A New Global Lagrangian Analysis of Near-Surface Temperature Extremes

Abstract

Temperature extremes strongly affect the society and the environment, yet a complete physical understanding of their formation mechanisms is still lacking. Specifically, the relative importance of the three key processes—horizontal advection, subsidence accompanied by adiabatic warming, and diabatic heating—remains controversial. This paper presents a global quantification of the contributions from these processes to near-surface temperature extremes using the Lagrangian framework. Two Lagrangian potential temperature anomaly decompositions are applied: one based on the full fields of the respective terms, and the other one based on the anomaly fields of the respective terms (i.e., deviations from their corresponding climatologies). The results from the decomposition based on full fields mostly align with those of a previous study, while the decomposition based on anomaly fields offers a different assessment of the roles of the different processes. Most importantly, horizontal transport is attributed the primary role for both extremes globally.