Viewing archive of Saturday, 21 September 2019

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2019 Sep 21 1230 UTC

SIDC Forecast

Solar flares

Quiet conditions (<50% probability of C-class flares)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Sep 2019	067	005
22 Sep 2019	067	007
23 Sep 2019	067	013

Bulletin

Solar X ray flux remained below B level throughout the period. The Solar disk is spotless and X-ray flux is expected to remain at or below background levels.

The filament eruption from the Southern hemisphere that was mentioned in yesterdays bulletin has been investigated further. While the STEREO/COR2 coronagraph data indicate a corresponding narrow CME that may be Earth directed its corresponding projected speed is below 300 km/s. SoHO/LASCO data do not show any clear signs of any (partial) halo CME but only some weak signatures of Eastward propagating material. It is hence assessed that the ejecta are possibly off the Sun-Earth line towards the East. Even if the ejecta would be towards the Earth, with such a slow speed it is unlikely to have any significant impact. Hence no specific arrival forecast is made. There were otherwise no Earth-directed CMEs observed in coronagraph data.

Proton levels were at background values and are expected to remain so.

Solar wind conditions were near nominal. Around 5:00UT Solar wind speed increased fairly suddenly from around 300 km/s to around 360 km/s along with total magnetic field going up from around 3nT to around 7nT. At that time the magnetic field phi angle started fluctuating between the positive and negative sector and Bz became pronounced negative. Solar wind conditions are expected to remain near nominal over the next 48 hours then followed towards the end of day 3 with the onset of a high speed stream related to the negative polarity equatorial coronal hole that passed the central meridian yesterday.

Geomagnetic conditions were quiet to unsettled (NOAA Kp 1-3 and local K Dourbes 0-3). Quiet to unsettled geomagnetic conditions are expected to continue the next 48 hours with later, towards the end of day 3, unsettled to active conditions expected under the high speed stream influence.

Today's estimated international sunspot number (ISN): 000, based on 23 stations.

Solar indices for 20 Sep 2019

Wolf number Catania	///
10cm solar flux	067
AK Chambon La Forêt	008
AK Wingst	003
Estimated Ap	002
Estimated international sunspot number	000 - Based on 30 stations

Noticeable events summary

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

All times in UTC

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