Solar Terrestrial Activity Report

Activity chart

Last major update issued on September 24, 2015 at 04:45 UT.

Charts (* = updated daily) Data and archive
  Solar wind (*) Solar and geomagnetic data - last month (*)
  Electron fluence (*) Archived daily reports and monthly data from 2003.01 (September 1, 2015)
Solar cycle Solar cycles 23-24 (September 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (September 1, 2015) Noon SDO sunspot count 1K Reference: 4K (large file) (*)
  Solar cycles 1-24 (July 17, 2015) POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (September 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (September 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (September 16, 2015)  

Recent activity

The geomagnetic field was quiet to active on September 23. Solar wind speed at SOHO ranged between 452 and 587 km/s.

Solar flux at 17h UTC on 2.8 GHz was 107.9 (decreasing 2.3 over the last solar rotation, the measurement at 20h UT was slightly flare enhanced by a long duration C1.1 event in AR 12422). The 90 day 10.7 flux at 1 AU was 105.6. The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.0). Three hour interval K indices: 22332431 (planetary), 12443541 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 7 active regions using 2K resolution (SN: 164) and 7 active regions using 1K resolution (SN: 113) SDO images on the visible solar disk.

Region 12418 [S15W61] decayed slowly and quietly.
Region 12420 [N10E34] decayed slowly and quietly.
Region 12421 [N15E20] decayed slowly and quietly.
Region 12422 [S20E38] developed and has polarity intermixing. The region produced a number of low level C flares during the day. Further C class flares are likely.
New region 12423 [S09W09] emerged on September 21 and was numbered by SWPC 2 days later.

Spotted regions not numbered (or interpreted differently) by SWPC:
S4766 [N20W12] was quiet and stable.
New region S4778 [S04E27] emerged with penumbra spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
C2.9 07:30   12415 GOES15  
C3.2 18:57   12422 GOES15  

Flare activity (SDO/EVE/ESP XRS-B proxy)

Coronal mass ejections (CMEs)

September 21-23: No obviously Earth directed CMEs were observed in available 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 recurrent trans equatorial coronal hole (CH691) rotated across the central meridian on September 21-22.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet to minor storm on September 24-25 due to effects from CH691 and quiet to unsettled on September 26.

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 overlays
Comment
SWPC Magnetic
(SDO)
SWPC STAR Current Previous
2K 1K
12415 2015.09.10
2015.09.11
1     S19W94 0010 BXO     rotated out of view

impossible combination of spots and classification by SWPC, classification not supported by imagery

12418 2015.09.12
2015.09.13
3 5 2 S15W62 0140 HAX CAO images/AR_12418_20150922_2345.png area: 0230
12419 2015.09.13
2015.09.15
      N13W60            
S4761 2015.09.16       N23W45            
S4766 2015.09.18   8 4 N20W12 0020   AXX images/AR_S4766_20150923_2345.png images/AR_S4766_20150922_2345.png  
S4767 2015.09.18       S27W31            
12420 2015.09.19
2015.09.20
13 41 19 N10E34 0200 EAI EAI area: 0340
12421 2015.09.20
2015.09.22
5 12 5 N16E19 0050 CAO CAO  
S4772 2015.09.20       S13W31          
S4773 2015.09.21       S18E02            
12423 2015.09.21
2015.09.23
2 5 2 S09W09 0010 BXO CRO  
12422 2015.09.22 11 16 8 S20E36 0090 DAO DAI beta-gamma

area: 0220

location: S20E38

S4776 2015.09.22       S14W17          
S4777 2015.09.22       N03W53          
S4778 2015.09.23   7 3 S04E27 0015   BXO    
Total spot count: 35 94 43  
Sunspot number: 95 164 113  (total spot count + 10 * number of spotted regions)
Weighted SN: 55 117 66  (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): 105 90 96 k * (sunspot number)
As of July 1, 2015: k = 1.1 for SWPC, k = 0.55 for MSN 2K, k = 0.85 for MSN 1K (MSN=Magnetic Sunspot Number)

Monthly solar cycle data

Month Average solar flux International sunspot number
(WDC-SILSO) (4)
Smoothed sunspot number (4) Average ap
(3)
Measured 1 AU
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 (+1.2) 10.70
2014.04 143.9 144.8 112.5 116.4 (+2.1) (solar max) 7.88
2014.05 129.7 132.9 112.5 115.0 (-1.4) 5.75
2014.06 122.0 125.8 102.9 114.1 (-0.9) 6.72
2014.07 137.4 141.8 100.2 112.6 (-1.5) 4.50
2014.08 124.7 127.9 106.9 108.3 (-4.3) 7.71
2014.09 146.6 148.1 130.0 101.9 (-6.4) 9.78
2014.10 153.4 152.9 90.0 97.4 (-4.5) 8.96
2014.11 154.8 151.4 103.6 95.0 (-2.4) 9.33
2014.12 158.7 153.8 112.9 92.6 (-2.4) 11.24
2015.01 141.9 137.3 93.0 89.8 (-2.8) 9.46
2015.02 129.1 126.0 66.7 86.6 (-3.2) 9.92
2015.03 125.9 124.6 54.5 (82.1 projected, -4.5) 16.14
2015.04 128.8 129.7 78.0 (78.0 projected, -4.1) 10.73
2015.05 120.0 122.6 90.0 (75.3 projected, -2.7) 8.29
2015.06 122.3 126.1 68.3 (71.6 projected, -3.7) 13.15
2015.07 107.0 110.8 66.4 (67.9 projected, -3.7) 8.83
2015.08 105.4 108.0 64.6 (66.7 projected, -1.2) 14.58
2015.09 (95.3)   44.4 (2A) / 58.0 (2B) / 71.9 (2C) (67.0 projected, +0.3) (19.3)

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).
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.
4) Updated to new data set from WDC-SILSO on July 1, 2015

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 Universal Time. Comments and suggestions are always welcome.

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