Solar Terrestrial Activity Report

Activity chart

Last major update issued on May 3, 2016 at 03:30 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 (May 1, 2016)
Solar cycle Solar cycles 23-24 (May 1, 2016) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (May 1, 2016) Noon SDO sunspot count 1K / 4K (*)
  Solar cycles 1-24 (July 17, 2015) POES auroral activity level October 2009 - December 2012
  Comparison of cycles 21, 22, 23 and 24 (May 1, 2016) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (May 1, 2016) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (April 20, 2016)  

Recent activity

The geomagnetic field was quiet to minor storm on May 2 under the influence of effects from CH730. Solar wind speed at SOHO ranged between 442 and 562 km/s.

Solar flux at 20h UTC on 2.8 GHz was 89.8 (increasing 6.4 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 94.9. The Potsdam WDC planetary A index was 26 (STAR Ap - based on the mean of three hour interval ap indices: 26.4). Three hour interval K indices: 55223345 (planetary), 55333344 (Boulder).

The background x-ray flux is at the class B2 level.

At the time of counting spots (see image time), spots were observed in 6 active regions using 2K resolution (SN: 103) and 6 active regions using 1K resolution (SN: 90) SDO images on the visible solar disk.

Region 12535 [N08W41] decayed slowly and quietly.
Region 12536 [N15W25] decayed slowly as the main penumbrae fragmented.
Region 12539 [N16E09] developed slightly as new negative flux emerged near the easternmost positive polarity spot.
New region 12541 [N04E68] rotated into view on May 1 and was numbered the next day.

Spotted regions not numbered (or interpreted differently) by SWPC:
S5263 [N06W24] reemerged with small spots.
S5264 [N03W60] was quiet and stable.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
C3.5 08:42   12540 GOES15 fast type II radio sweep

CME off the east limb, no obviously Earth directed components observed

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

Coronal mass ejections (CMEs)

April 30 - May 2: 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 poorly defined trans equatorial coronal hole (CH732) will be in an Earth facing position on May 3. Another trans equatorial coronal hole (CH733) will likely be Earth facing on May 5.

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 fair.

Forecast

The geomagnetic field is expected to be quiet to active on May 3 due to effects from CH730 and quiet to unsettled on May 4 becoming quiet on May 5. May 6-7 could see quiet to active conditions due to effects from CH732.

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). 4K 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
S5247 2016.04.22       N17W38            
12534 2016.04.24       N11W63           location: N06W57
12535 2016.04.24 3 3 3 N07W42 0030 CAO HAX  
S5254 2016.04.24       N01W42            
12536 2016.04.25
2016.04.26
9 17 11 N16W26 0090 DAO DAO  
12538 2016.04.26
2016.04.27
      S04W38            
S5258 2016.04.26       S18W55            
12539 2016.04.27
2016.04.28
7 15 10 N16E07 0070 EAI EAI beta-gamma-delta
S5261 2016.04.28       S10W26            
12540 2016.04.29
2016.04.30
3     N22E24 0010 BXO     spotless
S5263 2016.04.30   2 2 N06W24 0010 AXX      
S5264 2016.04.30   1 1 N03W60 0003   BXO  
12541 2016.05.01
2016.05.02
3 5 3 N04E64 0010 BXO BXO location: N04E68
Total spot count: 25 43 30  
Sunspot number: 75 103 90  (total spot count + 10 * number of spotted regions)
Weighted SN: 40 58 45  (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): 83 46 72 k * (sunspot number)
As of February 19, 2016: k = 1.1 for SWPC, k = 0.45 for MSN 2K, k = 0.80 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
2015.03 125.9 124.6 54.5 82.2 (-3.9) 16.14
2015.04 128.8 129.7 75.3 78.9 (-3.3) 10.73
2015.05 120.0 122.6 88.8 76.1 (-2.8) 8.29
2015.06 122.3 126.1 66.5 72.1 (-4.0) 13.15
2015.07 107.0 110.8 66.4 68.3 (-3.8) 8.83
2015.08 105.4 108.0 64.6 66.4 (-1.9) 14.58
2015.09 101.7 102.7 78.1 66.0 (-0.4) 15.78
2015.10 104.1 103.3 61.7 64.4 (-1.6) 14.02
2015.11 109.3 106.9 63.2 (61.2 projected, -3.2) 12.09
2015.12 113.1 109.5 57.7 (58.8 projected, -2.4) 14.29
2016.01 103.4 100.1 56.6 (57.1 projected, -1.7) 9.4
2016.02 103.6 101.0 57.2 (54.8 projected, -2.3) 9.9
2016.03 91.5 90.6 54.9 (51.9 projected, -2.9) 10.58
2016.04 93.3 94.0 38.0 (49.1 projected, -2.8) 8.7
2016.05 (91.0)   4.9 (2A) / 76 (2B) / 49.6 (2C) (47.2 projected, -1.9) (20.4)

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.