Atmospheric Influence on Midlatitude Temperature Distributions and Extremes under Global Warming: Insights from an Idealized Model

We use an idealized model of temperature transport by stochastic Rossby waves in midlatitudes to examine non-Gaussian temperature distributions and extremes. This idealized model enables separation of the influences of changes to the background temperature and changes to the flow field, so we can isolate certain processes to determine their effects on the temperature distribution. When we explore changes that are expected with global warming, we find that the decreased equator-to-pole temperature gradient only impacts the variance and no higher order moments, while the shift of the location of the stirring causes substantial changes to the higher order moments as well as the variance. We examine temperature distributions from reanalysis products and explore the seasonal and interannual variability. By modifying our simple idealized model, we explore the mechanisms for this variability. Finally, we quantify the effect of advection on the tendency of different quantiles of the distribution, both with the idealized model and with the reanalysis products. These results suggest that the influence of changes to the large-scale dynamics to the shape of temperature distributions must be considered when predicting the likelihood of future extreme heat and cold.