Viewing archive of Wednesday, 25 December 2013

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2013 Dec 25 1246 UTC

SIDC Forecast

Solar flares

Eruptive (C-class flares expected, probability >=50%)

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
25 Dec 2013	123	023
26 Dec 2013	125	015
27 Dec 2013	128	007

Bulletin

There were eight C flares on the Sun during the past 24 hours, released by NOAA AR 11928 and 11936. The brightest one was a C4.7 flare from NOAA AR 11928 peaking at 06:39 UT on December 25. In the next 48 hours, the probability for C flares is high (around 70%) and for M flares around 25%, mainly from NOAA AR 11928 and 11936. Solar wind speed as observed by ACE suddenly increased from about 290 to 320 km/s around 20:40 UT on December 24, accompanied by a rise in solar wind density. Since then, the magnitude of the Interplanetary Magnetic Field has gradually increased from about 3 to about 12 nT and its phi angle behaved chaotically until 4:00 UT on December 25, when it started increasing linearly over time. These measurements are consistent with the arrival of the flux robe of an unidentified CME around 4h UT on December 25, preceded by a shock which started around 20:40 UT on December 24. Though Bz is having extended periods of -10 nT, geomagnetic activity has remained quiet over the past 24 hours (NOAA Kp between 0 and 3). Due to the expected arrival of a coronal hole high speed stream, quiet to active geomagnetic conditions are expected in the second half of December 25 and on December 26, with a chance of minor storm excursions. Quiet to active conditions are likely on December 27.

Today's estimated international sunspot number (ISN): 070, based on 11 stations.

Solar indices for 24 Dec 2013

Wolf number Catania	///
10cm solar flux	128
AK Chambon La Forêt	007
AK Wingst	002
Estimated Ap	002
Estimated international sunspot number	078 - Based on 11 stations

Noticeable events summary

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

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