Authors: Wenwen Wei(Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA), Christina O. Lee(Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA)

The energy spectra of energetic particles provide essential information to help resolve the underlying fundamental physics of their injection, acceleration, and transport processes. In this work, we investigate the radial and longitudinal evolution of a sunward streaming energetic ion event based on Solar Orbiter, STEREO A, and Wind/ACE observations. This event appears at the rising phase of a widespread solar energetic particle (SEP) event that was associated with the farside coronal mass ejection on February 15, 2022, and it is characterized by very large and long-lasting anisotropies. Our analysis indicates that the energy spectra of this event observed by Solar Orbiter can be fitted into three parts: a power-law spectrum at both low and high energies, and an Ellison-Ramaty spectrum at intermediate energies. However, the energy spectra at STEREO A and Wind/ACE are two parts that no power-law spectrum at low energies was observed probably due to data gaps. Moreover, we find that the transport effect may not be able to explain the energy spectral variations at intermediate energies, and we suppose the injection profiles may change with time. Our results show that the energy spectra of energetic ions can be used to disentangle their injection profiles as well as transport processes, highlighting the importance of understanding the radial and longitudinal evolution of energy spectra.