Viewing archive of Thursday, 11 September 2014

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2014 Sep 11 1236 UTC

SIDC Forecast

Solar flares

Active (M-class flares expected, probability >=50%)

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Proton event in progress (>10 MeV)

	10cm flux	Ap
11 Sep 2014	164	018
12 Sep 2014	168	026
13 Sep 2014	170	059

Bulletin

On 10 September, NOAA 2158 produced an X1.6 flare peaking at 17:45UT. It was accompanied by an EIT wave, coronal dimming, and post-flare coronal loops. Around 21:00UT, the proton flux gradually started to increase, and a minor proton event started around 03:00UT. Associated to this strong flare was a full halo CME, first observed by SOHO/LASCO at 18:00UT. It had a plane-of-the-sky speed of at least 800 km/s and is directed to Earth. Estimated arrival time is 21 September at 21:00UT (+/- 12 hours). There are currently 9 sunspot groups visible. NOAA 2158 has no delta structure, but the main spot remains close to opposite polarity flux to the south and east. NOAA 2157 retained its delta structure in its main trailing spot. An active region that is about to round the northeast limb was responsible for a C4 flare peaking at 03:49UT. This was the strongest of 3 low-level C-class flares that were observed during the last 24 hours. M-class flares are expected, with a chance on another X-class event. Solar wind speed was mostly between 350 and 400 km/s, with Bz varying between +6 and -7 nT. A sector boundary crossing was observed around 21:30UT, with IMF turning away from the Sun. Brief periods of active geomagnetic conditions were observed over the last 12 hours, otherwise the geomagnetic field was unsettled. Unsettled to active geomagnetic conditions are expected for 11 and most of 12 September in response to the possible impact of the halo CME related to the M4.5 flare from 9 September. This will then be followed by the arrival of the halo CME related to the X1.6 flare late on 12 or early on 13 September. Pending the orientation of the CME's magnetic field, this may result in a major geomagnetic storm, with locally severe geomagnetic storming possible.

Today's estimated international sunspot number (ISN): 114, based on 13 stations.

Solar indices for 10 Sep 2014

Wolf number Catania	184
10cm solar flux	160
AK Chambon La Forêt	018
AK Wingst	010
Estimated Ap	011
Estimated international sunspot number	113 - Based on 21 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

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