Viewing archive of Sunday, 23 August 2015

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2015 Aug 23 1230 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
23 Aug 2015	119	026
24 Aug 2015	120	012
25 Aug 2015	121	019

Bulletin

Solar activity remained enhanced over the past 24 hours, with active region (AR) 2403 (Macintosh:Ekc/Type:Beta-Gamma-Delta) showing continued flux emergence, and producing several C-class flares and two M-class flares; an M2.2 class flare on 2015-Aug-22 peaking at 13:23 UT, and an M3.5 class flare at 21:24 UT. An earlier M1.2 class flare produced by AR 2403, peaking at 06:49 UT on 2015-Aug-22, was associated with a very faint halo coronal mass ejection (CME) first observed in LASCO imagery at 07:12 UT. Although it is difficult to estimate the speed with which the CME is travelling toward the Earth in the absence of STEREO data, it is estimated that the CME has a speed of roughly 675 km/s, and is expected to arrive at the Earth on 2015-Aug-25 at 03:14 UT with an error +/- 12 hours. In the past 24 hours ARs 2401 and 2402 have passed over the west limb, AR 2404 (Macintosh:Cro/Type:Beta) has shown some evidence of growth, but still remains small. Solar activity is expected to remain active over the next 24 hours, with AR 2403 producing C-class flares with the possibility of M and X-class flares. The solar wind speed, as recorded by the ACE satellite, remained roughly constant yesterday, around 400 km/s, and then abruptly jumped to around 520 km/s between 06:00 UT and 09:00 UT this morning, this was combined with a predominantly negative Bz interplanetary magnetic field (IMF) of -10 nT, creating geomagnetic storm conditions. NOAA reported Kp=6 and the local Dourbes station reported K=5. The increase in speed is believed to be caused by a co-rotating interaction region (CIR)/coronal hole (CH) high speed stream (HSS). The total interplanetary magnetic field (IMF) strength has shown some variation but remained around 12 nT, and the Bz component was mainly fluctuating around 0 nT yesterday but dropped to -10 nT at 05:00 UT this morning, creating the above mentioned storm conditions. Prior to the storm this morning, geomagnetic conditions varied between quiet and active over the past 24 hours, with the local (Dourbes) K-index reaching 4 and the NOAA K-index reaching 3. There is currently a small coronal hole located at S15W40 which is possibly the cause of the enhanced solar wind speeds. Geomagnetic activity is expected to be enhanced over the next 24 to 48 hours due to a combination of the above mentioned CH HSS and the possible arrival of the two CMEs produced earlier in the week, expected to arrive around 03:14 UT on 2015-Aug-25 and 07:10 UT on 2015-Aug-26.

Today's estimated international sunspot number (ISN): 069, based on 15 stations.

Solar indices for 22 Aug 2015

Wolf number Catania	///
10cm solar flux	117
AK Chambon La Forêt	021
AK Wingst	014
Estimated Ap	011
Estimated international sunspot number	070 - Based on 28 stations

Noticeable events summary

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

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