Error-Growth Dynamics in Idealized Midlatitude Cyclones with Different Moist Baroclinic Life Cycles

The development of midlatitude cyclones, which largely dominate cool-season midlatitude weather, is driven by baroclinic instability on synoptic scales. We previously used convection-permitting idealized simulations of midlatitude cyclones developing in f-plane channels to show that synoptic-scale, adjoint-derived perturbations more strongly affect this unstable growth than equal-magnitude, small-scale perturbations that grow upscale from moist convection. Nevertheless, other recent studies have used global models to suggest that error growth in midlatitude weather systems is, on average, dominated by nonlinear near-tropopause dynamics rather than by differences in the tropospheric-deep baroclinic instability. Here, we place our results in the context of these recent studies by examining the physical processes responsible for error growth in our idealized midlatitude-cyclone simulations and exploring the sensitivity to the moist baroclinic life cycle. Our first focus will be on the sensitivity to the stage of the life cycle. Our preliminary findings suggest that at early stages, the intensity and location of the surface cyclone is especially sensitive to synoptic-scale, low-level perturbations that enhance the baroclinic growth. As the cyclone matures, the error growth becomes increasingly influenced by differences in moist convection that project most strongly onto the upper troposphere. Although this upscale growth produces domain-integrated errors that are comparable to those at earlier stages, the changes to the cyclone’s location, intensity, and precipitation are minimal on 2–4-day timescales. Our second focus will be on the sensitivity to the behavior of the baroclinic life cycle. Previous studies have shown that idealized cyclones growing in the presence of strong anticyclonic or cyclonic shear exhibit significantly different behavior. We will consider whether these differences in the baroclinic growth also correspond to differences in the error-growth dynamics.