Subject: Weekly Highlights of Solar and Geomagnetic Activity, 11 - 17 September 2023

:Product: Weekly Highlights and Forecasts
:Issued: 2023 Sep 18 0138 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC contact on the Web
# https://www.swpc.noaa.gov/content/subscription-services
#
# Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity
11 - 17 September 2023

Solar activity ranged from low to moderate (R1 - Minor) levels. Low
levels were observed on 13 and 17 Sep while moderate levels were
observed on 11-12 and 14-16 Sep. Regions 3423 (N16, L=281,
class/area Ekc/420 on 11 Sep), 3425 (N23, L=246, class/area Dai/140
on 08 Sep) and 3429 (N11, L=207, class/area Dai/090 on 15 Sep) were
responsible for the moderate levels activity. The largest event of
the period was an M3.3/1b flare from Region 3429.

A filament eruption in the vicinity of Region 3423 (N15W72,
Eko/beta) produced an M1 flare that began at 14/0640 UTC. The x-ray
flare reached a peak of M1.4 at 14/0745 UTC due to a contributing
flare from Region 3429 (N10E05, Eai/beta) which obscured the natural
x-ray peak of the filament eruption. The filament eruption produced
a CME signature, first visible in SOHO/LASCO C2 imagery at 14/0712
UTC. Analysis and model output suggested an Earth arrival early on
17 Sep.

No proton events were observed at geosynchronous orbit.

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

Geomagnetic field activity ranged from quiet to G2 (Moderate)
levels. Quiet levels were observed on 11 Sep through midday on 12
Sep. Unsettled to G2 (Moderate) levels were observed from midday on
12 Sep through 13 Sep due to CME and positive polarity CH HSS
effects. Unsettled to active levels were observed on 14-15 Sep due
to positive polarity CH HSS on 14 Sep and negative polarity CH HSS
effects on 15 Sep. Mostly quiet levels were observed on 16 Sep.
Unsettled to active levels were observed on 17 Sep due to transient
effects from the 14 Sep CME.

Total field readings, through the period, generally averaged 4-7 nT
with a peak to 21 nT midday to late on 12 Sep. The Bz component
reached a maximum southward reading of -20 nT late on 12 Sep. Wind
speeds ranged from lows near 340 km/s on 11-12 Sep to a high reading
of 525 km/s midday to late on 14 Sep.

Forecast of Solar and Geomagnetic Activity
18 September - 14 October 2023

Solar activity is expected to be at low to moderate (R1-R2 / Minor
to Moderate) levels throughout the period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is
expected to be at low to moderate levels through the period.

Geomagnetic field activity is likely to be at G1-G2 (Minor to
Moderate) levels on 19 Sep and unsettled to active levels on 20 Sep,
all due to CME effects. Unsettled to active levels are likely on 21,
23-24 and 28-30 Sep due to CH HSS activity. Mostly quiet levels are
expected on 18, 25-27 Sep and 01-14 Oct.


--- MBSE BBS v1.0.8.4 (Linux-x86_64)
* Origin: NOAA Space Weather Prediction Center (3:633/280.2@fidonet)