Weekly Propagation Summary – 2015 Jun 29 16:10 UTC
Here is this week’s space weather and geophysical report, issued 2015 Jun 29 0647 UTC.
Highlights of Solar and Geomagnetic Activity 22 – 28 June 2015
Solar activity was at low to high levels. The period began at high levels when Region 2371 (N13, L=302, class/area Fkc/1180 on 21 June) produced an M6/2b flare at 22/1823 UTC with an associated Castelli-U spectral burst, Type II radio sweep (1480 km/s), 1000 sfu Tenflare, and a full halo coronal mass ejection (CME) with an approximate speed of 1047 km/s. Solar activity returned to high levels again on 25 June as Region 2371 produced a long-duration M7/3b flare at 25/0816 UTC with associated Type II (2056 km/s) and Type IV radio sweeps, 3800 sfu Tenflare, and an asymmetric full halo CME with an approximate speed of 1500 km/s. Region 2371 remained relatively quiet and stable after 25 June, only producing low-level C-class flaring for the rest of the period.
A greater than 10 MeV proton event was in progress at the beginning of the period. The event began at 21/2135 UTC, likely associated with an M2/1n flare at 21/0142 UTC from Region 2371, reached a maximum flux value of 1070 pfu at 22/1900 UTC and ended 24/0705 UTC. A brief enhancement to the S3 (Strong) levels was observed due to a shock enhancement from the arrival of the 21 June CME. Another greater than 10 MeV proton event began at 26/0350 UTC in association with an M7/3b flare at 25/0816 UTC from Region 2371, reached a maximum of 22 pfu (S1-Minor) at 27/0030 UTC and ended at 27/0755 UTC.
The greater than 2 MeV electron flux at geosynchronous orbit was high levels through the period with the exception of 23 June. A maximum flux of 26,376 pfu was observed at 24/1620 UTC.
Geomagnetic field activity ranged from quiet to severe storm conditions. At 22/0451 UTC, a small shock was observed at the NASA/ACE spacecraft. Total field increased from 8 nT to 17 nT with a corresponding solar wind increase from 360 km/s to 431 km/s. The shock was associated with the arrival of the 19 June CME caused by a filament eruption in the SE quadrant observed in SDO/AIA imagery beginning at 19/0500 UTC. A geomagnetic sudden impulse (SI) of 19 nT (Guam) was observed at 22/0545 UTC. The geomagnetic field responded with unsettled to active levels. At 22/1759 UTC, another shock was observed in ACE data from the 21 June CME associated with a double peak M2 flare from Region 2371 at 21/0142 UTC. Total field increased to a maximum of 41 nT at 22/1935 UTC, solar wind speed increased to 737 km/s and the Bz component went negative to -39 nT at 22/1850 UTC. A prolonged period of mostly southward Bz occurred between 23/0013 UTC and 23/1246 UTC reaching as high as -25 nT. An SI of 48 nT (Hartland) was observed at 21/1650 UTC. The geomagnetic field responded with minor to major storm levels with severe storm periods observed between 22/1800-2100 UTC and 23/0000-0600 UTC. At 24/1258 UTC, the 22 June CME associated with the M6/2b flare on 22 June was observed in ACE data. Solar wind speeds increased from approximately 550 km/s to around 760 km/s with a relatively weak increase in total field from 5 nT to 13 nT. The Bz component was mostly positive during this event with negative values reaching a maximum of -11 nT between 25/0547 UTC and 25/1357 UTC. The geomagnetic field responded with only quiet to active periods on 24 June, but increased to minor to major storm levels mid-period on 25 June. Another CME associated with the M7/3b flare on 25 June arrived at 27/0223 UTC at the ACE spacecraft. Solar wind speeds increased from near 475 km/s to 860 km/s before slowly decreasing to 480 km/s by the end of the day. Total field reached a maximum of 13 nT at 27/0304 UTC and the Bz component was variable between +9 nT and -7 nT. As a result, the geomagnetic field never increased beyond unsettled conditions.
Forecast of Solar and Geomagnetic Activity 29 June – 25 July 2015
Solar activity is expected to be at low levels with a chance for M-class flare (R1-R2, Minor-Moderate) activity from 30 June through 24 July with the return of old Regions 2365 (S13, L=079) on 30 June, 2367 (S20, L=002) on 05 July, and 2371 (N13, L=302) on 11 July.
There is a chance for a greater than 10 MeV proton event from 11 July through 24 July with the return of old Region 2371 to the visible disk.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at high levels from 29-30 Jun and again from 08-19 July due to residual CME effects and recurrent coronal hole high speed streams (CH HSS).
Geomagnetic field activity is expected to be at active to minor storm (G1-Minor) levels from 06-08 July and again from 11-12 July due to recurrent CH HSS activity.
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