Last Weeks
The solar activity was at high levels since our latest post on March 24 due to a very active region 12975. AR12975 caused 11 M-Class and 1 X-Class flare within a week! Some of the flares caused even Solar Energetic Particle and Radiation Belt enhancement events! AR12975 was also the source region for more than 4 CMEs. It was a highly active week!
X-Class CMEs are rare during this phase of the solar cycle. Thus, the X1.3 flare raised some attention. The flare peaked on 30 March at 17:37 UTC. This flare caused SEP in one hour due to high energetic proton flux.
Moreover, an Earth-directed CME with 808 km/s speed is observed with the X1.3 flare. This CME arrived on Earth on March 2 and caused an Interplanetary shock. Kp level reached 5 and Dst indice reached -42 nT at its minimum.
Another significant CME was a C-type with a speed of 702 km/s on April 3. The CME arrived on Earth on April 6 and caused IPS. Yet, the impact of the IPS was mild and Kp level remained at 4 which means there was no geomagnetic storm.
After the passage of AR12975 the solar activity returned to nominal levels.
Solar activity was at low levels within the last 24 hours. There were 61 sunspots with 7 active regions on the visible disk. There were no significant solar flares. The only coronal hole is located at the center of the visible disk. The solar wind speed has decreased steadily until earlier hours, after a sudden jump, it started to decrease again. The strength of the southward IMF was 5.78 nT at its maximum. The minimum magnetopause standoff distance was 10 Re. The maximum Kp level was 4 due to the HSS and the influences of April 3 CME. The geomagnetic indices Dst varied between -24 and 11 nT, and AE was below 1000 nT which indicate somewhat quiet conditions. The F10.7 radio flux was 117 sfu which is normal during the ascending phase of the solar cycle.
The solar activity is expected to remain at low levels in the following days. A glancing blow from the filament eruption on April 7, 05:18 UTC is expected. This arrival might cause a disturbance in the geomagnetic conditions, yet no geomagnetic storm is expected. The unsettled conditions are expected to remain at this trend due to the central CH and the late effects of the April 3 CME. ASSA flare model predicts the occurrence possibility of C, M, and X class flares as, 44%, 10%, and 0% respectively.
Forecaster: Ezgi Gülay
MSc. Student
Faculty of Aeronautics and Astronautics, ITU