Saturn's Polar Atmosphere

TL;DR

This chapter reviews current knowledge of Saturn's polar atmosphere, emphasizing Cassini mission findings, features like the hexagon and vortex, and seasonal evolution, highlighting advances and remaining questions in planetary atmospheric science.

Contribution

It provides an updated synthesis of observational and theoretical insights into Saturn's polar atmosphere, especially from Cassini data, focusing on the north polar region and its unique features.

Findings

Detailed analysis of Saturn's north polar hexagon and vortex.

Seasonal changes observed in polar regions from 2004 to 2017.

Comparison of northern and southern polar atmospheric features.

Abstract

This book chapter, Saturn's Polar Atmosphere, is to be published by Cambridge University Press as part of a multi-volume work edited by Kevin Baines, Michael Flasar, Norbert Krupp, and Thomas Stallard, entitled "Saturn in the 21st Century." This chapter reviews the state of our knowledge about Saturn's polar atmosphere that has been revealed through Earth- and space-based observation as well as theoretical and numerical modeling. In particular, the Cassini mission to Saturn, which has been in orbit around the ringed planet since 2004, has revolutionized our understanding of the planet. The current review updates a previous review by Del Genio et al (2009; Saturn Atmospheric Structure and Dynamics, Chapter 7 of "Saturn from Cassini-Huygens"), written after Cassini's primary mission phase that ended in 2008, by focusing on the north polar region of Saturn and comparing it to the southern high latitudes. Two prominent features in the northern high latitudes are the northern hexagon and the north polar vortex; we extensively review observational and theoretical investigations to date of both features. We also review the seasonal evolution of the polar regions using the observational data accumulated during the Cassini mission since 2004 (shortly after the northern winter solstice in 2002), through the equinox in 2009, and approaching the next solstice in 2017. We conclude the current review by listing unanswered questions and describing the observations of the polar regions planned for the Grand Finale phase of the Cassini mission between 2016 and 2017.