flux is at the class B4 level.

At the time of counting spots (see image time), spots were observed in 11 active regions using 2K resolution (SN: 170) and 8 active regions using 1K resolution (SN: 114) SDO images on the visible solar disk.

Region 12287 [N14W03] decayed slowly and quietly.
Region 12288 [S07W68] decayed slowly and quietly.
Region 12289 [S09E47] was quiet and stable.
Region 12290 [N19E46] was quiet and stable.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4224 [S21W12] reemerged with a penumbra spot.
S4227 [N17E28] reemerged with penumbra spots.
S4231 [N10E11] reemerged with penumbra spots.
New region S4236 [S18E08] was observed with penumbra spots.
New region S4237 [N17W11] emerged with a penumbra spot.
New region S4238 [S19W27] emerged with a penumbra spot.

C2+ flares (GOES):

Magnitude Peak time (UTC) Location AR Comment
C2.3 (LDE) 15:22 undetermined    

Coronal mass ejections (CMEs)

February 18-20: No obviously Earth directed CMEs were observed in LASCO 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 southern hemisphere coronal hole (CH655) was in an Earth facing position on February 19-21. A small coronal hole (CH656) in the northern hemisphere could rotate across the central meridian on February 22.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on February 21. A coronal hole related disturbance could start on February 22 and cause unsettled intervals until February 24.

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: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% 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 Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12288 2015.02.12
2015.02.18
4 12 6 S08W66 0040 CAO DAO beta-gamma

area: 0080

12284 2015.02.12
2015.02.13
  1 1 N14W37 0004   AXX    
S4221 2015.02.13       S17W14            
S4222 2015.02.14       S06W48            
12285 2015.02.14
2015.02.15
      S08W85            
S4224 2015.02.15   1   S21W12 0003   AXX    
S4226 2015.02.16       N13W48            
S4227 2015.02.17   2 1 N17E28 0006   BXO    
12287 2015.02.17
2015.02.18
5 16 12 N14W04 0030 CRI DRI area: 0060
12289 2015.02.17
2015.02.18
1 6 2 S07E43 0010 AXX CRO location: S09E47

area: 0015

S4231 2015.02.17   4 3 N10E11 0010   BXO    
12290 2015.02.18 3 14 8 N19E43 0020 DRI DRI location: N19E46
S4232 2015.02.18       S09E27            
S4234 2015.02.18       N18E12            
S4236 2015.02.20   2 1 S18E08 0006   AXX    
S4237 2015.02.20   1   N17W11 0003   AXX    
S4238 2015.02.20   1   S19W27 0002   AXX  

 

Total spot count: 13 60 34  
Sunspot number: 53 170 114  (total spot count + 10 * number of spotted regions)
Weighted SN: 24 74 48  (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 60 63 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO)
Smoothed sunspot number Average ap
(3)
Measured 1 AU
2013.09 102.6 103.7 36.9 73.1 (+4.1) 5.23
2013.10  132.1 131.2 85.6 75.0 (+1.9) 7.71
2013.11  148.3 145.1 77.6 75.4 (+0.4) 5.68
2013.12 147.7 143.1 90.3 76.0 (+0.6) 4.68
2014.01 157.4 152.4 81.8 77.3 (+1.3) 5.44
2014.02 170.3
(cycle peak)
166.3 102.3 (cycle peak) 78.4 (+1.1) 10.70
2014.03 149.9 148.5 91.9 80.8 (+2.4) 4.88
2014.04 143.9 144.8 84.7 81.9 (+1.1)
(likely solar max)
7.88
2014.05 129.7 132.9 75.2 80.5 (-1.4) 5.75
2014.06 122.0 125.8 71.0 79.7 (-0.8) 6.72
2014.07 137.4 141.8 72.5 78.6 (-1.1) 4.50
2014.08 124.7 127.9 74.7 (76.2 projected, -2.4) 7.71
2014.09 146.6 148.1 87.6 (73.0 projected, -3.2) 9.78
2014.10 153.4 152.9 60.6 (70.5 projected, -2.5) 8.96
2014.11 154.8 151.4 70.1 (68.8 projected, -1.7) 9.33
2014.12 158.7 153.8 78.0 (67.7 projected, -1.1) 11.24
2015.01 141.9 137.3 67.0 (66.5 projected, -1.2) 9.46
2015.02 134.3 (1)   54.9 (2A) / 76.9 (2B) / 76.4 (2C) (64.9 projected, -1.6) (9.5)

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 WDC-SILSO 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 GFZ Potsdam WDC ap indices.

This report has been prepared by Jan Alvestad. It is based on the 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.