Speaker
Description
We investigate a Phantom Forbush Decrease event on January 31, 2012. Phantom Forbush Decreases are sudden cosmic ray depressions without clear in-situ signatures of interplanetary coronal mass ejections (ICMEs), and their origin remains poorly understood. Using multi- instrument remote-sensing, in-situ, and ground-based data, six preceding CMEs are identified,including two fast full-halo events. Trajectory and modeling analyses suggest a shock–shock interaction produced a large-scale merged structure that propagated toward Earth, explaining the observed cosmic ray decrease despite the absence of a detectable ICME. These findings provide new insight into the origin of Phantom Forbush Decreases and the role of complex heliospheric disturbances.