Exploring atmospheric transport into the Arctic 1940 to 2023 - A Lagrangian Perspective

The Arctic is a key component of the Earth’s climate system and has received much attention in recent years due to it’s above-average warming (Arctic Amplification). Furthermore, we know that the Arctic is not a closed system, but is influenced by atmospheric transport from lower latitudes, a fact that for example can be observed during spring when polluted air transported from lower latitudes regularly leads to a reduction in visibility (Arctic Haze).

In order to better understand the observed warming and pollution events we investigate circulation and transport patterns in the Arctic by calculating residence times, following air particle trajectories to and from the Arctic, and studying the dynamical characteristics of the Polar Dome. For our investigation we employ a newly created Lagrangian Reanalysis (LARA) dataset which is based on global simulations with the Lagrangian Particle Dispersion Model FLEXPART forced with ERA5 reanalysis data for the period 1940 to 2023.

Similar to a previous study we find average Arctic residence times in the order of one (January) to two weeks (July). Preliminary results indicate that these residence times have changed most during the transition months, especially in spring (e.g., shorter Arctic residence times in April at present than in the mid-20^th century). However, we find strong spatial differences in residence times and in their changes over time. In this presentation we aim to discuss the seasonal and spatial characteristic of the residence times, investigate potential pollution source regions, explore the dynamical characteristics of the Polar Dome, and analyze how all of this has changed between 1940 and 2023. Furthermore, we plan to investigate the relation of observed dynamical changes to changes in sea ice, North Atlantic Oscillation, and other observations.