Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 21, 2015 at 04:40 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 (July 3, 2015)
Solar cycle Solar cycles 23-24 (July 1, 2015) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (July 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 (July 1, 2015) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (July 1, 2015) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs solar cycles (July 18, 2015)  

Recent activity

The geomagnetic field was very quiet on July 20. Solar wind speed at SOHO ranged between 274 and 315 km/s. Solar wind density increased during the day and a weak low speed stream arrived late in the day at ACE, likely associated with CH677.

Solar flux at 20h UTC on 2.8 GHz was 93.2 (decreasing 22.9 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 122.5. The Potsdam WDC planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.8). Three hour interval K indices: 00111011 (planetary), 11132322 (Boulder).

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

At the time of counting spots (see image time), spots were observed in 2 active regions using 2K resolution (SN: 74) and 2 active regions using 1K resolution (SN: 47) SDO images on the visible solar disk.

Region 12386 [N11W32] was quiet and stable.
Region 12387 [N17E08] lost mature penumbra and gained small spots.

C2+ flares:

Magnitude Peak time (UTC) Location AR Recorded by Comment
           

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

(SDO/EVE data currently unavailable, chart will be updated when data is online)

Coronal mass ejections (CMEs)

July 18, 20: No obviously Earth directed CMEs were observed.
July 19: A CME associated with a C2 long duration event and an erupting filament in the southwest quadrant may have had a weak Earth directed component. If that is the case weak CME effects could be observed late on July 22 and on July 23.

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 small trans equatorial coronal hole (CH677) was in an Earth facing position on July 16-17.

Propagation

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

Forecast

The geomagnetic field is expected to be quiet on July 21-23 with a chance of unsettled intervals on July 21 due to weak effects from CH677.

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
12386 2015.07.11
2015.07.12
1 20 9 N11W34 0040 HSX CAO area: 0070
12387 2015.07.15
2015.07.16
18 34 18 N17E04 0120 DAI DRI location: N17E08
S4620 2015.07.15       N18W44          
S4621 2015.07.16       S20W09            
S4623 2015.07.17       S09E02            
S4624 2015.07.17       N11E24            
S4627 2015.07.19       S19W35          
S4629 2015.07.19       N25W01          
Total spot count: 19 54 27  
Sunspot number: 39 74 47  (total spot count + 10 * number of spotted regions)
Weighted SN: 29 64 37  (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): 43 41 40 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
2014.01 157.4 152.4 117.0 109.3 (+1.7) 5.44
2014.02 170.3
(cycle peak)
166.3 146.1 (cycle peak) 110.5 (+1.2) 10.70
2014.03 149.9 148.5 128.7 114.3 (+3.8) 4.88
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
2014.07 137.4 141.8 100.2 112.8 (-1.3) 4.50
2014.08 124.7 127.9 106.9 108.7 (-4.1) 7.71
2014.09 146.6 148.1 130.0 102.5 (-6.2) 9.78
2014.10 153.4 152.9 90.0 98.0 (-4.5) 8.96
2014.11 154.8 151.4 103.6 95.7 (-2.3) 9.33
2014.12 158.7 153.8 112.9 93.3 (-2.4) 11.24
2015.01 141.9 137.3 97.6 (91.1 projected, -2.2) 9.46
2015.02 129.1 126.0 67.8 (89.8 projected, -1.3) 9.92
2015.03 125.9 124.6 56.8 (87.3 projected, -2.5) 16.14
2015.04 128.8 129.7 78.0 (83.9 projected, -3.4) 10.73
2015.05 120.0 122.6 90.0 (81.3 projected, -2.6) 8.29
2015.06 122.3 126.1 68.3 (78.0 projected, -3.3) 12.8
2015.07 (113.1)   50.4 (2A) / 78.1 (2B) / 79.1 (2C) (74.4 projected, -3.6) (8.5)

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).
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.