Unexpected long-term variability in Jupiter's tropospheric temperatures

An essential component of planetary climatology is knowledge of the tropospheric temperature field and its variability. Previous studies of Jupiter hinted at non-seasonal periodic behaviour, as well as the presence of a dynamical relationship between tropospheric and stratospheric temperatures. However, these observations were made over time frames shorter than Jupiter's orbit or they used sparse sampling. Here we derive upper-tropospheric (330-mbar) temperatures over 40years, covering several orbits of Jupiter. Periodicities of 4, 7-9 and 10-14years were discovered that involve different latitude bands and seem disconnected from seasonal changes in solar heating. Anticorrelations of variability in opposite hemispheres were particularly striking at 16 degrees, 22 degrees and 30 degrees from the equator. Equatorial temperature variations are also anticorrelated with those observed 60-70km above. Such behaviour suggests a top-down control of equatorial tropospheric temperatures from stratospheric dynamics. Realistic future global climate models must address the origins of these variations in preparation for their extension to a wider array of gas giant exoplanets. Infrared observations of Jupiter obtained in a 40-yr timespan between 1978 and 2019 show long-term variations of Jupiter's tropospheric temperature with different periodicities, particularly at tropical latitudes, which often bear some connection with stratospheric temperature fluctuations.