Solar Terrestrial Activity Report

Activity chart

Last major update issued on April 6, 2016 at 05:05 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 (April 2, 2016)
Solar cycle Solar cycles 23-24 (April 2, 2016) Historical solar and geomagnetic data charts 1954-2006 (April 5, 2007)
  Cycle 24 progress (April 2, 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 (April 2, 2016) 3rd SSN Workshop, Tucson, 2013
  Comparison of cycles 12, 13, 14, 16 and 24 (April 2, 2016) 4th SSN Workshop, Locarno, 2014
  Solar polar fields vs. solar cycles (March 12, 2016)  

Recent activity

The geomagnetic field was quiet on April 5. Solar wind speed at SOHO ranged between 348 and 441 km/s.

Solar flux at 20h UTC on 2.8 GHz was 83.4 (decreasing 14.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 96.5. The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 11012121 (planetary), 01212222 (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 5 active regions using 2K resolution (SN: 83) and 4 active regions using 1K resolution (SN: 56) SDO images on the visible solar disk.

Region 12526 [S03W87] decayed slowly and quietly.
Region 12527 [N15W42] decayed slowly and quietly.
Region 12528 [N07W22] developed as new flux emerged in the trailing spot section. The region has polarity intermixing and could produce C flares.

Spotted regions not numbered (or interpreted differently) by SWPC:
S5217 [N15W07] was quiet and stable.
New region S5220 [S08W34] emerged with a tiny spot.

C2+ flares:

Magnitude Peak time (UT) Location AR Recorded by Comment
           

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

Coronal mass ejections (CMEs)

April 3-5: 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 decaying southern hemisphere coronal hole rotated across the central meridian on April 3-4, it is probably too far to the south to cause geomagnetic effects.

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 to fair.

Forecast

The geomagnetic field is expected to be quiet on April 6-8.

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
12526 2016.03.23
2016.03.24
1 1 1 S03W89 0120 HSX HSX

location: S03W87

S5210 2016.03.29       N03W48            
12528 2016.03.31
2016.04.03
4 23 13 N07W23 0030 CRO DAC

area: 0150

S5214 2016.04.01       S26W25            
S5215 2016.04.02       S42W11            
12527 2016.04.03   2   N14W44 0004   AXX  
S5217 2016.04.03   6 1 N15W07 0012   BXO images/AR_S5217_20160405_2345.png  
S5218 2016.04.04       N08W38          
S5220 2016.04.05   1 1 S08W34 0003   AXX    
Total spot count: 5 33 16  
Sunspot number: 25 83 56  (total spot count + 10 * number of spotted regions)
Weighted SN: 13 43 26  (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): 28 37 45 k * (sunspot number)
As of February 19, 2015: 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
2015.02 129.1 126.0 66.7 86.1 (-3.2) 9.92
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 (64.6 projected, -1.4) 14.02
2015.11 109.3 106.9 63.2 (61.9 projected, -2.7) 12.09
2015.12 113.1 109.5 57.7 (59.9 projected, -2.0) 14.29
2016.01 103.4 100.1 56.6 (58.2 projected, -1.7) 9.4
2016.02 103.6 101.0 57.2 (55.9 projected, -2.3) 9.9
2016.03 91.5 90.6 54.9 (52.9 projected, -3.0) 10.0
2016.04 (82.5)   3.6 (2A) / 21.6 (2B) / 40.3 (2C) (50.2 projected, -2.7) (8.2)

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.