Last major update issued on April 22, 2015 at 05:05 UT
[Solar and geomagnetic
data - last month (updated daily)]
[Solar wind and
electron fluence charts (updated daily)]
[Solar cycles 23-24 (last update April 1,
2015)] [Cycle 24
progress (last update April 1, 2015) ]
[Solar cycles 1-20]
[Graphical comparison of cycles
21, 22, 23 and 24 (last update April 1, 2015)]
[Graphical comparison of cycles
10, 12, 13, 14, 16 and 24 (last update April 1, 2015)]
[Historical solar and geomagnetic
data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since
January 2003 (last update April 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 April 10, 2015]
[Presentations:
3rd SSN Workshop, Tucson, 2013 (pdf)
/
4th SSN Workshop, Locarno, 2014]
The geomagnetic field was quiet to active on April 21 under the influence of a high speed stream from CH664. Solar wind speed at SOHO ranged between 522 and 601 km/s.
Solar flux at 20h UTC on 2.8 GHz was 153.8 (increasing 16.0 over the last solar rotation). The 90 day 10.7 flux at 1 AU was 128.6. The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 18.6). Three hour interval K indices: 43344323 (planetary), 33334423 (Boulder).
The background x-ray flux is at the class C1 level.
At the time of counting spots (see image time), spots were observed in 19 active regions using 2K resolution (SN: 357) and 15 active regions using 1K resolution (SN: 224) SDO images on the visible solar disk.
Region 12321 [N13W66] decayed slowly and quietly.
Region 12324 [N19W32] was quiet and stable.
Region 12325 [N04W24] developed slowly and was mostly quiet.
Region 12326 [N13W56] was quiet and stable.
Region 12327 [S09E18] was quiet and stable.
Region 12329 [S08W77] developed in the leading spot section while decay
was observed in the trialing spots.
Region 12330 [N15E18] decayed slowly and quietly.
New region 12331 [S10E09] rotated into view on
April 17 and was numbered by SWPC four days later as new flux emerged.
New region 12332 [S13W16] was first observed with spots on April 18. New
flux emerged on April 21 when the region received its NOAA number.
Spotted regions not numbered (or interpreted
differently) by SWPC:
S4367 [N08W57] decayed slowly and quietly.
S4380 [S15W56] reemerged with a penumbra spot.
S4383 [S09W02] was quiet and stable.
S4389 [S22E27] was quiet and stable.
S4392 [N10W84] developed quickly early in the day as a compact region
with an increasingly strong magnetic delta. The region produced several M class
flares with further flaring possible today as the region is transiting the
northwest limb.
S4398 [N11E05] was quiet and stable.
S4400 [N05E27] was quiet and stable.
New region S4404 [N08E64] rotated into view with penumbra spots.
New region S4405 [N20E79] rotated into view.
New region S4406 [S11W38] emerged with penumbra spots.
| Magnitude | Peak time (UTC) | Location | AR | Recorded by | Comment |
| M1.0 | 07:21 | N09W80 | S4392 | GOES15 | |
| C2.4 | 10:02 | N09W84 | S4392 | GOES15 | |
| M2.2 | 10:40 | N20E90 | S4405 | GOES15 | CME |
| M2.2 | 11:57 | N10W84 | S4392 | GOES15 | |
| C2.1 | 15:29 | S4392 | SDO/EVE | ||
| M4.0 | 15:45 | N10W84 | S4392 | GOES15 | |
| M2.1 | 17:00 | N13W84 | S4392 | GOES13 | |
| C3.1 | 20:22 | S4392 | SDO/EVE | ||
| C5.0/2F | 20:59 | N03W18 | 12325 | GOES15 | |
| M1.8 | 21:45 | S4392 | GOES15 | ||
| M1.2 | 22:01 | S4392 | GOES15 | attributed to AR 12325 by SWPC |
April 19-21: No obviously Earth directed CMEs were observed.
[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 (CH664) rotated across the central meridian on April 16-18.
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.
The geomagnetic field is expected to be quiet to unsettled on April 22-24.
| 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.
