PSP/RFS Observations of a Circularly-Polarized Type III Radio Storm

In late June 2022, the Radio Frequency Spectrometer instrument on the Parker Solar Probe observed an interplanetary (IP) Type III radio storm lasting several days. The storm exhibited a strong signature of right-handed circular polarization in the ~1-10 MHz frequency range. The overall intensity and degree of circular polarization varied over the duration of the storm, with both reaching a maximum on June 23. We compare the storm observations with recent measurements of circularly polarized emission in isolated (non-storm) IP Type III bursts and an IP Type II burst, and discuss possible implications for the generation and propagation of the radio emission.