Past Events
Between the period with our last forecast at June 29 and yesterday July 5, the solar activity was at very low levels. Two sunspot groups attempted to become active regions at SE limb but they eventually decayed before numbered as active regions. No CMEs or flares were observed. Solar wind speed started to increase on July 4, from 300 km/s and reached to 400 km/s on the same day around 18 UTC. This CH HSS still continue and increased up to 500 km/s.
On July 5, a new active region emerged at NE limb near the center of the visible disk and it has numbered as AR2766. It is believed that this AR belongs to the previous solar cycle 24 due to its polarity. On the same day, a CME was observed by LASCO C1 at 14.24 UTC, yet it is not Earth-directed. This CME is associated with the prominence eruption at the SE limb which observed at around 6.30 UTC.
The geomagnetic indice Dst has negative values mostly varying between -20 and -40 nT. AE indice started to increase on July 4 with the increase of the solar wind speed.
Within the last 24 hour solar activity was at low levels. The CME observed on July 5 and the associated prominence eruption did not cause any near Earth affect. The AR2766 is located at the central meridian and around 5°N latitude and caused no flares. The coronal hole which caused the current HSS is turned farside. The remaining coronal holes are the on the poles, and one small area at the SW limb close to the center, and the other one is at NE limb. The solar wind speed varied between 426 and 515 km/s in the last 24 hours. The strength of southward IMF was 6.37 nT. The minimum magnetopause standoff distance was 8.5 Re. The maximum Kp was 3. Geomagnetic indice Dst showed quiet to unsettled conditions by varying between -45 and -30 nT. AE indice was mostly greater than 500 nT, yet below the 1000 nT threshold due to the HSS. The F10.7 radio flux was 69 sfu which is normal during solar minimum.
Solar activity is expected to remain at low levels in the following days. The observed CME was not Earth-directed. The AR2766 is a weak sunspot group. Thus no significant flares are expected. ASSA flare model predicts the occurrence possibility of C, M and X class flares as, 9%, 1% and 0% respectively. The increase in the solar wind speed and associated unsettled geomagnetic conditions are expected to continue at their current levels for the rest of the day. The conditions are expected to turn to nominal conditions in the following days.
Forecaster: Ezgi Gülay
MSc. Student
Faculty of Aeronautics and Astronautics, ITU
Supervisor: Dr. Emine Ceren Kalafatoğlu Eyigüler