@article{763c7d467f7e40fda6e0b517b7858938,
title = "Seasonal variation of north–south asymmetry in the intensity of Saturn Kilometric Radiation from 2004 to 2017",
abstract = "This study investigates the long-term variation of Saturn Kilometric Radiation (SKR) intensity observed by the Radio and Plasma Wave Science (RPWS) instrument on board the Cassini spacecraft from 2004 (southern summer) to 2017 (northern summer). The results show that the SKR intensity was brighter in the summer hemisphere than in the winter hemisphere, which was clearly seen in the south-to-north SKR intensity ratio. Over the long-term, the southern SKR intensity became 100 times smaller during northern summer, while the northern SKR intensity remained fairly constant. It means that the reversal in the intensity ratio was mainly caused by the long-term reduction of southern SKR intensity as Saturn's southern hemisphere moved from summer to winter, not the enhancement of northern SKR from winter to summer. We also investigated the possible contributions from the long-term solar EUV flux and solar wind dynamic pressure during the solar cycles 23 and 24, but we found that their impact on the SKR long-term variations was less than Saturn's seasonal changes associated with the variation of the tilt of its rotational axis with respect to the Sun. We further compared the long-term variation of the SKR intensity and the SKR period over half a Kronian year. The former showed more systematic variations which do not compare to those seen in the SKR periods.",
keywords = "Aurora, Saturn, Saturn Kilometric Radiation (SKR), Seasonal variation",
author = "Yuki Nakamura and Yasumasa Kasaba and Tomoki Kimura and Laurent Lamy and Baptiste Cecconi and Georg Fischer and Ayumu Sasaki and Chihiro Tao and Fuminori Tsuchiya and Hiroaki Misawa and Atsushi Kumamoto and Akira Morioka",
note = "Funding Information: We are grateful to the Cassini RPWS team for providing the valuable datasets. The authors also acknowledge the team of the CELIAS/SEM experiment on the SOHO spacecraft. French coauthors were supported by CNRS ( Centre National de la Recherche Scientifique ), Observatoire de Paris, and CNES (Centre National d{\textquoteright}Etudes Spatiales). YN was supported by The International Joint Graduate Program in Earth and Environmental Sciences, Tohoku University (GP-EES) . YK also thanks to the support from JAXA JUICE project for the outer planet radio emission studies linked to our contributions in Radio and Plasma Wave Investigation (RPWI) for ESA JUICE mission. TK was supported by a Grant-in-Aid for Scientific Research ( 16K17812 ) from the Japan Society for the Promotion of Science ( JSPS ). This work was also supported JSPS and MAEDI under the Japan-France Integral Action Program (SAKURA) . Funding Information: We are grateful to the Cassini RPWS team for providing the valuable datasets. The authors also acknowledge the team of the CELIAS/SEM experiment on the SOHO spacecraft. French coauthors were supported by CNRS (Centre National de la Recherche Scientifique), Observatoire de Paris, and CNES (Centre National d'Etudes Spatiales). YN was supported by The International Joint Graduate Program in Earth and Environmental Sciences, Tohoku University (GP-EES). YK also thanks to the support from JAXA JUICE project for the outer planet radio emission studies linked to our contributions in Radio and Plasma Wave Investigation (RPWI) for ESA JUICE mission. TK was supported by a Grant-in-Aid for Scientific Research (16K17812) from the Japan Society for the Promotion of Science (JSPS). This work was also supported JSPS and MAEDI under the Japan-France Integral Action Program (SAKURA). Publisher Copyright: {\textcopyright} 2019 Elsevier Ltd",
year = "2019",
month = nov,
day = "15",
doi = "10.1016/j.pss.2019.104711",
language = "English",
volume = "178",
journal = "Planetary and Space Science",
issn = "0032-0633",
publisher = "Elsevier Limited",
}