• Weekly Highlights of Solar and Geomagnetic Activity, 24 - 30 July 2023

    From SWPC.Webmaster@noaa.gov@21:1/5 to All on Mon Jul 31 13:00:12 2023
    XPost: rec.radio.amateur.space, rec.radio.shortwave, rec.radio.info

    :Product: Weekly Highlights and Forecasts
    :Issued: 2023 Jul 31 0226 UTC
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    # Weekly Highlights and Forecasts
    Highlights of Solar and Geomagnetic Activity
    24 - 30 July 2023

    Solar activity was reached moderate levels. A total of 11 R1 (Minor)
    events were observed during the reporting period from four different
    active regions. The largest event was an M4.6 flare at 26/1037 UTC
    from Region 3376 (N23, L=228, class/area=Dso/180 on 18 Jul). The
    region also produced an M4.1 flare at 28/1158 UTC with an associated
    Type II radio sweep just as it rotated beyond the NW limb.

    Other activity included a Type II radio sweep on 24 Jul which was
    associated with activity on the farside. An additional Type II radio
    sweep was observed on 29 Jul from activity just beyond the NE limb.
    A filament eruption, centered near N27E25 and approximately 28
    degrees in length, began erupting after 28/2030 UTC. The event
    produced an Earth-directed CME signature in subsequent coronagraph
    imagery. The event was analyzed and modeled with the results
    suggesting arrival over 01-02 Aug.

    Two greater than 10 MeV proton enhancements were observed during the
    week. The first was observed beginning on 24 Jul. It was likely
    associated with energetic activity on the farside and did not reach
    the 10 pfu (S1 - Minor) threshold. The second event was associated
    with the M4.1 flare from the vicinity of Region 3376 just beyond the
    NW limb. The greater than 10 MeV proton flux levels began to
    increase shortly after the flare and reached the S1 event threshold
    at 29/0020 UTC. The event had a peak flux of 154 pfu (S2 - Moderate)
    at 29/0920 UTC. Flux levels decreased below the S1 threshold by
    30/1630 UTC.

    The greater than 2 MeV electron flux at geosynchronous orbit was
    mostly at normal to moderate levels through the period.

    Geomagnetic field activity ranged from quiet to G1 (minor) storm
    levels. G1 conditions were observed on 25-16 Jul in response to
    transient influence, likely from an event that occurred on 23 Jul. A
    weak shock was observed in the solar wind on around 25/2155 UTC.
    Total field increased to a peak of 17 nT and Bz reached as far south
    as -11 nT. Wind speeds increased to highs of ~555 km/s during the
    passage. Mostly quiet to unsettled conditions were observed during
    the other reporting days. A weak, positive polarity CH HSS onset was
    observed on 30 Jul and continued through the end of the period.

    Forecast of Solar and Geomagnetic Activity
    31 July - 26 August 2023

    Solar activity is likely to reach moderate levels
    (R1-R2/Minor-Moderate) on 31 Jul - 04 Aug. Activity for the
    remainder of the outlook period is likely to be at low levels, with
    a chance for M-class X-ray activity (R1).

    No proton events are expected at geosynchronous orbit.

    The greater than 2 MeV electron flux at geosynchronous orbit is
    likely to reach high levels on 02-04 Aug. The remainder of the
    outlook period is likely to be at moderate levels.

    Geomagnetic field activity is expected to range from quiet to G1
    (Minor) geomagnetic storm conditions. G1 levels are likely, with a
    chance for G2 (Moderate), on 01-02 Aug due to the anticipated
    influence of a CME that left the Sun on 28 Jul. Active conditions
    are likely on 26 Aug and unsettled conditions are likely 31 Jul,
    05-06 Aug, and 10-12 Aug due to multiple, recurrent CH HSSs.

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