Vertically-resolved observations of Jupiter’s quasi-quadrennial oscillation from 2012 to 2019

Over the last eight years, a rich dataset of mid-infrared CH4 observations from the TEXES instrument at IRTF has been used to characterize the thermal evolution of Jupiter’s stratosphere. These data were used to produce vertically-resolved temperature maps between latitudes of 50◦S and 50◦N, allowing us to track approximately two periods of Jupiter’s quasi-quadrennial oscillation (QQO). During the first five years of observations, the QQO has a smooth sinusoidal pattern with a period of 4.0 ± 0.2 years and an amplitude of 7 ± 1 K at 13.5 mbar (our region of maximum sensitivity). In 2017, we note an abrupt change to this pattern, with the phase being shifted backwards by ∼1 year. Searching for possible causes of this QQO delay, we investigated the TEXES zonally-resolved temperature retrievals and found that in May/June 2017, there was an unusually warm thermal anomaly located at a latitude of 28◦N and a pressure of 1.2 mbar, moving westward with a velocity of 19 ± 4 ms−1. We suggest that there may be a link between these two events.