Viewing archive of Monday, 21 September 2015

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2015 Sep 21 1230 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Sep 2015	117	010
22 Sep 2015	123	007
23 Sep 2015	129	009

Bulletin

Four active regions were reported by NOAA today, with two of them (NOAA ARs 2415 and 2420) having beta-gamma configurations of their photospheric magnetic field. After the M2.1 flare in the NOAA AR 2415 yesterday, the flaring activity became dominated by the NOAA AR 2420. It produced four C-class flares today, the strongest one being the C8.8 flare peaking at 05:18 UT. No Earth-directed CMEs were associated with these flares. We expect flaring activity on the M-level, mostly in the NOAA AR 2420. The solar proton flux at energies above 10 MeV decreased again after the peak yesterday evening, and is currently only slightly above the background. Although a further increase is not excluded due to the approach of the interplanetary shock driven by the CME associated with yesterday's M2.1 flare, we expect the proton flux to remain below the event threshold. A small equatorial coronal hole reached the solar central meridian today. The fast solar wind flow from this coronal hole is expected to arrive at the Earth on September 24. After the arrival of the interplanetary shock yesterday, the solar wind speed at the Earth is fluctuating between 500 and 600 km/s. The interplanetary magnetic field magnitude decreased down to 6-7 nT. The geomagnetic conditions are quiet to unsettled and are expected to remain so, with isolated intervals of active conditions possible but unlikely.

Today's estimated international sunspot number (ISN): 071, based on 18 stations.

Solar indices for 20 Sep 2015

Wolf number Catania	///
10cm solar flux	110
AK Chambon La Forêt	043
AK Wingst	030
Estimated Ap	035
Estimated international sunspot number	062 - Based on 27 stations

Noticeable events summary

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

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