Are Saturn's Interchange Injections Organized by Rotational Longitude?

摘要

Saturn's magnetosphere has been extensively studied over the past 13 years with the now retired Cassini mission. Periodic modulations in a variety of magnetospheric phenomena have been observed at periods close to those associated with the emission intensity of Saturn kilometric radiation (SKR). Resulting from Rayleigh-Taylor like plasma instabilities, interchange is believed to be the main plasma transport process in Saturn's inner to middle magnetosphere. Here we examine the organization of equatorially observed interchange events identified based on high-energy (3-22 keV) H~+ intensifications by several longitude systems that have been derived from different types of measurements. The main question of interest here is as follows: Do interchange injections undergo periodicities similar to the Saturn kilometric radiation or other magnetospheric phenomena? We find that interchange shows enhanced occurrence rates in the northern longitude systems between 30° and 120°, particularly between 7 and 9 Saturn Radii. However, this modulation is small compared to the organization by local time. Additionally, this organization is weak and inconsistent with previous findings based on data with a limited time span.