Solar wind parameters indicate the arrival of a slow-moving CME

Solar wind parameters indicate the arrival of a slow-moving CME

Solar wind parameters over the past 12 hours indicated the arrival of a slow-moving Coronal Mass Ejection (CME), likely produced on April 10. A period of G1 - Minor storming began at 08:59 UTC on April 15. Another enhancement in parameters is expected on April 16 due to the arrival of CIR ahead of negative polarity CH HSS.

At approximately 03:29 UTC on April 15, the total field increased to 8 nT while the Bz component deflected south to near -7 nT for approximately 2 hours.

Total field continued to increase to 10 nT by 09:20 UTC with solar wind speed ranging from 358 - 461 km/s.

Enhancements in the total field are likely to continue through April 15 as transient effects continue, SWPC forecasters noted.

However, another enhancement in solar wind parameters is expected on April 16 due to the arrival of a co-rotating interaction region (CIR) preceding an isolated negative polarity coronal hole high speed stream (CH HSS).

Elevated solar wind speed is anticipated to continue into April 17 and will likely be around 500 - 550 km/s based on sparse STEREO A Mag/Plastic data.

In 24 hours to 12:30 UTC on April 15, the geomagnetic field was at quiet to G1 - Minor geomagnetic storm levels due to CME effects. Kp-Index of 5 (G1 - Minor) threshold was reached at 08:59 UTC.

Quiet to active levels are expected for the rest of the UTC day on April 15 as CME effects persist.

Quiet to active levels are expected on April 16 and 17 with G1 - Minor storm conditions likely on April 17 as a negative polarity CH HSS becomes geoeffective.

Solar activity was at very low levels in 24 hours to 12:30 UTC today. 

Region 2814 (S22W24, Cri/beta) continued its growth during the period and then started its decay trend. Low-level B-class flares were observed from a Region near S25E90, however, no spots are visible in white light imagery as of yet.

No Earth-directed CMEs were observed.

Solar activity is expected to be very low with a slight chance for C-class flares through April 17.

The greater than 2 MeV electron flux was normal to moderate and the greater than 10 MeV proton flux remained at background values.

The greater than 2 MeV electron flux is expected to be normal to moderate on April 15 and 16 but CH HSS influences will provide for a chance of high levels on April 17. The greater than 10 MeV proton flux is expected to continue at background levels.

Featured image: NASA/SDO AIA 304, NASA/ESA LASCO

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