The impact of Coriolis approximations on the environmental sensitivity of idealized extratropical cyclones

The precise influence of climate change on extratropical cyclone genesis and evolution is an important (but as yet unsolved) problem, given their physical and economic impact on a large portion of the planet’s population. However, extratropical cyclones are also affected by the competing influences of forcing mechanisms at a wide range of spatial scales, complicating the problem. While the advent of idealized numerical modeling has allowed great strides in addressing these complications and achieving some qualitative consensus in the literature, there is still some quantitative disagreement about response magnitude and where local maxima and minima in the response may be located. Thus, the advantages inherent in the variety of idealized numerical modeling methods used to address this problem are also a drawback, as it can be difficult to draw one-to-one comparisons across experiments. Although the effects of particular model architecture choices such as microphysical and cumulus schemes are well-documented, others are less understood. In this study, we examine the role of Coriolis approximations by comparing a new set of ETC sensitivity experiments using a linear β -plane approximation to an existing set of extratropical sensitivity experiments using a constant f -plane approximation. ETCs within the new β -plane experiment are found to generally decrease in strength with temperature, as measured by both minimum sea level pressure and maximum eddy kinetic energy (EKE). A small increase in EKE is observed at the warmest temperatures, likely due to diabatic influences disrupting flow within the warm conveyor belt. While seemingly contradictory to the previous f -plane results, the two experiments are instead found to be qualitatively similar upon further inspection, with an offset of approximately 8 K. This offset is primarily due to the Coriolis approximations, although the initial stability profile (affected by the Coriolis approximation) has a marginal influence.