Speaker
Description
The forecast of space weather impacts related to CMEs which interact with high-speed stream is very challenging. ICMEs are known to be among the most important origins of geomagnetic storms because they usually carry out-of-the-ecliptic strong magnetic fields and are often associated with interplanetary shocks. The internal ICME structure is characterized as a magnetic flux rope, which may carry anti-parallel magnetic field compared to the day-side Earth’s magnetic field. In the cases when these ICMEs interact with high-speed streams it may happen that their internal magnetic fields are intensified close to the interface of the two structures. This was observed to happen on early February 2022, when a major loss of commercial satellites took place during their launch to low Earth orbit. Even though the space weather forecast for that period was of minor impacts, a moderate geomagnetic disturbance took place due to a pressure balanced structure. An unexpected high intensity southward magnetic field was observed during the ICME passage at the Earth. Disturbance Storm Time (Dst) index reached a negative peak of -66 nT during this period. Even though this is a relatively rare scenario, other similar events were observed in other periods of time, and the commercial impact of the 2022 event highlights the importance of addressing them. In this work we address the challenges that CMEs interacting with high-speed streams pose to space weather forecasting.