(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 | ||||||||||
| 12322 | 2015.04.10 2015.04.11 |
10 | N11W87 | 0060 | DAC |
spotless location: N13W93 SWPC has moved AR 12322 to the location of AR S4392 |
|||||
| 12321 | 2015.04.10 2015.04.11 |
1 | 1 | N07W58 | 0030 | HSX | AXX |
 |
 |
area: 0001 location: N13W66 SWPC data is for AR S4367 |
|
| S4367 | 2015.04.11 | 1 | 1 | N08W57 | 0050 | HAX |
 |
 |
|||
| 12326 | 2015.04.11 2015.04.16 |
3 | 1 | N15W55 | 0010 | HRX |
 |
 |
location: N13W56 | ||
| 12324 | 2015.04.13 2015.04.14 |
16 | 29 | 15 | N19W33 | 0170 | CAI | CAI |
 |
 |
|
| 12325 | 2015.04.13 2015.04.14 |
8 | 39 | 15 | N06W24 | 0210 | DAO | DKI |
 |
 |
area: 0360 location: N04W24 |
| S4380 | 2015.04.15 | 1 | S15W56 | 0002 | AXX |
 |
|||||
| S4381 | 2015.04.15 | N18W49 | |||||||||
| S4383 | 2015.04.16 | 9 | 6 | S09W02 | 0025 | BXO |
 |
 |
|||
| 12327 | 2015.04.16 2015.04.17 |
3 | 21 | 9 | S10E17 | 0090 | HSX | CSO |
 |
 |
area: 0170 |
| S4385 | 2015.04.16 | S18W58 | |||||||||
| S4389 | 2015.04.17 | 4 | S22E27 | 0010 | BXO |
 |
 |
||||
| 12331 | 2015.04.17 2015.04.21 |
10 | 23 | 10 | S10E10 | 0030 | BXI | DAI |
 |
 |
area: 0140 |
| 12329 | 2015.04.17 2015.04.19 |
9 | 9 | 5 | S08W79 | 0050 | CRO | CAO |
 |
 |
area: 0100 |
| S4392 | 2015.04.17 | 1 | 1 | N10W84 | 0190 | HAX |
 |
 |
|||
| 12332 | 2015.04.18 2015.04.21 |
2 | 8 | 5 | S13W17 | 0010 | BXO | DRO |
 |
 |
area: 0030 |
| 12330 | 2015.04.19 2015.04.20 |
4 | 5 | N15E18 | 0020 | CSO | BXO |
 |
 |
||
| S4398 | 2015.04.19 | 2 | 1 | N11E05 | 0006 | BXO |
 |
 |
|||
| S4400 | 2015.04.20 | 6 | 1 | N05E27 | 0003 | BXO | images/AR_S4400_20150421_2345.png |
 |
|||
| S4401 | 2015.04.20 | N20W53 |
 |
||||||||
| S4404 | 2015.04.21 | 2 | 2 | N08E64 | 0010 | BXO |
 |
||||
| S4405 | 2015.04.21 | 1 | 1 | N20E79 | 0090 | HAX |
 |
||||
| S4406 | 2015.04.21 | 2 | 1 | S11W38 | 0005 | BXO |
 |
||||
| Total spot count: | 63 | 167 | 74 | ||||||||
| Sunspot number: | 153 | 357 | 224 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 96 | 218 | 125 | (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): | 92 | 125 | 123 | k * (sunspot number). k = 0.6 for SWPC, k = 0.35 for MSN 2K, k = 0.55 for MSN 1K (MSN=Magnetic Sunspot Number) | |||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number | Average
ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 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 | 75.6 (-3.0) | 7.71 |
| 2014.09 | 146.6 | 148.1 | 87.6 | 70.9 (-4.7) | 9.78 |
| 2014.10 | 153.4 | 152.9 | 60.6 | (67.3 projected, -3.6) | 8.96 |
| 2014.11 | 154.8 | 151.4 | 70.1 | (64.7 projected, -2.6) | 9.33 |
| 2014.12 | 158.7 | 153.8 | 78.0 | (62.4 projected, -2.3) | 11.24 |
| 2015.01 | 141.9 | 137.3 | 67.0 | (60.2 projected, -2.2) | 9.46 |
| 2015.02 | 129.1 | 126.0 | 44.8 | (58.4 projected, -1.8) | 9.92 |
| 2015.03 | 125.9 | 124.6 | 38.4 | (56.1 projected, -2.3) | 16.14 |
| 2015.04 | (132.0) | 53.0 (2A) / 75.7 (2B) / 84.2 (2C) | (53.4 projected, -2.7) | (12.2) | |
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). 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.
