Beware of Inertial Instability Masquerading as Gravity Waves in Stratospheric Temperature Perturbations

Rapp, Dornbrack, and Preusse (2018, https://doi.org/10.1029/2018GL079142) uses radio occultation observations and meteorological data from the European Centre for Medium Range Weather Forecasting to quantify the effect of inertial instability on stratospheric temperature variability. A very interesting by-product of their study is the take-away message that inertial instability "pancake structures" may be misidentified as being caused by gravity waves. We place this result in the context of inertial instability research. We concur with Rapp et al.'s caution to researchers to first examine the large-scale meteorological environment to rule out inertial instability when analyzing temperature fluctuations that appear to be gravity wave signals in vertical profile data.