The GIANTCLIMES programme spanned seven years (2017-2024), bridging the gap between the end of Cassini’s exploration of Saturn, and the world-leading new observations of all four giant planet systems from JWST. GIANTCLIMES allowed us to fully exploit the wealth of ground-based records of natural climate variability on all four giant planets before JWST, producing long-term records of temperature, clouds, and composition on all four worlds. Notable results for the three work packages are as follows:
• WP1: Jupiter's Climate: WP1 explored the atmospheric variability of Jupiter over long spans of time, combining data from Earth-based observatories with new observations from NASA’s Juno spacecraft. Using more than three decades of ground-based observations, we identified periodic cycles of atmospheric variability, both in the deep clouds, in the stratosphere, and in tropospheric temperatures. Patterns at widely-separated latitudes appear to be interconnected (suggesting deep origins), and prone to teleconnections by extreme storm events and belt/zone variability. These studies were used as context for Juno’s close-in studies in microwave and infrared light, and for JWST spectroscopic observations of regions of interest in 2022-23. Ultimately, the developing understanding of jovian climate cycles, meteorology, and chemistry have supported our role in the science planning for ESA’s Jupiter Icy Moons Explorer, which launched in 2023.
• WP2: Saturn's Seasonal Stratosphere: Cassini completed its unprecedented exploration of Saturn in 2017, allowing the GIANTCLIMES team to publish new insights into the long-term seasonal variations in Saturn's atmosphere. We supplemented this work using our long-term ground-based infrared campaign, which extends both before and after Cassini's mission, allowing us to track a full seasonal cycle of the giant planet for the first time, and revealing hints of inter-annual variability in Saturn’s seasonal response. These projects culminated with the publication of the first JWST maps of Saturn's northern summer hemisphere in 2022, showing how large-scale circulation patterns completely switch direction over the course of a Saturnian year.
• WP3: Ice Giants: Uranus and Neptune remain the least explored planets in our solar system. GIANTCLIMES enabled the first maps of Uranus' stratosphere and a comprehensive assessment of Neptune's stratosphere over two decades, revealing surprising sub-seasonal variability for the first time. These long-term studies paved the way for the first global maps of the Ice Giant atmospheres from JWST in 2022-23, the most significant new dataset since Voyager.
