We are all familiar with seasonal effects on Earth. They are observed not only in our living environment but also in the stratosphere, the ionosphere and beyond. Seasonal effects have also been observed on other bodies of the solar system and in their environment, by remote sensing instruments or in situ probes/rovers. Seasonal variability is currently well studied on Mars and processes such as the formation of CO2 frost on the south polar cap or the condensation of H2O on both polar caps are now well understood. Thanks to long term observations by Cassini-Huygens, the Saturn system is proving to be a rich laboratory for studying seasonal variations in a variety of environments. Several seasonal variability effects are observed in the highly complex Titan system, on its surface, in the surface/atmosphere interaction, and in all its atmosphere/ionosphere layers. For example, the apparition of equatorial storms at the equinox, and the formation of mid-latitude clouds in the southern hemisphere during winter are meteorological phenomena on Titan that are revealed by Cassini-Huygens and by complementary long term ground-based monitoring observations. Seasonal O2-CO2 exospheres and possible seasonal frosts at Rhea and Dione are shown by Cassini measurements. Cassini also shows seasonal variations in the interaction between the atmosphere/ionosphere of Saturn's rings which in turn are causing seasonal variations in the water flux in Saturn upper atmosphere and in the magnetospheric O2+ density. Observations by Earth-based and ground-based telescopes allow studying remotely seasonal variations in Uranus and Neptune atmospheres and on Pluto and its main satellite Charon.

Observations, their interpretation, and modelling work related to sessional variability across all planets of the solar system are topics relevant to this session. An important goal of the session is to highlight the common physical phenomena that govern seasonal variability in the solar system. We will discuss how the study of the same processes on Earth and other solar system bodies helps to understand which physical and chemical parameters control the processes.

This session will include solicited keynote reviews and oral and poster contributions. You are invited to submit abstract for either a contributed oral talk or a poster presentation that cover any relevant topic to the session.